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)