On Mon, 16 Jun 2014 20:18:30 +0100, tony sayer
wrote:

The obvious solution to hours long autonomy by using a petrol genset
is only workable with the more expensive inverter type of genset. An
ordinary 2.8KVA generator will grossly overvolt if it sees even a
modest leading current load. A 4.7uF PF correction cap was enough to
send the nominal 230v north of 270 volts and there's nearly 9uF's
worth in the mains input circuit of the SmartUPS2000 alone, before we
even consider that due to the protected loads themselves - no wonder
the poor UPS kept cycling endlessly between mains and battery power
when it was supplied by the genset!

Yes I've seen just that happening but the generator voltage measured on a true
RMS Fluke meter was indicated at 230 volts;!..


Just out of interest, reproduced below an excerpt of an RAIB report issued today
were a railway level crossing gate system didn't work. Fortunately nothing was
going thru the crossing at the time from the road vehicle direction..

A bit of malarkey with the power it seems and the UPS system. All originally
caused be a RCD tripping which wasn't needed as there were multiple earth's, so
it sez;!....




80. Network Rail issues guidance about UPS systems. The guidance acknowledges
that the batteries of a UPS system ‘are the most critical component’ and are
‘perishable’ in that their performance will degrade over time. The guidance also
states that ‘manufacturers will provide batteries with a design life which will
often not be achieved. For example an 8-10 year battery will probably need
replacing after 7 years provided that maintenance and good temperature control
has been maintained’. The batteries of the UPS system in use at Butterswood
level crossing had not been replaced since the system was installed around 20
years before the incident.


81. The signalling department whose responsibilities included Butterswood level
crossing had no plans to replace the UPS system batteries during the life of the
system. In fact, Network Rails knowledge about the condition of the UPS system
at Butterswood, including the age of its batteries, was incomplete until after
the incident on 25 June 2013.


The data logger


82. The data logger fitted at Butterswood level crossing had its own internal
UPS system, separate from the level crossing’s main UPS system. Normally the
data logger is powered from the main incoming network power supply and uses its
own internal batteries to provide back-up power in the event of a main power
failure for a maximum of 6 hours. The data logger is tested annually by
signalling technicians. The test involves pulling the main network power lead
out of the unit, and checking that the indications are still showing that the
data logger is operating correctly. Network Rail requires that the batteries in
the UPS systems of its data loggers are renewed at no more than 10 yearly
intervals.


For level crossing UPS systems, Network Rail required them to operate for 20% of
their expected performance.

The UPS system at Butterswood level crossing was believed to be capable to
operate for up to 12 hours, therefore the permitted performance time was 2.4
hours.


83. Records indicate that the batteries were replaced in 2012. This means the
batteries only lasted around a year before they failed. Information from the
data logger manufacturer suggested that the batteries may only last 5 years,
depending on how many channels the data logger is monitoring. It was the belief
of the local signalling and electrification and plant teams, that it was often
the case that new batteries can spend significant periods of time ‘on the
shelf’ in store rooms, and could thus be several years old before they are used,
sometimes leading to premature failure.

That's a pretty accurate view regarding backup batteries. However, a
12AH 12v SLA I picked up in my local fleamarket for a fiver about two
years ago has proved to be a rather remarkable example of SLA
technology. It showed 13 point something volts on a borrowed digital
meter at the time of purchase but actually showed only about 12v when
I tested it at home (clearly the borrowed meter's battery was low).

I left it connected to one of those car battery maintainance solar
panels for nearly 6 months to fully charge it up last year, which it
did. It's basically been sat on my office windowsill for nearly a year
without being recharged because every time I checked its voltage, it
was showing 12.78 or so volts, even after using it for brief periods
testing 55W halogen capsule lamps for a minute or two at a time and to
use it as a test supply voltage for other kit every so often.

The total lack of care doesn't appear to have done it any harm and
when I checked it again today, it still showed a healthy 12.76 volts
and still fully lit up a 55W test lamp. I put it on charge from a pair
of those panels mid afternoon today (100mA) and the voltage peaked at
13.25v before settling back to 13.02v after sundown. A test just now
shows a voltage of 12.99v (1:30 am).

Mindful of the comments I'd seen recently about these solar panels
having high reverse leakage sufficient to undo the benefit, I checked
and measured a mere 2 micro-amps (using both a digital meter and an
analogue one on its 30 micro-amp range as a sanity check).

This was for two units in parallel in total darkness (the 33
microvolts open circuit reading probably being due to sodium street
lighting spillover) so whatever others experience might be in this
regard, this is certainly not true for the two units in my possession.

As far as charge retention performance goes, the difference between a
wet cell 12v motorcycle battery bought brand new last year and this
SLA is like night and day. The motorcycle battery (removed from the
T120v) only took a month or three to self discharge from full down to
a mere 6 or 7 volts!

I'm not sure if this is typical of a decent quality of SLA but if it
is, it would seem best _NOT_ to keep them on a float charge long
term. Just a refreshing charge once a year might prove to be the best
bet. Perhaps a float voltage of 13,2v with a brief monthly top up to
13.8v might turn out to be a better solution to achieving longevity in
standby service.

For anyone interested in a 12AH 12v SLA that can be left a whole year
between refreshing charges, the battery is a Chines made 'Maplin'
branded battery also marked as "AINO MICRO" underneath which it has
the following: "AM12-12 (12Volt 12AH)".

I can't spot any obvious date code except possibly one encoded on the
made in China sticker bar code - "5 026686 823035" for the benefit of
anyone who may know how to interpret it. The only other sequence of
digits visible is "0908051" embossed into the top cover plate.
--
J B Good

On Tue, 17 Jun 2014 02:40:19 +0100, Johny B Good wrote:

Mindful of the comments I'd seen recently about these solar panels
having high reverse leakage sufficient to undo the benefit, I checked
and measured a mere 2 micro-amps (using both a digital meter and an
analogue one on its 30 micro-amp range as a sanity check).

Rescued mine from the garage, not a lot inside. Connected across the
PV panel is a blue LED and 5k1 resistor. The ouput has a 1N400? diode
in series, that's the sum total of bits inside. Don't know what the ?
is as that's against the tiny bit of PCB.

The 1N400? range is supposed to have between 5 uA and 50 uA at max
reverse voltage and 25 to 125 C junction temp. Testing gave an open
circuit output voltage of about 19 V. Apply a load and it could
produce about 24 mA @ 12 V ish. Not measured the drak leakage, might
do that later.


I'm not sure if this is typical of a decent quality of SLA but if it
is, it would seem best _NOT_ to keep them on a float charge long
term.

They ought to be OK provided the float is within the spec of the
battery, taking into account the battery temperature. The SLA's in
the alarm panels lasted far longer than those in the UPS. APC UPS's
don't keep within spec of the batteries...

--
Cheers
Dave.

On Tue, 17 Jun 2014 13:06:57 +0100 (BST), "Dave Liquorice"
wrote:

On Tue, 17 Jun 2014 02:40:19 +0100, Johny B Good wrote:

Mindful of the comments I'd seen recently about these solar panels
having high reverse leakage sufficient to undo the benefit, I checked
and measured a mere 2 micro-amps (using both a digital meter and an
analogue one on its 30 micro-amp range as a sanity check).

Rescued mine from the garage, not a lot inside. Connected across the
PV panel is a blue LED and 5k1 resistor. The ouput has a 1N400? diode
in series, that's the sum total of bits inside. Don't know what the ?
is as that's against the tiny bit of PCB.

The diode is most likely a 1N4001, the lowest PIV rating of that
series, one or two hundred volts afair. It's worth keeping in mind
that this represents a volt drop equivilent to slightly more than that
of a single cell but it's a necessary sacrifice not just to prevent
backflow in darkness but also to stop the the LED drawing current from
the load (usually a battery) and giving a false indication. Very
likely the panel will be made up of 30 photocells in series so this
will represent about a 3.3% sacrifice of power output.

The 5K1 resistor rings a bell. I can't remember whether I opened up
the original unit or not but I certainly did for the second one on
account the indicator LED wasn't working (was seeing the same 20ish
open cct volts and able to draw about 80mA charging the battery).

I replaced the self flashing blue LED with an ordinary blue LED but
replaced the 5K1 resistor with, most likely, a 15K one to compensate
for the 100% on duty cycle and also because those blue leds can be
fiendishly bright on anything more than a couple of milliamps, they
use far less current than the older red and green LEDs to achieve the
same brightness.


The 1N400? range is supposed to have between 5 uA and 50 uA at max
reverse voltage and 25 to 125 C junction temp. Testing gave an open
circuit output voltage of about 19 V. Apply a load and it could
produce about 24 mA @ 12 V ish. Not measured the drak leakage, might
do that later.


I'm not sure if this is typical of a decent quality of SLA but if it
is, it would seem best _NOT_ to keep them on a float charge long
term.

They ought to be OK provided the float is within the spec of the
battery, taking into account the battery temperature. The SLA's in
the alarm panels lasted far longer than those in the UPS. APC UPS's
don't keep within spec of the batteries...

Well, the float voltage is so tightly specced that there are three
different voltages quoted for the classic 6 cell battery between the
AGM, Gel and flooded cell types. The optimum voltage being a
compromise to avoid excess corrosion and sulphation for each of the
three cell types although I've never seen anything other than 13.8v
being specified for any of the 12v SLA types (55.2v for a string of 4,
hence my choosing to set the float voltage at 55.3 open circuit but I
think, in the light of the wiki article I should revise this down to
54.1v).

According to wikipedia, the three voltages are 2.23, 2.25 and 2.32
volts per cell. For the 24 cell battery pack I need to select between
a low of 53.52 and a high of 55.68 volts depending on battery type
chosen and, afair, I think VR4 trimpot covers the whole range. The
last time I checked the charging voltage I think it was set to 54.3v
open circuit which may well explain the relatively short lif of the
SLAs (although not for the even shorter life of the car batteries).

Luckily, as well as having a cheapish Aldi DMM to hand, I've also got
a Fluke DMM that _was_ calibrated just before it was gifted to me when
I quit BT just over two decades ago.

When I bought the Aldi DMM, the first thing I did was to compare its
calibration against the Fluke and was assured to see they were within
a couple of millivolts measuring a 12v SLA (as was an even older Tandy
DMM). With three DMMs to hand, I think I can be reasonably confident
of their accuracy being sufficient enough to set the float charge
voltage correctly.
--
J B Good

According to wikipedia, the three voltages are 2.23, 2.25 and 2.32
volts per cell. For the 24 cell battery pack I need to select between
a low of 53.52 and a high of 55.68 volts depending on battery type
chosen and, afair, I think VR4 trimpot covers the whole range. The
last time I checked the charging voltage I think it was set to 54.3v
open circuit which may well explain the relatively short lif of the
SLAs (although not for the even shorter life of the car batteries).


And correct me if I'm wrong this is all temperature sensitive as well?..

--
Tony Sayer

On Wed, 18 Jun 2014 12:18:52 +0100, tony sayer
wrote:


According to wikipedia, the three voltages are 2.23, 2.25 and 2.32
volts per cell. For the 24 cell battery pack I need to select between
a low of 53.52 and a high of 55.68 volts depending on battery type
chosen and, afair, I think VR4 trimpot covers the whole range. The
last time I checked the charging voltage I think it was set to 54.3v
open circuit which may well explain the relatively short lif of the
SLAs (although not for the even shorter life of the car batteries).


And correct me if I'm wrong this is all temperature sensitive as well?..

That is indeed another complication but I have the UPS and batteries
located to the basement which keeps to a fairly narrow temperature
range throughout the year. In any case, I think the charging circuit
includes a couple of thermistors implying that temperature
compensation of some sort is applied.

The wiki article made reference to a tolerance of +/- 0.05v but it's
not clear whether this is a per cell tolerance or a per 12v battery
one. If it's the former, it all rather makes a mockery of the 2.23,
2.25 and 2.32 per cell charging voltage figures.
--
J B Good

On Wed, 18 Jun 2014 12:18:52 +0100, tony sayer wrote:

According to wikipedia, the three voltages are 2.23, 2.25 and 2.32
volts per cell.

And correct me if I'm wrong this is all temperature sensitive as well?..

In the case of SLA's yes and if the duty is "cyclic" or "float".

Yuasa NP7-12L:
Float @ 20C: 2.275 V/cell, derate -3 mV/cell/C
Cyclic @ 20C: 2.420 V/cell, derate -4 mV/Cell/C

I set my APC "smart" UPS based on the figures from the battery makers
datasheet, not wonkypedia. B-) It was set to 27.7 V, the maths and
40 C battery temp for a float charge say 26.58 V. Bring the temp down
to 20 C and the maths still says says 27.3 V. So cooking even without
the temp rise due to the excessive charging.

27.7 V sort of fits with the cyclic figures and battery temps around
40 C but what is the definition of "cyclic"? Daily discharges to
25%? Weekly?
The mains here is pretty good, so there is SFA cycling.

--
Cheers
Dave.

On Wed, 18 Jun 2014 00:38:08 +0100, Johny B Good wrote:

Rescued mine from the garage, not a lot inside. Connected across
the
PV panel is a blue LED and 5k1 resistor. The ouput has a 1N400?
diode
in series, that's the sum total of bits inside. Don't know what
the ?
is as that's against the tiny bit of PCB.

The diode is most likely a 1N4001, the lowest PIV rating of that
series, one or two hundred volts afair.

1N4001 is 50 V. B-) Well I just looked at th spec to get the
leakage.

I replaced the self flashing blue LED with an ordinary blue LED

Mine has an ordinary LED, without a load it stays on. Once there is a
bit of load it starts to flash. I guess this is some interaction
between the panel load and LED. LED off volts rise, LED lights
increase load, volts drop, LED goes out less load, volts rise...

The last time I checked the charging voltage I think it was set to 54.3v
open circuit which may well explain the relatively short lif of the
SLAs (although not for the even shorter life of the car batteries).

Car batteries really don't like any deep discharge and aren't that
keen on constant charging either. So I'm not surprised they died PDQ,
I'm also on the look out for 4 12 V deep discharge batteries for the
2 kVA UPS I have kicking about. Ideally things greater than 100 AHr
but then they'll probably be flooded and vented so not ideal for
being in the equipment cupboard. Back of the garage and run a
"maintained" mains feed in is probably the best option but I've heard
stories that UPS's might object to long output cables.

--
Cheers
Dave.

On 18/06/2014 17:29, Dave Liquorice wrote:
On Wed, 18 Jun 2014 00:38:08 +0100, Johny B Good wrote:

Rescued mine from the garage, not a lot inside. Connected across
the
PV panel is a blue LED and 5k1 resistor. The ouput has a 1N400?
diode
in series, that's the sum total of bits inside. Don't know what
the ?
is as that's against the tiny bit of PCB.

The diode is most likely a 1N4001, the lowest PIV rating of that
series, one or two hundred volts afair.

1N4001 is 50 V. B-) Well I just looked at th spec to get the
leakage.

An 1N5817 would be a better choice - much lower Vf at low currents.

http://www.fairchildsemi.com/ds/1N/1N5818.pdf

They are usually a fair bit better than the datasheet max ratings would
suggest in terms of reverse leakage.

The last time I checked the charging voltage I think it was set to 54.3v
open circuit which may well explain the relatively short lif of the
SLAs (although not for the even shorter life of the car batteries).

Car batteries really don't like any deep discharge and aren't that
keen on constant charging either. So I'm not surprised they died PDQ,
I'm also on the look out for 4 12 V deep discharge batteries for the
2 kVA UPS I have kicking about. Ideally things greater than 100 AHr
but then they'll probably be flooded and vented so not ideal for
being in the equipment cupboard. Back of the garage and run a
"maintained" mains feed in is probably the best option but I've heard
stories that UPS's might object to long output cables.

Old government surplus NiFe are incredibly robust if you can still find
them. They scrapped a fortunes worth of the things in the early 1990's
and then proceeded to destroy a complete batch of new replacement NiCd
by using the same top up 30% recharging regime for a couple of years.

After that they got wise and modified the SOP instructions...

--
Regards,
Martin Brown

On Wed, 18 Jun 2014 17:18:56 +0100 (BST), "Dave Liquorice"
wrote:

On Wed, 18 Jun 2014 12:18:52 +0100, tony sayer wrote:

According to wikipedia, the three voltages are 2.23, 2.25 and 2.32
volts per cell.

And correct me if I'm wrong this is all temperature sensitive as well?..

In the case of SLA's yes and if the duty is "cyclic" or "float".

Yuasa NP7-12L:
Float @ 20C: 2.275 V/cell, derate -3 mV/cell/C
Cyclic @ 20C: 2.420 V/cell, derate -4 mV/Cell/C

I set my APC "smart" UPS based on the figures from the battery makers
datasheet, not wonkypedia. B-) It was set to 27.7 V, the maths and
40 C battery temp for a float charge say 26.58 V. Bring the temp down
to 20 C and the maths still says says 27.3 V. So cooking even without
the temp rise due to the excessive charging.

27.7 V sort of fits with the cyclic figures and battery temps around
40 C but what is the definition of "cyclic"? Daily discharges to
25%? Weekly?
The mains here is pretty good, so there is SFA cycling.

I think the big clue lies with the name of the company from which the
acronymic APC was derived "American Power Conversion Corporation".

It was a company concerned with the outage rates common in many parts
of the US of A so they may well have erred on the side of 'cyclic'
charging voltage requirements rather than for voltages optimised to
continuous float charging very rarely troubled by actual outages.

I think you may well have hit the nail on the head regarding the
float charging voltage settings. Here in the UK, you can go several
years between outages in urban areas where the majority of the
population reside.

The only discharge events the battery is likely to experience will be
due to testing, either scheduled once a fortnight or manually. The
lower continuous float charge voltage setting would seem to be the
better choice for the vast majority of UK users.

According to my min max thermometer, the basement temperature has
been hovering around the 16 deg mark +/- 2 deg this past month or two.
Istr seeing lows of 10 deg last winter so I'm going to reduce the
current 55.3 volt setting down to 54 volts dead when I eventually get
my next set of batteries. I can't see this doing any harm, especially
in view of my experience with that 12AH SLA that's only now being
recharged from the solar panels after a year of 'neglect'.
--
J B Good

On Wed, 18 Jun 2014 17:29:19 +0100 (BST), "Dave Liquorice"
wrote:

On Wed, 18 Jun 2014 00:38:08 +0100, Johny B Good wrote:

Rescued mine from the garage, not a lot inside. Connected across
the
PV panel is a blue LED and 5k1 resistor. The ouput has a 1N400?
diode
in series, that's the sum total of bits inside. Don't know what
the ?
is as that's against the tiny bit of PCB.

The diode is most likely a 1N4001, the lowest PIV rating of that
series, one or two hundred volts afair.

1N4001 is 50 V. B-) Well I just looked at th spec to get the
leakage.

I replaced the self flashing blue LED with an ordinary blue LED

Mine has an ordinary LED, without a load it stays on. Once there is a
bit of load it starts to flash. I guess this is some interaction
between the panel load and LED. LED off volts rise, LED lights
increase load, volts drop, LED goes out less load, volts rise...

If they're the same panel as mine, the leds are self flashing and
shouldn't be effected that way (the working original LED only ever
flashed regardless of the output voltage on no load). Perhaps the self
flashing LED happens to be substandard in regard of its maximum
voltage/drive current it receives when driven by full open circuit
voltage from the panel causing it to misoperate in this way.


The last time I checked the charging voltage I think it was set to 54.3v
open circuit which may well explain the relatively short lif of the
SLAs (although not for the even shorter life of the car batteries).

Car batteries really don't like any deep discharge and aren't that
keen on constant charging either. So I'm not surprised they died PDQ,
I'm also on the look out for 4 12 V deep discharge batteries for the
2 kVA UPS I have kicking about. Ideally things greater than 100 AHr
but then they'll probably be flooded and vented so not ideal for
being in the equipment cupboard. Back of the garage and run a
"maintained" mains feed in is probably the best option but I've heard
stories that UPS's might object to long output cables.

That's pretty close to my own setup (a 2KVA / 1500W SmartUPS2000 in
the basement feeding a 'protected' main supply to several parts of
this 3 floor Victorian semi detached house). I think the longest run
of 2.5mm flat twin and earth exceeds 20 metres (daisychained feed to
my first floor 'office' and then on to the top floor bedroom) and
there doesn't appear to be any problem with those feeds.

I too used to harbour thoughts of using a 100AH battery but in view
of the cost and fairly constant life expectancy regardless of the
chosen battery capacity, I'm looking to a more modest 12 to 25 AH
battery pack for my future investment. That's not to say I wouldn't be
tempted to fit a larger AH pack if the price was right. :-)
--
J B Good

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--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

---
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