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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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UPS batteries
Hi,
I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? |
#2
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UPS batteries
Hi!
We rarely have outages here. *So, there is no real draw on the batteries in our UPS's. *So, they should just be on float charges. I rarely have power outages here, and my most recent UPS battery change involved a unit that did nothing more than "buffer" a phone system until a generator would come on. Its battery lasted 10 years (1998-2008). The UPS in question is an APC Back-UPS 600. I attribute part of that long lifetime to the fact that the battery could have degraded to where it had almost no runtime left--but that would have been fine as the generator started and stabilized within a few seconds. Can anyone with firsthand knowledge shed some light on this? I can't say that I have firsthand knowledge. (Meaning: I've never designed or built a UPS circuit from scratch...) However, the trouble is likely to come from the float charging. I'm of the impression that at least some UPS units have an awfully "hot" float charge and it probably leads to the battery being overcharged. I've seen some Tripp- Lite UPS units that would slowly drive the water out of their batteries if left float charging all the time. I also think there are some that don't put enough of a float charge on a battery to truly keep it up. I have an older APC Smart-UPS 1000 that demonstrates this behavior--if the power hasn't been out in a while, the battery will drop more quickly than it does when the unit has had only a short time (a few days) between the completion of a battery charge after use and a subsequent power outage. You also have to consider that some UPS designs depend upon their battery and inverter to deal with *every* little power line anomaly. This too will shorten the battery's useful life. This seems to be true of the inexpensive APC "plugstrip" UPS units that many people have. Better designs have methods by which to stabilize, boost or trim the power coming out of them without having to use the battery and inverter. William |
#3
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UPS batteries
D Yuniskis wrote:
Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? Here is where I visit when I have battery questions: http://batteryuniversity.com/ Float voltage is critical for long storage battery life - +/- 0.01V! John :-#)# -- (Please post followups or tech inquiries to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
#4
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UPS batteries
On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis
wrote: Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. That's not what kills most UPS batteries. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). That, but also an unreasonably high float voltage, is what kills them. We've seen literally dozens of UPS' from assorted manufacturers with failed batteries - baked dry, swollen, cracked cases. On fitting new batteries and checking the charger behaviour, we note that the recovery charge rate is definitely "too aggressive" (motive onvious) and the eventual float charge voltage was definitely destined to kill the cells within a year or so. The only time we were happy that the cells were within the manufacturer approved envelope was ... on DISCHARGE. But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? |
#5
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UPS batteries
who where wrote:
On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis wrote: Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. That's not what kills most UPS batteries. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). That, but also an unreasonably high float voltage, is what kills them. We've seen literally dozens of UPS' from assorted manufacturers with failed batteries - baked dry, swollen, cracked cases. On fitting new batteries and checking the charger behaviour, we note that the recovery charge rate is definitely "too aggressive" (motive onvious) and the eventual float charge voltage was definitely destined to kill the cells within a year or so. The only time we were happy that the cells were within the manufacturer approved envelope was ... on DISCHARGE. But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. Once a month, the UPS switches to battery power for a minute, to test the batteries. Given the current drawn, I have to wonder whether the self test function itself tends to limit the life of the batteries. Tests on the rejected batteries suggests that they still have 2/3 of their nominal capacity - but maybe they can't deliver the current required. Sylvia. |
#6
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UPS batteries
Meat Plow wrote:
It was purchased around 2004 and last time I tested it in Oct it ran for an hour unplugged. That's a long time for a UPS, and suggest's it's not heavily loaded. The self test would be similarly undemanding. Sylvia. |
#7
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UPS batteries
On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis
wrote: Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! Define "most". We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. A quality UPS (not one of those cheap Chinese POS units) will regularly exercise the batteries, running discharge/charge cycles and measuring the results. Then the UPS will tell you the condition of the batteries. Yet, the batteries seem to wear out far too frequently, IMO. So you keep a mystery what brand and model UPS you are using... |
#8
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UPS batteries
Meat Plow writes:
On Tue, 08 Dec 2009 23:32:19 +1100, Sylvia Else wrote: Meat Plow wrote: It was purchased around 2004 and last time I tested it in Oct it ran for an hour unplugged. That's a long time for a UPS, and suggest's it's not heavily loaded. The self test would be similarly undemanding. The 350va powers a cable modem, two USB hard drives and a Linksys network storage server 24/7/365. The self test on the two 1000va units simulate a power failure allowing them to run off battery power for 10 seconds or so. Enough time for the unit to evaluate the state of the batteries according to how it was designed. One 1000va unit provides power for a SA Explorer HDTV cable DVR and a Panasonic 51" rear projector TV. The other powers a 3 yr old desktop PC and 22" monitor and a 32" LCD HDTV. I don't think you understand the principals of demand or load well enough. My APC SmartUPS 700 successfully ran selftests up until one of the batteries failed and everything it supplied went down. :-( It runs with a maximum load of 30%. I have been contemplating using two full size 60Ah car batteries externally instead of the small 7Ah internals. |
#9
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UPS batteries
Hi!
I own two APC 1000va units purchased around 2002. Both function perfect and do self tests regularly. Both have 'replace battery' indication if they fail the self test. Don't expect that it will work. If any of my APC UPS units (about 12) are anything to by, the only way you'll know the battery is dead is when it fails to support the load. Most of these are not cheap units, either--they are SmartUPS units that have a true sinewave inverter. So far, only one has ever illuminated the "battery fault" indicator as a result of a self test. Even if they fail to support the load entirely, this is not enough to trip the fault indicator. I've seen plenty of APC units fail prematurely though so I really don't understand the reasons why some do and some don't. The ones I've seen the most failures out of are the ones that were made in China. Every one of them failed in the same way--I came in and found they were dead to the world. No fuses or breakers had blown, and the batteries were good. Out of four units, three have failed in this way. The fourth works but does not really charge its batteries properly. None of my APC units marked as being made in the US or India have failed. Some of them are over ten years old (having had their batteries replaced, of course). And I've owned other brands besides APC but they were not long-lived. I've had good results with APC and Tripp Lite units. Everything else (Belkin, Cyber Power) seems to have a poor lifetime and...interesting...build quality. I have a big stack of CyberPower units and they all look to have failed in the same way--something inside them simply got too hot and gave up the ghost. And every one has had a bad battery. Never seen any Belkin units, but I've heard bad things about them... Buying a UPS that is larger than you need will also improve the lifetime of the unit and its batteries. The ratings provided by the manufacturers are VERY optimistic and only result in a few minutes of operation. William |
#10
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UPS batteries
Don't automatically assume that doubling the batteries will extend the
run time. I was very surprised. I've a 9 year old APC Smart-700 UPS. I tried at one point doubling up on the batteries to extend run time. It performed as expected without the powerchute software running - more than doubling the run time. With powerchute, it performed as if the extra batteries were not there; the run-time calibration 'couldn't see' the extra batteries, perhaps because the EPROM 'knows' that no external batteries were installed. I'd thought the hw/sw would look at the battery voltage (only) and use that value to decide when to shut down; didn't happen. You may get different results - different models, mfrs. firmware, etc. |
#11
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UPS batteries
Hi William,
(and "All" -- I'll try to address all of the posts I have seen here instead of with individual replies) William R. Walsh wrote: I rarely have power outages here, and my most recent UPS battery change involved a unit that did nothing more than "buffer" a phone system until a generator would come on. Its battery lasted 10 years (1998-2008). The UPS in question is an APC Back-UPS 600. IME, when the batteries are toast, you won't get *any* up-time from the UPS. Power goes... and so does the UPS! :-/ I attribute part of that long lifetime to the fact that the battery could have degraded to where it had almost no runtime left--but that would have been fine as the generator started and stabilized within a few seconds. Can anyone with firsthand knowledge shed some light on this? I can't say that I have firsthand knowledge. (Meaning: I've never designed or built a UPS circuit from scratch...) However, the trouble is likely to come from the float charging. I'm of the impression that Agreed. at least some UPS units have an awfully "hot" float charge and it probably leads to the battery being overcharged. I've seen some Tripp- Lite UPS units that would slowly drive the water out of their batteries if left float charging all the time. I've seen lots of UPS's discarded because they have killed their battery packs. Bulging battery cases, cracks, etc. I also think there are some that don't put enough of a float charge on a battery to truly keep it up. I have an older APC Smart-UPS 1000 that demonstrates this behavior--if the power hasn't been out in a while, the battery will drop more quickly than it does when the unit has had only a short time (a few days) between the completion of a battery charge after use and a subsequent power outage. You also have to consider that some UPS designs depend upon their battery and inverter to deal with *every* little power line anomaly. This too will shorten the battery's useful life. This seems to be true of the inexpensive APC "plugstrip" UPS units that many people have. Some UPS's actually power the load continuously and are recharging the battery from the AC line (like telco's operate). I would think this would be more stressful on the switching power supply than the battery (as, essentially, the same current is flowing into the battery as out) Better designs have methods by which to stabilize, boost or trim the power coming out of them without having to use the battery and inverter. I (currently) have: 1x Back-UPS Pro 500 2x Back-UPS ES 550 2x Back-UPS XS 1000 1x Back-UPS RS 1500 1x MX 3000 (all APCC) I discarded a Belkin unit that appeared to be a repackaged Pro 500 (actually had the nice feature of using a removable power cord!) I've also previously discarded a Back UPS 600 (?) as it used a different physical size battery that was hard to come by (since it didn't offer any feature that I didn't have on other UPS's -- and, also had two pigtail power outlets on the rear which always seemed like a kludge). I discarded a large HP "UPS 1000" which was a decent box (I think Astec internals) but totally unsupported. IIRC, it ran off 48V and had another 48V external battery pack. I managed to blow up another larger UPS (3KVA... the size of a dishwasher) by forgetting that power was still available from the battery pack even though the AC mains were disconnected... shorting a 120V battery into damn near anything destroys the "anything"! : ) All of my UPS's are connected to PC's or servers. So, all feed reactive loads. Most are oversized for the loads they power. Occasionally, I will run an extension cord from one of them to power a CF light in another room if we have an outage at night. (a "100 equivalent watt" CF runs for a LONG TIME on a small UPS!) All of the APCC devices have "replace battery" indicators. All of them do a loaded test on power up (for about 2-3 seconds). I am not sure if they periodically run other tests as it is hard to hear the characteristic "buzz" that accompanies the test when a server is running (fan noise). I think all are tied in to their respective computer/server (typically USB or EIA232) though that should just help the machine shut down before power is pulled. I think all of the APCC designs use low voltage primaries. E.g., 12 or 24V. I don't know if the battery abuse is consequential to this (perhaps the charging circuits on the UPS's that I've had that utilized 48V or 120V primaries were better designed of necessity?) I've taken to powering the UPS's off when their loads are not in use. I.e., they can (over?)charge their batteries only while I am using their loads. Thereafter, they act like power strips and let me shut down all of the loads. This is intended to see if the problem I -- and associates -- have been seeing is related to an aggressive float. (it also has the advantage of silencing the silly alarms that signal in the event of a power outage -- if the UPS is on but its loads are NOT, then I really don't want to be bothered by a chorus of half a dozen little "chirpers"!) I don't think it prudent to use regular lead acid batteries ("car batteries") in these applications unless the batteries themselves could be located in a ventilated area -- I'd be wary of outgassing. I had thought of replacing the gelled electrolyte batteries in the UPS that I blew up with car batteries (this would have required *10* such batteries) and locating the UPS in the garage with the batteries on the outside of the building for this very reason. Then, starving the electrolyte in those batteries to improve longevity. In the short term, I see no other remedy for "fixing" the battery mongers... : |
#12
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UPS batteries
Meat Plow wrote:
I don't think you understand the principals of demand or load well enough. blink Where did you get that from? A normal 1000VA unit would not usually have sufficient storage to provide anything approaching 1000VA for an hour. So unless it's a specially high capacity unit, the fact that it can supply its actual load for an hour suggests that that load is nothing like 1000VA. Sylvia. |
#13
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UPS batteries
Thomas Tornblom wrote:
Meat Plow writes: On Tue, 08 Dec 2009 23:32:19 +1100, Sylvia Else wrote: Meat Plow wrote: It was purchased around 2004 and last time I tested it in Oct it ran for an hour unplugged. That's a long time for a UPS, and suggest's it's not heavily loaded. The self test would be similarly undemanding. The 350va powers a cable modem, two USB hard drives and a Linksys network storage server 24/7/365. The self test on the two 1000va units simulate a power failure allowing them to run off battery power for 10 seconds or so. Enough time for the unit to evaluate the state of the batteries according to how it was designed. One 1000va unit provides power for a SA Explorer HDTV cable DVR and a Panasonic 51" rear projector TV. The other powers a 3 yr old desktop PC and 22" monitor and a 32" LCD HDTV. I don't think you understand the principals of demand or load well enough. My APC SmartUPS 700 successfully ran selftests up until one of the batteries failed and everything it supplied went down. :-( That doesn't sound a very sensible design - the expression "next to useless" comes to mind, since it pretty much guarantees the very failure it's designed to protect against. My SOLA UPS certainly didn't do that on any of the times when it decided that the batteries were no longer up to the task. Sylvia. |
#14
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UPS batteries
Thomas Tornblom wrote: Meat Plow writes: On Tue, 08 Dec 2009 23:32:19 +1100, Sylvia Else wrote: Meat Plow wrote: It was purchased around 2004 and last time I tested it in Oct it ran for an hour unplugged. That's a long time for a UPS, and suggest's it's not heavily loaded. The self test would be similarly undemanding. The 350va powers a cable modem, two USB hard drives and a Linksys network storage server 24/7/365. The self test on the two 1000va units simulate a power failure allowing them to run off battery power for 10 seconds or so. Enough time for the unit to evaluate the state of the batteries according to how it was designed. One 1000va unit provides power for a SA Explorer HDTV cable DVR and a Panasonic 51" rear projector TV. The other powers a 3 yr old desktop PC and 22" monitor and a 32" LCD HDTV. I don't think you understand the principals of demand or load well enough. My APC SmartUPS 700 successfully ran selftests up until one of the batteries failed and everything it supplied went down. :-( It runs with a maximum load of 30%. I have been contemplating using two full size 60Ah car batteries externally instead of the small 7Ah internals. Make sure you keep a couple fire extinguishers handy. -- Offworld checks no longer accepted! |
#15
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UPS batteries
On Tue, 08 Dec 2009 13:14:30 +1100, Sylvia Else
wrote: who where wrote: On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis wrote: Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. That's not what kills most UPS batteries. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). That, but also an unreasonably high float voltage, is what kills them. We've seen literally dozens of UPS' from assorted manufacturers with failed batteries - baked dry, swollen, cracked cases. On fitting new batteries and checking the charger behaviour, we note that the recovery charge rate is definitely "too aggressive" (motive onvious) and the eventual float charge voltage was definitely destined to kill the cells within a year or so. The only time we were happy that the cells were within the manufacturer approved envelope was ... on DISCHARGE. But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? Once a month, the UPS switches to battery power for a minute, to test the batteries. Given the current drawn, I have to wonder whether the self test function itself tends to limit the life of the batteries. The battery current to provide full UPS output is generally pushing the envelope. But vecause it is typically for ten minutes or less, it is generally not that deleterious IMOE. Tests on the rejected batteries suggests that they still have 2/3 of their nominal capacity - but maybe they can't deliver the current required. Capacity, yes. But internal resistance will be too high to allow any decent discharge current.. |
#16
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UPS batteries
who where wrote:
On Tue, 08 Dec 2009 13:14:30 +1100, Sylvia Else wrote: who where wrote: On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis wrote: Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. That's not what kills most UPS batteries. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). That, but also an unreasonably high float voltage, is what kills them. We've seen literally dozens of UPS' from assorted manufacturers with failed batteries - baked dry, swollen, cracked cases. On fitting new batteries and checking the charger behaviour, we note that the recovery charge rate is definitely "too aggressive" (motive onvious) and the eventual float charge voltage was definitely destined to kill the cells within a year or so. The only time we were happy that the cells were within the manufacturer approved envelope was ... on DISCHARGE. But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? I haven't checked that. My AVO meter apparently has a significant voltage drop on its current range which messes up the result Sylvia. |
#17
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UPS batteries
Michael A. Terrell wrote:
Thomas Tornblom wrote: Meat Plow writes: On Tue, 08 Dec 2009 23:32:19 +1100, Sylvia Else wrote: Meat Plow wrote: It was purchased around 2004 and last time I tested it in Oct it ran for an hour unplugged. That's a long time for a UPS, and suggest's it's not heavily loaded. The self test would be similarly undemanding. The 350va powers a cable modem, two USB hard drives and a Linksys network storage server 24/7/365. The self test on the two 1000va units simulate a power failure allowing them to run off battery power for 10 seconds or so. Enough time for the unit to evaluate the state of the batteries according to how it was designed. One 1000va unit provides power for a SA Explorer HDTV cable DVR and a Panasonic 51" rear projector TV. The other powers a 3 yr old desktop PC and 22" monitor and a 32" LCD HDTV. I don't think you understand the principals of demand or load well enough. My APC SmartUPS 700 successfully ran selftests up until one of the batteries failed and everything it supplied went down. :-( It runs with a maximum load of 30%. I have been contemplating using two full size 60Ah car batteries externally instead of the small 7Ah internals. Make sure you keep a couple fire extinguishers handy. Such a modified UPS would clearly run for much longer, but given the run time of a typical UPS on its standard batteries, I'd have thought any heat sinks would be approaching thermal equilibrium, and wouldn't get much hotter on an extended run. Charging? Sylvia. |
#18
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UPS batteries
D Yuniskis wrote:
Sylvia Else wrote: Michael A. Terrell wrote: Thomas Tornblom wrote: [attributions elided] I have been contemplating using two full size 60Ah car batteries externally instead of the small 7Ah internals. Make sure you keep a couple fire extinguishers handy. Such a modified UPS would clearly run for much longer, but given the run time of a typical UPS on its standard batteries, I'd have thought any heat sinks would be approaching thermal equilibrium, and wouldn't get much hotter on an extended run. Charging? I think the point was that lead acid car batteries produce H2. Quite easy to ignite *in* a house : He could always put them outside. Sylvia. |
#19
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UPS batteries
Sylvia Else wrote:
Michael A. Terrell wrote: Thomas Tornblom wrote: [attributions elided] I have been contemplating using two full size 60Ah car batteries externally instead of the small 7Ah internals. Make sure you keep a couple fire extinguishers handy. Such a modified UPS would clearly run for much longer, but given the run time of a typical UPS on its standard batteries, I'd have thought any heat sinks would be approaching thermal equilibrium, and wouldn't get much hotter on an extended run. Charging? I think the point was that lead acid car batteries produce H2. Quite easy to ignite *in* a house : |
#20
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UPS batteries
Sylvia Else wrote:
D Yuniskis wrote: Sylvia Else wrote: Michael A. Terrell wrote: Thomas Tornblom wrote: [attributions elided] I have been contemplating using two full size 60Ah car batteries externally instead of the small 7Ah internals. Make sure you keep a couple fire extinguishers handy. Such a modified UPS would clearly run for much longer, but given the run time of a typical UPS on its standard batteries, I'd have thought any heat sinks would be approaching thermal equilibrium, and wouldn't get much hotter on an extended run. Charging? I think the point was that lead acid car batteries produce H2. Quite easy to ignite *in* a house : He could always put them outside. Yes, this was the approach I was taking. But, for most smaller UPS's you need 5 - 10X the desired output current from the battery pack. So, the farther the batteries are located from the actual UPS, the heavier the wire needs to be in order to keep IR losses manageable. And, the batteries are then subjected to the weather (temperature extremes, etc) |
#21
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UPS batteries
A quality UPS (not one of those cheap Chinese POS units)
will regularly exercise the batteries, running discharge/charge cycles and measuring the results. Then the UPS will tell you the condition of the batteries. Compared to other types of cells, lead-acid cells are relatively "fragile". (I once destroyed a $45 Sony battery pack by accidentally letting it run down.) The /last/ thing you want to be doing with a lead-acid battery is charging and discharging it to determine its capacity. And what, pray tell, is going to happen if the AC goes out when the battery is at the bottom end of the discharge-charge cycle? This is not unlike punching a hole in life boat to test how quickly it will sink! |
#22
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UPS batteries
Buying a UPS that is larger than you need will also improve
the lifetime of the unit and its batteries. The ratings provided by the manufacturers are VERY optimistic and only result in a few minutes of operation. Remember to set the computer so that it'll shut down after a few minutes of battery operation, should you not be around to turn it off manually. |
#23
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UPS batteries
Some UPSs actually power the load continuously and are
recharging the battery from the AC line (like telco's operate). Actually, /all/ UPSs work that way. The common type of unit -- which costs less -- is properly called a Standby Power Supply (SPS). The circuitry doesn't come on until power is lost. |
#24
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UPS batteries
William Sommerwerck wrote:
A quality UPS (not one of those cheap Chinese POS units) will regularly exercise the batteries, running discharge/charge cycles and measuring the results. Then the UPS will tell you the condition of the batteries. Compared to other types of cells, lead-acid cells are relatively "fragile". (I once destroyed a $45 Sony battery pack by accidentally letting it run down.) The /last/ thing you want to be doing with a lead-acid battery is charging and discharging it to determine its capacity. And what, pray tell, is going to happen if the AC goes out when the battery is at the bottom end of the discharge-charge cycle? This is not unlike punching a hole in life boat to test how quickly it will sink! They're not running them down much. Just enough to determine the batterys' health. Even this must certainly cause some aging, but it's better than having batteries with no significant capacity on the day that it's needed. Sylvia. |
#25
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UPS batteries
William Sommerwerck wrote:
Some UPSs actually power the load continuously and are recharging the battery from the AC line (like telco's operate). Actually, /all/ UPSs work that way. The common type of unit -- which costs less -- is properly called a Standby Power Supply (SPS). The circuitry doesn't come on until power is lost. Sorry, I wasn't clear: "THE INVERTERS IN some UPS's actually power the load continuously and are recharging the battery from the AC line (like telco's operate)." This is typically called an "online" UPS. Net current flowing into/out of the battery is zero once charged. But, current flowing into the *inverter* is directly proportional to the load current being supplied EVEN WHEN AC POWER IS AVAILABLE. I.e., these have zero transfer times. This is how the telco CO's operate (in the US, at least) -- everything runs off battery though those batteries are continuously being charged (replenished) Cheaper UPS's, by comparison, are "offline" UPS's -- the battery is charged from the mains "as needed" but the inverter only supplies power to the load when AC power has failed. Typically, a switch disconnects the load from the AC mains and connects it to the inverter's output in this situation. As such, there is a nonzero transfer time as the switch flips from one "position" to the other. (note that this switch is not present in the online UPS!) Online UPS's provide isolation of the load from the mains. As such, fluctuations in the mains (phase and or magnitude) are insignificant (except to the extent that they hinder charging of the battery). OTOH, the electronics are continually stressed in these UPS's *and* the user sees an apparent increase in power consumption as the inverter's (in)efficiency is *always* reflected in the power drawn from the mains. Loads serviced by offline UPS's are exposed to the mains until the UPS decides otherwise. Since the UPS can only detect problems with the mains after the fact, the only remedy that the UPS has to a detected problem is to switch the load to the inverter's output to bridge the "problem". As such, it is impractical to handle cycle-at-a-time problems on the mains. In these scenarios, "line interactive" UPS's can be a win as they allow the UPS's output to be adjusted *without* the use of the inverter -- typically, by dynamically switching the taps being used on an autotransformer in series between the mains and the load (i.e., this only applies to operation on the mains). For small-ish loads, these usually aren't worth the added cost/weight (as most electronic devices can usually adapt themselves to a wide range of mains voltages). |
#26
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UPS batteries
D Yuniskis writes:
Sylvia Else wrote: D Yuniskis wrote: Sylvia Else wrote: Michael A. Terrell wrote: Thomas Tornblom wrote: [attributions elided] I have been contemplating using two full size 60Ah car batteries externally instead of the small 7Ah internals. Make sure you keep a couple fire extinguishers handy. Such a modified UPS would clearly run for much longer, but given the run time of a typical UPS on its standard batteries, I'd have thought any heat sinks would be approaching thermal equilibrium, and wouldn't get much hotter on an extended run. Charging? I think the point was that lead acid car batteries produce H2. Quite easy to ignite *in* a house : He could always put them outside. Yes, this was the approach I was taking. But, for most smaller UPS's you need 5 - 10X the desired output current from the battery pack. So, the farther the batteries are located from the actual UPS, the heavier the wire needs to be in order to keep IR losses manageable. And, the batteries are then subjected to the weather (temperature extremes, etc) Many batteries are available with venting hoses that can be used to vent the gasses outside. Required in cars like my old audi, where the battery is installed under the rear seat, in good VW tradition ;-) I noticed that the SmartUPS can be SW configured with a number of external battery packs. I configured the UPS to believe it had one and two external battery packs, and by interpolating the run time it showed with the various number of external batteries it appears that they are nominally 20Ah. So a couple of 60Ah batteries would be equivalent to three external battery packs, and would power my stuff for over 5 hours. |
#27
Posted to sci.electronics.repair
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UPS batteries
Thomas Tornblom wrote:
D Yuniskis writes: Sylvia Else wrote: D Yuniskis wrote: Sylvia Else wrote: Michael A. Terrell wrote: Thomas Tornblom wrote: [attributions elided] I have been contemplating using two full size 60Ah car batteries externally instead of the small 7Ah internals. Make sure you keep a couple fire extinguishers handy. Such a modified UPS would clearly run for much longer, but given the run time of a typical UPS on its standard batteries, I'd have thought any heat sinks would be approaching thermal equilibrium, and wouldn't get much hotter on an extended run. Charging? I think the point was that lead acid car batteries produce H2. Quite easy to ignite *in* a house : He could always put them outside. Yes, this was the approach I was taking. But, for most smaller UPS's you need 5 - 10X the desired output current from the battery pack. So, the farther the batteries are located from the actual UPS, the heavier the wire needs to be in order to keep IR losses manageable. And, the batteries are then subjected to the weather (temperature extremes, etc) Many batteries are available with venting hoses that can be used to vent the gasses outside. Required in cars like my old audi, where the battery is installed under the rear seat, in good VW tradition ;-) I noticed that the SmartUPS can be SW configured with a number of external battery packs. I configured the UPS to believe it had one and two external battery packs, and by interpolating the run time it showed with the various number of external batteries it appears that they are nominally 20Ah. So a couple of 60Ah batteries would be equivalent to three external battery packs, and would power my stuff for over 5 hours. Though it hardly sounds worthwhile unless you experience frequent extended outages, or have mission critical systems running. Sylvia. |
#28
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UPS batteries
Sylvia Else wrote:
who where wrote: On Tue, 08 Dec 2009 13:14:30 +1100, Sylvia Else wrote: who where wrote: On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis wrote: Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. That's not what kills most UPS batteries. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). That, but also an unreasonably high float voltage, is what kills them. We've seen literally dozens of UPS' from assorted manufacturers with failed batteries - baked dry, swollen, cracked cases. On fitting new batteries and checking the charger behaviour, we note that the recovery charge rate is definitely "too aggressive" (motive onvious) and the eventual float charge voltage was definitely destined to kill the cells within a year or so. The only time we were happy that the cells were within the manufacturer approved envelope was ... on DISCHARGE. But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? I haven't checked that. My AVO meter apparently has a significant voltage drop on its current range which messes up the result Sylvia. I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. Sylvia. |
#29
Posted to sci.electronics.repair
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UPS batteries
Sylvia Else wrote:
who where wrote: On Tue, 08 Dec 2009 13:14:30 +1100, Sylvia Else wrote: who where wrote: On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis wrote: Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. That's not what kills most UPS batteries. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). That, but also an unreasonably high float voltage, is what kills them. We've seen literally dozens of UPS' from assorted manufacturers with failed batteries - baked dry, swollen, cracked cases. On fitting new batteries and checking the charger behaviour, we note that the recovery charge rate is definitely "too aggressive" (motive onvious) and the eventual float charge voltage was definitely destined to kill the cells within a year or so. The only time we were happy that the cells were within the manufacturer approved envelope was ... on DISCHARGE. But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? I haven't checked that. My AVO meter apparently has a significant voltage drop on its current range which messes up the result Sylvia. I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. Sylvia. |
#30
Posted to sci.electronics.repair
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UPS batteries
Sylvia Else wrote:
Sylvia Else wrote: who where wrote: On Tue, 08 Dec 2009 13:14:30 +1100, Sylvia Else wrote: who where wrote: On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis wrote: Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. That's not what kills most UPS batteries. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). That, but also an unreasonably high float voltage, is what kills them. We've seen literally dozens of UPS' from assorted manufacturers with failed batteries - baked dry, swollen, cracked cases. On fitting new batteries and checking the charger behaviour, we note that the recovery charge rate is definitely "too aggressive" (motive onvious) and the eventual float charge voltage was definitely destined to kill the cells within a year or so. The only time we were happy that the cells were within the manufacturer approved envelope was ... on DISCHARGE. But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? I haven't checked that. My AVO meter apparently has a significant voltage drop on its current range which messes up the result Sylvia. I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. Sylvia. I've measured the temperature in the battery compartment, and it's showing about 10 degrees celsius above ambient. Sylvia. |
#31
Posted to sci.electronics.repair
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UPS batteries
Sylvia Else wrote:
Sylvia Else wrote: who where wrote: On Tue, 08 Dec 2009 13:14:30 +1100, Sylvia Else wrote: who where wrote: On Mon, 07 Dec 2009 14:09:42 -0700, D Yuniskis wrote: Hi, I don't have anything other than "gut feel" to resort to as evidence but it sure *seems* like most UPS designs EAT batteries! We rarely have outages here. So, there is no real draw on the batteries in our UPS's. So, they should just be on float charges. Yet, the batteries seem to wear out far too frequently, IMO. I could possibly understand regular outages cycling the batteries too deeply. That's not what kills most UPS batteries. And, chargers too aggressively replenishing them (after all, a UPS that quits because its battery wasn't fully recharged earns a bad reputation for its manufacturer). That, but also an unreasonably high float voltage, is what kills them. We've seen literally dozens of UPS' from assorted manufacturers with failed batteries - baked dry, swollen, cracked cases. On fitting new batteries and checking the charger behaviour, we note that the recovery charge rate is definitely "too aggressive" (motive onvious) and the eventual float charge voltage was definitely destined to kill the cells within a year or so. The only time we were happy that the cells were within the manufacturer approved envelope was ... on DISCHARGE. But, I can't see how even periodic battery tests (performed by the UPS itself) could be the problem -- unless there is something wrong with the approach being used? Can anyone with firsthand knowledge shed some light on this? I.e., what *is* the UPS doing to/with the battery when it is not being used to supply the load? Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? I haven't checked that. My AVO meter apparently has a significant voltage drop on its current range which messes up the result Sylvia. I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. Sylvia. I've measured the temperature in the battery compartment, and it's showing about 10 degrees celsius above ambient. Sylvia. |
#32
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UPS batteries
Hi!
IME, when the batteries are toast, you won't get *any* up-time from the UPS. *Power goes... and so does the UPS! *:-/ I guess I consider them toast when the UPS still holds the load, it just holds it for a few seconds or minutes--or it visibly struggles to keep things going. (Meaning the output voltage sags to the point where equipment won't work. Most don't do that, but some do.) I've seen lots of UPS's discarded because they have killed their battery packs. *Bulging battery cases, cracks, etc. Most of the ones I see aren't that catastrophic. Perhaps that comes from not realizing that they have failed and leaving them plugged in for ages, presumably trying to charge batteries that simply cannot do any more. Apart from a few Tripp-Lite units, the worst I've seen is one or more cells that simply ran out of liquid. Very few units that I come into contact with use gel-cell batteries. In fact, the only one that I ever saw one that did was a really big old Tripp-Lite monster that went "bang!" every time it powered on and that put off an even bigger BANG and smoke when something inside blew up. Some UPS's actually power the load continuously and are recharging the battery from the AC line (like telco's operate). I would think this would be more stressful on the switching power supply than the battery (as, essentially, the same current is flowing into the battery as out) I suppose it is, and that means the inverter itself must be built well enough to stand a high load and constant operation. I've also previously discarded a Back UPS 600 (?) as it used a different physical size battery that was hard to come by (since it didn't offer any feature that I didn't have on other UPS's -- and, also had two pigtail power outlets on the rear which always seemed like a kludge). I have some similar units that got lawn tractor batteries as replacements. By all indications they work fine. I managed to blow up another larger UPS (3KVA... the size of a dishwasher) by forgetting that power was still available from the battery pack even though the AC mains were disconnected... shorting a 120V battery into damn near anything destroys the "anything"! *: ) HeHeHe...and it probably puts off a nice bang, some ozone and "a bit" of a spot weld on the shorting object--when and if it ever comes back down to earth. The biggest UPS that I've had personally was an ancient APC 1200VA unit. It seemed to be pretty well protected with massive sand fuses between the batteries and inverter, and large circuit breakers on the output side. I once hooked it up to some car batteries (the biggest ones I had sitting around) and abused it a little bit by hooking up a moderately sized 110 volt room air conditioner. It struggled to start the A/C but once it was running, everything was fine. I just had to try it. More than once the UPS just gave up and quietly shut down. It still worked when I sent it off for recycling. I just didn't need it and had nowhere to put the batteries. It hummed almost like a microwave whenever it kicked on and had an impressive inverter inside it. All of my UPS's are connected to PC's or servers. *So, all feed reactive loads. *Most are oversized for the loads they power. Occasionally, I will run an extension cord from one of them to power a CF light in another room if we have an outage at night. (a "100 equivalent watt" CF runs for a LONG TIME on a small UPS!) I ought to get that going again. I rigged up a very nice power outage lighting system for my basement with an old APC UPS and a BIG gel cell battery. (The battery got snaked from work after the Tripp Lite UPS blew up. It was basically new and fit nothing else they had, so it was either that or they would have trashed both of them.) I should have used CFL bulbs at the time and didn't. I also never added a relay to make the lights go on when power went off--they had to be manually operated or on all the time. All of the APCC devices have "replace battery" indicators. All of them do a loaded test on power up (for about 2-3 seconds). It's not a very good test and won't spot a faulty battery unless it is REALLY bad. The particular 1200VA UPS I mentioned above would pass its self test on the completely exhausted internal batteries every time. Yet if you pulled the plug, it went down, not across. I think all of the APCC designs use low voltage primaries. *E.g., 12 or 24V. *I don't know if the battery abuse is consequential to this (perhaps the charging circuits on the UPS's that I've had that utilized 48V or 120V primaries were better designed of necessity?) That's what I've seen on the smaller models that come in capacities up to 1500VA--which covers pretty much all the Back UPS series. These also have modified sine wave inverters. The bigger ones (Smart UPS 750XL and bigger) all seem to use 48 volt battery arrangements (four twelve volt batteries) and most have true sine wave inverters. They also have forced air cooling. I've taken to powering the UPS's off when their loads are not in use. That really could only happen on a UPS where the load is supported by the inverter all the time. If there is good line power on a traditional line-interactive UPS (a relay closes and energizes the inverter when the lights go out) it won't use the battery for anything. Most designs also charge the battery whenever they are plugged in. A few (most notably the cheap APC "plugstrip" UPS units will *drain* their battery even when turned "off" and unplugged. I guess this is because the power switch is "soft" and doesn't shut the microcontroller down. (it also has the advantage of silencing the silly alarms that signal in the event of a power outage -- if the UPS is on but its loads are NOT, then I really don't want to be bothered by a chorus of half a dozen little "chirpers"!) Heh. I usually remove the beepers from the units I buy when I get them. I don't want to hear them for any reason, and telling the bundled control software to turn the speaker off usually won't make it quiet all the time (it would still come on if the battery were nearly depleted or bad) and you've got to install it. So I just yank 'em with a quick touch from the desoldering iron. I don't think it prudent to use regular lead acid batteries ("car batteries") in these applications unless the batteries themselves could be located in a ventilated area -- I'd be wary of outgassing. I've done it and never had a problem. Any room that's decently trafficked or serviced by an air handler (or furnace) should move enough air to dissipate whatever gas might show up. I've also never noticed the characteristic smell of the gas building up near the batteries when they were in use. However, I did take some precautions with the ones that I have here. Most notably, they are in a breathable container with a lid and openings that would be unlikely to spew nasty stuff even if the battery went off. To my knowledge, all lead acid batteries are vented somehow, so even the ones that came in your UPS will release some gas if they have to. William |
#33
Posted to sci.electronics.repair
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UPS batteries
Hi!
IME, when the batteries are toast, you won't get *any* up-time from the UPS. *Power goes... and so does the UPS! *:-/ I guess I consider them toast when the UPS still holds the load, it just holds it for a few seconds or minutes--or it visibly struggles to keep things going. (Meaning the output voltage sags to the point where equipment won't work. Most don't do that, but some do.) I've seen lots of UPS's discarded because they have killed their battery packs. *Bulging battery cases, cracks, etc. Most of the ones I see aren't that catastrophic. Perhaps that comes from not realizing that they have failed and leaving them plugged in for ages, presumably trying to charge batteries that simply cannot do any more. Apart from a few Tripp-Lite units, the worst I've seen is one or more cells that simply ran out of liquid. Very few units that I come into contact with use gel-cell batteries. In fact, the only one that I ever saw one that did was a really big old Tripp-Lite monster that went "bang!" every time it powered on and that put off an even bigger BANG and smoke when something inside blew up. Some UPS's actually power the load continuously and are recharging the battery from the AC line (like telco's operate). I would think this would be more stressful on the switching power supply than the battery (as, essentially, the same current is flowing into the battery as out) I suppose it is, and that means the inverter itself must be built well enough to stand a high load and constant operation. I've also previously discarded a Back UPS 600 (?) as it used a different physical size battery that was hard to come by (since it didn't offer any feature that I didn't have on other UPS's -- and, also had two pigtail power outlets on the rear which always seemed like a kludge). I have some similar units that got lawn tractor batteries as replacements. By all indications they work fine. I managed to blow up another larger UPS (3KVA... the size of a dishwasher) by forgetting that power was still available from the battery pack even though the AC mains were disconnected... shorting a 120V battery into damn near anything destroys the "anything"! *: ) HeHeHe...and it probably puts off a nice bang, some ozone and "a bit" of a spot weld on the shorting object--when and if it ever comes back down to earth. The biggest UPS that I've had personally was an ancient APC 1200VA unit. It seemed to be pretty well protected with massive sand fuses between the batteries and inverter, and large circuit breakers on the output side. I once hooked it up to some car batteries (the biggest ones I had sitting around) and abused it a little bit by hooking up a moderately sized 110 volt room air conditioner. It struggled to start the A/C but once it was running, everything was fine. I just had to try it. More than once the UPS just gave up and quietly shut down. It still worked when I sent it off for recycling. I just didn't need it and had nowhere to put the batteries. It hummed almost like a microwave whenever it kicked on and had an impressive inverter inside it. All of my UPS's are connected to PC's or servers. *So, all feed reactive loads. *Most are oversized for the loads they power. Occasionally, I will run an extension cord from one of them to power a CF light in another room if we have an outage at night. (a "100 equivalent watt" CF runs for a LONG TIME on a small UPS!) I ought to get that going again. I rigged up a very nice power outage lighting system for my basement with an old APC UPS and a BIG gel cell battery. (The battery got snaked from work after the Tripp Lite UPS blew up. It was basically new and fit nothing else they had, so it was either that or they would have trashed both of them.) I should have used CFL bulbs at the time and didn't. I also never added a relay to make the lights go on when power went off--they had to be manually operated or on all the time. All of the APCC devices have "replace battery" indicators. All of them do a loaded test on power up (for about 2-3 seconds). It's not a very good test and won't spot a faulty battery unless it is REALLY bad. The particular 1200VA UPS I mentioned above would pass its self test on the completely exhausted internal batteries every time. Yet if you pulled the plug, it went down, not across. I think all of the APCC designs use low voltage primaries. *E.g., 12 or 24V. *I don't know if the battery abuse is consequential to this (perhaps the charging circuits on the UPS's that I've had that utilized 48V or 120V primaries were better designed of necessity?) That's what I've seen on the smaller models that come in capacities up to 1500VA--which covers pretty much all the Back UPS series. These also have modified sine wave inverters. The bigger ones (Smart UPS 750XL and bigger) all seem to use 48 volt battery arrangements (four twelve volt batteries) and most have true sine wave inverters. They also have forced air cooling. I've taken to powering the UPS's off when their loads are not in use. That really could only happen on a UPS where the load is supported by the inverter all the time. If there is good line power on a traditional line-interactive UPS (a relay closes and energizes the inverter when the lights go out) it won't use the battery for anything. Most designs also charge the battery whenever they are plugged in. A few (most notably the cheap APC "plugstrip" UPS units will *drain* their battery even when turned "off" and unplugged. I guess this is because the power switch is "soft" and doesn't shut the microcontroller down. (it also has the advantage of silencing the silly alarms that signal in the event of a power outage -- if the UPS is on but its loads are NOT, then I really don't want to be bothered by a chorus of half a dozen little "chirpers"!) Heh. I usually remove the beepers from the units I buy when I get them. I don't want to hear them for any reason, and telling the bundled control software to turn the speaker off usually won't make it quiet all the time (it would still come on if the battery were nearly depleted or bad) and you've got to install it. So I just yank 'em with a quick touch from the desoldering iron. I don't think it prudent to use regular lead acid batteries ("car batteries") in these applications unless the batteries themselves could be located in a ventilated area -- I'd be wary of outgassing. I've done it and never had a problem. Any room that's decently trafficked or serviced by an air handler (or furnace) should move enough air to dissipate whatever gas might show up. I've also never noticed the characteristic smell of the gas building up near the batteries when they were in use. However, I did take some precautions with the ones that I have here. Most notably, they are in a breathable container with a lid and openings that would be unlikely to spew nasty stuff even if the battery went off. To my knowledge, all lead acid batteries are vented somehow, so even the ones that came in your UPS will release some gas if they have to. William |
#34
Posted to sci.electronics.repair
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UPS batteries
Sylvia Else wrote:
Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? I haven't checked that. My AVO meter apparently has a significant voltage drop on its current range which messes up the result I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. I had argued that UPS manufacturers would err in favor of faster charge times just to reduce the user's perceived "exposure" *after* an outage. I.e., the available up-time from the UPS shortly after an outage is obviously MUCH less than the up-time available at the start of that immediately previous outage (because the battery now has less reserves). If a second outage followed the first before the battery was able to recover substantial capacity, the user would be disappointed in how "crappy" the UPS's performance was Sure, the user would expect the UPS to be unable to maintain the load for the full duration *shortly* after an outage... but, how long does the user's acceptance of this reduced capacity extend *after* such an outage? Surely, the next *day* the user would expect the UPS to behave AS IF there had never been a previous outage! But, how would they feel about it 12 hours after the first outage? 6 hours? etc. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. grin I don't have much "sympathy" for you there! That's sort of like complaining that you only had *two* dates for the high school PROM... :-/ I think I've been lucky to get *perhaps* two years out of batteries. Of course, that's reflecting the batteries that I have discarded because the UPS "told me" they were bad (idiot light) *plus* those that I was able to LEARN were bad based on empirical evidence: they didn't hold up the load when there *was* an outage! I will be curious to see how life expectancy is affected by NOT leaving the UPS's running unless their loads were also "on"... |
#35
Posted to sci.electronics.repair
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UPS batteries
Sylvia Else wrote:
Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? I haven't checked that. My AVO meter apparently has a significant voltage drop on its current range which messes up the result I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. I had argued that UPS manufacturers would err in favor of faster charge times just to reduce the user's perceived "exposure" *after* an outage. I.e., the available up-time from the UPS shortly after an outage is obviously MUCH less than the up-time available at the start of that immediately previous outage (because the battery now has less reserves). If a second outage followed the first before the battery was able to recover substantial capacity, the user would be disappointed in how "crappy" the UPS's performance was Sure, the user would expect the UPS to be unable to maintain the load for the full duration *shortly* after an outage... but, how long does the user's acceptance of this reduced capacity extend *after* such an outage? Surely, the next *day* the user would expect the UPS to behave AS IF there had never been a previous outage! But, how would they feel about it 12 hours after the first outage? 6 hours? etc. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. grin I don't have much "sympathy" for you there! That's sort of like complaining that you only had *two* dates for the high school PROM... :-/ I think I've been lucky to get *perhaps* two years out of batteries. Of course, that's reflecting the batteries that I have discarded because the UPS "told me" they were bad (idiot light) *plus* those that I was able to LEARN were bad based on empirical evidence: they didn't hold up the load when there *was* an outage! I will be curious to see how life expectancy is affected by NOT leaving the UPS's running unless their loads were also "on"... |
#36
Posted to sci.electronics.repair
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UPS batteries
D Yuniskis wrote:
Sylvia Else wrote: Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? I haven't checked that. My AVO meter apparently has a significant voltage drop on its current range which messes up the result I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. I had argued that UPS manufacturers would err in favor of faster charge times just to reduce the user's perceived "exposure" *after* an outage. I.e., the available up-time from the UPS shortly after an outage is obviously MUCH less than the up-time available at the start of that immediately previous outage (because the battery now has less reserves). If a second outage followed the first before the battery was able to recover substantial capacity, the user would be disappointed in how "crappy" the UPS's performance was Unless outages are that frequent, I wouldn't have thought that enough users would experience this problem often enough for it to impact on the manufacturer's reputation, particularly as anyone hearing the complaint would tend to express the "what did you expect" response. The extra cost of the components required to obviate this to some extent would weight heavily on the manufacturer's mind. Sure, the user would expect the UPS to be unable to maintain the load for the full duration *shortly* after an outage... but, how long does the user's acceptance of this reduced capacity extend *after* such an outage? Surely, the next *day* the user would expect the UPS to behave AS IF there had never been a previous outage! But, how would they feel about it 12 hours after the first outage? 6 hours? etc. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. grin I don't have much "sympathy" for you there! That's sort of like complaining that you only had *two* dates for the high school PROM... :-/ I think I've been lucky to get *perhaps* two years out of batteries. Of course, that's reflecting the batteries that I have discarded because the UPS "told me" they were bad (idiot light) *plus* those that I was able to LEARN were bad based on empirical evidence: they didn't hold up the load when there *was* an outage! My "three" years is based on throwing them out when the UPS says they're no good. As I've indicated, they're far from being dead at that point. I should note that I don't usually run them down far during outages. My philosophy is that if the power isn't back within a couple of minutes, it's probably something that'll take longer to fix than the UPS can handle, and the UPS is directed to turn off. This gives me time to save work, etc, if I'm actually doing something at the time. I don't think there's been an outage where the UPS got turned off, but the power returned within the time that the UPS could have run. I will be curious to see how life expectancy is affected by NOT leaving the UPS's running unless their loads were also "on"... It's far from clear that that's a good idea. Instead of a float charge, you're exposing the batteries to self-discharge for a period, followed by a higher chargin current for a while. Sylvia. |
#37
Posted to sci.electronics.repair
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UPS batteries
D Yuniskis wrote:
Sylvia Else wrote: Both my old and my new SOLA UPS use a float voltage of 13.5 volts (near enough), which is at the low end of the battery manufacturer's recommendation (13.5 to 13.8). I get about three years out of batteries in the old UPS. Too soon to say about the new one. That takes care of one of the killer parameters - float voltage. But at what rate do they recharge after a serious discharge? I haven't checked that. My AVO meter apparently has a significant voltage drop on its current range which messes up the result I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. I had argued that UPS manufacturers would err in favor of faster charge times just to reduce the user's perceived "exposure" *after* an outage. I.e., the available up-time from the UPS shortly after an outage is obviously MUCH less than the up-time available at the start of that immediately previous outage (because the battery now has less reserves). If a second outage followed the first before the battery was able to recover substantial capacity, the user would be disappointed in how "crappy" the UPS's performance was Unless outages are that frequent, I wouldn't have thought that enough users would experience this problem often enough for it to impact on the manufacturer's reputation, particularly as anyone hearing the complaint would tend to express the "what did you expect" response. The extra cost of the components required to obviate this to some extent would weight heavily on the manufacturer's mind. Sure, the user would expect the UPS to be unable to maintain the load for the full duration *shortly* after an outage... but, how long does the user's acceptance of this reduced capacity extend *after* such an outage? Surely, the next *day* the user would expect the UPS to behave AS IF there had never been a previous outage! But, how would they feel about it 12 hours after the first outage? 6 hours? etc. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. grin I don't have much "sympathy" for you there! That's sort of like complaining that you only had *two* dates for the high school PROM... :-/ I think I've been lucky to get *perhaps* two years out of batteries. Of course, that's reflecting the batteries that I have discarded because the UPS "told me" they were bad (idiot light) *plus* those that I was able to LEARN were bad based on empirical evidence: they didn't hold up the load when there *was* an outage! My "three" years is based on throwing them out when the UPS says they're no good. As I've indicated, they're far from being dead at that point. I should note that I don't usually run them down far during outages. My philosophy is that if the power isn't back within a couple of minutes, it's probably something that'll take longer to fix than the UPS can handle, and the UPS is directed to turn off. This gives me time to save work, etc, if I'm actually doing something at the time. I don't think there's been an outage where the UPS got turned off, but the power returned within the time that the UPS could have run. I will be curious to see how life expectancy is affected by NOT leaving the UPS's running unless their loads were also "on"... It's far from clear that that's a good idea. Instead of a float charge, you're exposing the batteries to self-discharge for a period, followed by a higher chargin current for a while. Sylvia. |
#38
Posted to sci.electronics.repair
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UPS batteries
Sylvia Else wrote:
D Yuniskis wrote: Sylvia Else wrote: I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. I had argued that UPS manufacturers would err in favor of faster charge times just to reduce the user's perceived "exposure" *after* an outage. I.e., the available up-time from the UPS shortly after an outage is obviously MUCH less than the up-time available at the start of that immediately previous outage (because the battery now has less reserves). If a second outage followed the first before the battery was able to recover substantial capacity, the user would be disappointed in how "crappy" the UPS's performance was Unless outages are that frequent, I wouldn't have thought that enough users would experience this problem often enough for it to impact on the manufacturer's reputation, particularly as anyone hearing the complaint would tend to express the "what did you expect" response. Dunno. As cynical as I am, I still find it hard to believe the manufacturers are intentionally trying to cook batteries. It's just not the sort of market where users will put up with high maintenance costs -- I suspect most users discard the UPS when the "battery breaks" and *probably* don't even bother replacing the UPS (if they wouldn't bother with replacing the battery, they probably wouldn't bother replacing the entire UPS!). Its sort of like "tape (or other) backup systems". Its the sort of thing people *think* they should have -- until it becomes too much of a nuisance. Then, they just learn to live *without* it. So, by comparison, it wouldn't make sense for tape backup manufacturers to design their equipment to *prematurely* wear out the media. Its *not* like toilet paper -- where you *have* to buy more when yours runs out! : The extra cost of the components required to obviate this to some extent would weight heavily on the manufacturer's mind. Of course. And as they try to creep lower into the market (to braoden their markets from the traditional "large businesses" which originally saw needs for these things), it only gets worse. But, I think it costs nothing to float the battery at the *proper* voltage. And, nothing to change the charging algorithms ("its just software") to be more gentle on the batteries. I would *guess* that a UPS battery that lasted "a long time" would be met with pleasant regard -- "Gee, that last one lasted me 5 years... I guess I could pony up for another one to get *another* five years!" E.g., you get a car battery (in these parts) to last five years and you are *literally* "tickled". Six years has you downright giddy! Sure, the user would expect the UPS to be unable to maintain the load for the full duration *shortly* after an outage... but, how long does the user's acceptance of this reduced capacity extend *after* such an outage? Surely, the next *day* the user would expect the UPS to behave AS IF there had never been a previous outage! But, how would they feel about it 12 hours after the first outage? 6 hours? etc. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. grin I don't have much "sympathy" for you there! That's sort of like complaining that you only had *two* dates for the high school PROM... :-/ I think I've been lucky to get *perhaps* two years out of batteries. Of course, that's reflecting the batteries that I have discarded because the UPS "told me" they were bad (idiot light) *plus* those that I was able to LEARN were bad based on empirical evidence: they didn't hold up the load when there *was* an outage! My "three" years is based on throwing them out when the UPS says they're no good. As I've indicated, they're far from being dead at that point. I should note that I don't usually run them down far during outages. My philosophy is that if the power isn't back within a couple of minutes, it's probably something that'll take longer to fix than the UPS can handle, and the UPS is directed to turn off. This gives me time to save work, etc, if I'm actually doing something at the time. I have found them most useful in handling things like "switching transients" and other momentary outages ("Hey, did the lights just blink in here?") that are *just* long enough to cause a PC (or some piece of peripheral kit) to reset. I wouldn't think of running under UPS operation -- it would be just too damn stressful ("I wonder how much longer the power will be out? I wonder how much longer the UPS will last? I wonder how much longer this 3D render will take???") OTOH, if you are in the middle of typing a line of code and power fails, its usually *really* hard to remember what you were working on at that instant! And, no way to recover exactly that. I don't think there's been an outage where the UPS got turned off, but the power returned within the time that the UPS could have run. I will be curious to see how life expectancy is affected by NOT leaving the UPS's running unless their loads were also "on"... It's far from clear that that's a good idea. Instead of a float charge, you're exposing the batteries to self-discharge for a period, followed by a higher chargin current for a while. These are PC's. They see use every day. The battery sits for 12 hours "self discharging" then gets floated for the next 12 hours. I suspect the effect can't be any worse than floating it "too hot" for the 24 continuous hours. shrug As I said, I will see how this affects battery life. If I find myself tossing out batteries just as often, then I'm no worse for the wear (and, I will have saved the energy being dissipated in the UPS while the *loads* were switched off) |
#39
Posted to sci.electronics.repair
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UPS batteries
Sylvia Else wrote:
D Yuniskis wrote: Sylvia Else wrote: I obtained an ammeter. On both UPSs the initial charge current is less than one amp. The battery manufacturer's recommended maximum charge current is more than two amps. This is not that surprising. Providing a large charging current would involve more expensive components, and provide limited real benefit. I had argued that UPS manufacturers would err in favor of faster charge times just to reduce the user's perceived "exposure" *after* an outage. I.e., the available up-time from the UPS shortly after an outage is obviously MUCH less than the up-time available at the start of that immediately previous outage (because the battery now has less reserves). If a second outage followed the first before the battery was able to recover substantial capacity, the user would be disappointed in how "crappy" the UPS's performance was Unless outages are that frequent, I wouldn't have thought that enough users would experience this problem often enough for it to impact on the manufacturer's reputation, particularly as anyone hearing the complaint would tend to express the "what did you expect" response. Dunno. As cynical as I am, I still find it hard to believe the manufacturers are intentionally trying to cook batteries. It's just not the sort of market where users will put up with high maintenance costs -- I suspect most users discard the UPS when the "battery breaks" and *probably* don't even bother replacing the UPS (if they wouldn't bother with replacing the battery, they probably wouldn't bother replacing the entire UPS!). Its sort of like "tape (or other) backup systems". Its the sort of thing people *think* they should have -- until it becomes too much of a nuisance. Then, they just learn to live *without* it. So, by comparison, it wouldn't make sense for tape backup manufacturers to design their equipment to *prematurely* wear out the media. Its *not* like toilet paper -- where you *have* to buy more when yours runs out! : The extra cost of the components required to obviate this to some extent would weight heavily on the manufacturer's mind. Of course. And as they try to creep lower into the market (to braoden their markets from the traditional "large businesses" which originally saw needs for these things), it only gets worse. But, I think it costs nothing to float the battery at the *proper* voltage. And, nothing to change the charging algorithms ("its just software") to be more gentle on the batteries. I would *guess* that a UPS battery that lasted "a long time" would be met with pleasant regard -- "Gee, that last one lasted me 5 years... I guess I could pony up for another one to get *another* five years!" E.g., you get a car battery (in these parts) to last five years and you are *literally* "tickled". Six years has you downright giddy! Sure, the user would expect the UPS to be unable to maintain the load for the full duration *shortly* after an outage... but, how long does the user's acceptance of this reduced capacity extend *after* such an outage? Surely, the next *day* the user would expect the UPS to behave AS IF there had never been a previous outage! But, how would they feel about it 12 hours after the first outage? 6 hours? etc. So the net result is that neither of my UPSs is using an excessive float charge voltage, nor an excessive charge current, but I still only see three years life out of the batteries. grin I don't have much "sympathy" for you there! That's sort of like complaining that you only had *two* dates for the high school PROM... :-/ I think I've been lucky to get *perhaps* two years out of batteries. Of course, that's reflecting the batteries that I have discarded because the UPS "told me" they were bad (idiot light) *plus* those that I was able to LEARN were bad based on empirical evidence: they didn't hold up the load when there *was* an outage! My "three" years is based on throwing them out when the UPS says they're no good. As I've indicated, they're far from being dead at that point. I should note that I don't usually run them down far during outages. My philosophy is that if the power isn't back within a couple of minutes, it's probably something that'll take longer to fix than the UPS can handle, and the UPS is directed to turn off. This gives me time to save work, etc, if I'm actually doing something at the time. I have found them most useful in handling things like "switching transients" and other momentary outages ("Hey, did the lights just blink in here?") that are *just* long enough to cause a PC (or some piece of peripheral kit) to reset. I wouldn't think of running under UPS operation -- it would be just too damn stressful ("I wonder how much longer the power will be out? I wonder how much longer the UPS will last? I wonder how much longer this 3D render will take???") OTOH, if you are in the middle of typing a line of code and power fails, its usually *really* hard to remember what you were working on at that instant! And, no way to recover exactly that. I don't think there's been an outage where the UPS got turned off, but the power returned within the time that the UPS could have run. I will be curious to see how life expectancy is affected by NOT leaving the UPS's running unless their loads were also "on"... It's far from clear that that's a good idea. Instead of a float charge, you're exposing the batteries to self-discharge for a period, followed by a higher chargin current for a while. These are PC's. They see use every day. The battery sits for 12 hours "self discharging" then gets floated for the next 12 hours. I suspect the effect can't be any worse than floating it "too hot" for the 24 continuous hours. shrug As I said, I will see how this affects battery life. If I find myself tossing out batteries just as often, then I'm no worse for the wear (and, I will have saved the energy being dissipated in the UPS while the *loads* were switched off) |
#40
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UPS batteries
D Yuniskis wrote:
Dunno. As cynical as I am, I still find it hard to believe the manufacturers are intentionally trying to cook batteries. Particularly if their users do as I do, and just buy an equivalent SLA from their local electronics shop, rather than going back to the manufacture of the UPS. I've noticed that my new UPS, which I originally though has a custom pack actually has a battery pack which is just two standard 7.2Ah SLA's separated by some foam plastic, and stuck together with tape. Maybe they hope that that way they'll make more sales of replacement batteries. Not from me, they won't. Sylvia. |
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