Yes, as a general rule of thumb with lead acid batteries, charging
slightly increased if the batteries are cooler.
to the case and extension wires run. Note the following:
http://batteryuniversity.com/learn/article/how_heat_and_harsh_loading_reduces_battery_life
not intended for freezing temps.
(77°F). As a guideline, every 8°C (15°F) rise in temperature will cut
the battery life in half. VRLA, which would last for 10 years at 25°C
(77°F), will only be good for 5 years if operated at 33°C (95°F).
They recommended 2.45v per cell charging and 2.27 topping charge.
Post by Mihalik MátéHello,
One noteworthy addition to all of this (based on self experience), that
smaller sized APC UPS charge voltages should be adjusted in all cases if
you want to get the maximum lifetime out of the batteries. Models like
SU700(I)NET, SUA750(I) have smaller chassis than (for example) SU1400 or
SUA1500, and because of that the components are squeezed into a much
smaller space. In all APC UPSes I have seen so far, the transformer is
the reason for most of the generated heat (not the MOSFETs on the
heatsinks, although they get warm as well). The transformer gets very
hot even though the unit just keeps the batteries on float charge, and
not operating on battery. In SU700 and SUA750, the smaller chassis
eventually gets significantly warm due to the contact with the
transformer's metal parts, which in turn heats up the batteries inside
as well. I am currently using a SUA750I with 14 years old(!!!) CSB 12V
7Ah batteries. I bought the batteries alongside with a larger UPS when
they were already used, and I put them into my SUA750I around a year ago
(they still retain around 90% capacity). Before putting them to use, I
adjusted the float voltage to be around 27.0 volts when the unit is
sitting idle (68F/20C inside room, 91F/32.8C inside the UPS, read from
thermistor - I suspect metal parts are hotter than this). This ensures
that the batteries are not overcharged despite the elevated temperature
inside the chassis, but not undercharged as well.
Trying to muck around with the charging voltage, eh?
It likely doesn't do what you think it does. Leave it alone!!!!
I'm going to post the following about APC UPSes and Lead Acid Gel Cells
(called Valve Regulated Lead Acid, VRLA for short)
A lead-acid battery produces around 2 volts per cell. So, given the
voltage of a "battery" you can divide to calculate the number of cells
in it. For example a 12v 18Ah battery has 12/2 = 6 - six cells in it.
The "traditional" lead acid battery design is lead-antimony. However
lead-antimony, while it's OK for your car battery, it's terrible when
used as a standby battery design where the battery is constantly under
charge. That is why you can't use a car starting battery in a solar
battery array or anything like that - the batteries cannot tolerate
constant charging, under constant charge the antimony migrates to
points on the negative grid.
Traditional charging voltage on lead-antimony is around 2.3 volts per
cell. So for a 12v battery that's 13.8 (2.3 X 6 cells) at room temp.
With VRLA batteries the antimony is replaced with calcium. This was
ALSO done with "maintenance free don't add water" car batteries that
were all the rage about 30 years ago. (General Motors pushed these)
This solves the float charge problem (and the need to replace water) but
it introduces a plethora of other issues.
The first is discharge. Lead-calcium designs do NOT tolerate very high
and deep discharge nor do they tolerate repeated deep discharge.
The second is charging voltage. As it turns out, lead-calcium designs
have to charge at a higher voltage per cell, around 2.33 to 2.35. That
may seem to be very small but it's significant when you have 2
12v batteries wired in series - a lead-antimony charge voltage
would be 27.6 volts, a lead-calcium charge voltage would be at least
a volt higher.
Lastly is individual cell variations. Lead-calcium is NOT an easy alloy
to manufacture, UNLIKE Lead-antimony. Calcium does not easily mix with
molten lead. As a result the individual cells in a battery can have
much greater variations in their lead chemistry in a lead-calcium
battery then a lead-antimony battery. THIS IS INTENSIFIED IN CHEAP
BATTERIES!!! If this happens then during charging the cells internal
resistance will vary and some cells will be overcharged and others
undercharged, which tremendously shortens the battery life.
ALL APC upses manufactured before the SMT series of UPSes use a constant
"float" charger on the batteries. This is a temperature-compensated
charger. What I have seen is that at 75 degrees "room temperature"
when the batteries are discharged, these chargers put out 2.3 X cell
number, while as temperature decreases the charge voltage increases. So
if there's 2 12v batteries that's 12 cells, the charger will run at
around 27.6v, in a 75 degree room (where the internal temp inside the
UPS might be around 120 degrees) while in a 55 degree room with an
internal temp of 100 degrees the charger may increase to 28v Once the
battery charge is at 100% the charger switches down to about 2.25v per
cell (which is a "holding charge" voltage for all lead acid batteries
whether lead-antimony or lead-calcium)
I've looked at many VRLA battery spec sheets and I've seen a number of
incorrect charging voltages listed as floats. For example the Panasonic
https://na.industrial.panasonic.com/sites/default/pidsa/files/panasonic_vrla_up-vw1220p1.pdf
<https://na.industrial.panasonic.com/sites/default/pidsa/files/panasonic_vrla_up-vw1220p1.pdf>
This is actually a very high quality battery - but if you were to float
one of these fully charged at 2.3v per cell you would ruin it within a
year or so. And if you were to charge it at that voltage you would
undercharge it. What is probably happening is that Panasonic is making
a trade-off compromise here - and indeed, the data sheet lists "trickle
charge" not the more scientific "charge" and "float charge" ratings.
A trickle charger is not temperature compensated nor does it switch down
to a float voltage.
So, the moral here is don't trust everything you read in battery specs!
At UPS manufacture, APC specs the extra long life "high current" UPS
batteries from their gel-cel battery vendors. These batteries have
different plate material than simple lead-calcium.
Lead and tin, (tin less than 2%) and calcium (calcium less than 1%)
and sometimes aluminum is added. And there may be further chemistry
changes in the gel than simple sulfuric acid and silica powder.
1) It guarantees the batteries will outlast the warranty.
2) It guarantees the batteries will have long runtimes when the UPS is
on battery
3) It guarantees that the batteries will supply high current during
the time that the UPS is on battery, thus the UPS will supply high
current (lots o PC's)
This leads to some confusion and frustration among users. Let me try
to clarify this.
The small under-5000VA APC upses are ONLY intended as TEMPORARY power.
Meaning, 30 minutes, tops. The exception is the XL series. This is
because APC regards the UPS as only needing to supply power for however
long it takes your generator to spin up and get stable.
I happen to have an old-school 5000VA generator. It really and truly
DOES take about 20 minutes of continuous operation before power from it
is stable enough to switch my servers over to. It has to heat up and
reach operating temp. Of course, I've love to have one of those modern
electronically regulated Honda jobs that can provide stable power in
2 minutes but I'm not made out of money.
If you buy a regular APC UPS with the idea it's going to supply hours of
power during an outage you will be very unhappy. The only UPSes that
APC makes that do that are the XL series and only when you have 1 or
more external battery packs attached to them.
FURTHERMORE APC's sales people have told them "the UPS must be as small
as possible" The customers don't want a large UPS with large 12v 18ah
gel cells or car battery cells with high AH. The fact is that physics
dictate with lead-acid batteries the higher AH requires more space. But
ost customers don't understand physics. There have been in the past
some very good UPSes (like from BEST Power) that have had much
larger batteries coupled with lower power ratings - those did not last
in the market. APC did. End of story.
Anyway, I am trying to make it clear that with the exception of the XL
all the low-end APC UPSes are designed from a wham-bam-thank-you-mame
perspective. Hit 'em with a lot of power and burn down the batteries
while doing it in the smallest space possible.
This requires the highest-capacity highest-discharge lead-acid gel cells
available. Since APC buys batteries by the semi-truck load, they can
squeeze their battery vendors on pricing and for them, these kinds of
batteries are cheap as dirt. These batteries because of their chemistry
and plate design, they require higher charge voltages.
Now we get to the problem - which is along comes the admin, who has a
beeping UPS because the batteries are shot. This is a 4-6 year old
APC UPS with original batteries. The admin takes it apart, takes the
batteries down the street and buys off-the-shelf lead-acid gel cells,
which are much, much, much cheaper than the replacement batteries for
that UPS if bought from APC, plugs them in - and then has a conniption
fit when they get no more than 2 years out of them and then the
batteries have swollen up like balloons and are shot.
The admin then goes out and this time after buying his second set of
replacement batteries, reads their data sheet, uses a volt meter and
decides the APC battery charger is "overcharging" the batteries from
what the battery spec sheet says for his El-Cheapo Chinese lead acid
batteries are supposed to be charged at.
Now, is it overcharging? Maybe, maybe not. If he's just plugged in
a fresh set of batteries that are not fully charged and the UPS has
cooled down from when he pulled the batteries out - then it's charge
voltage is going to be higher - this is normal!
SOP for an APC UPS battery replacement is to plug in the new batteries,
wait a day, then do a calibration, then let them completely recharge for
an hour before doing any sort of testing if you want a decent reading.
It IS my experience that the older beige colored APC UPSes do tend to
overcharge a little bit as they age. I believe this is due to component
drift in the temperature sensor. The temp sensor is a typical
thermistor. ALL THERMISTORS DRIFT AS THEY AGE and this is intensified
the hotter the thermistor is operated at - a thermistor run at 80
degrees is going to drift more as it ages than one operated at 68
degrees. Fortunately, thermistors age with “Thermometric drift”
which means the shift is even across all temps. So if you have to adjust
the UPS charge voltage, it will work for all temps.
Unfortunately, APC's Factory Service Manuals for their UPSes only
include test points and test voltages and such. They do NOT appear to
be expecting that anyone is going to do a board-level repair on their
UPSes. There did appear to be a leak a number of years ago and
schematics ARE out there on the Internet for some of the older APC UPS
models (I have one claiming to be for the smartups 1000-1400 model
for example) but they are only on various sketchy Russian sites right now.
There is only ONE correct way to muck with APC charge voltage - it only
applies to SOME of the UPSes. Someone leaked the internal programming
variables for some of those models and there's some websites and forums
out there that shows how to send commands to the UPS that will reduce
charge voltage. It only works on certain models.
There's also program that was written a few years ago out there -
http://apc-fix.com/apcfix
You can try downloading this (page is in Russian) and running it and
experimenting. This is in monitoring mode only. You can contact the
site owner for the actual program that changes the values.
Note that even if you successfully reduce charge voltage - thereby
allowing you to use your El Cheapo Chinese batteries - you are only
going to get maybe an extra year out of them, tops - and what is worse
is these batteries lose capacity at a much higher rate.
In the United States it's not easy to get the high quality SLA
VRLA batteries. For example with Panasonic they operate through
distributors and there's only a few sites (mouser.com
<http://mouser.com>) that sell
Panasonic batteries online and
on top of that the battery nomenclature is different. For example a
standard 12v 7ah SLA battery from most companies would be part number
127 but Panasonic does not follow that for their high capacity discharge
SLAs they use wattage so the high rate version of that battery would be
http://www.mouser.com/ds/2/315/panasonic_vrla_up-vw1245p1-947508.pdf
<http://www.mouser.com/ds/2/315/panasonic_vrla_up-vw1245p1-947508.pdf>
Amazon for example is flooded with Chinese junk and bait-and-switch
sellers - that same Panasonic part number keyed into an Amazon search
gets you Chinese junk.
But it really does pay
to make the effort - your batteries will last much much longer - without
the need to fuss around with charge voltage - since the higher quality
batteries are manufactured better, have more even plates, less cell
variance, and will produce more power for longer length of time and
are more tolerant of higher float voltages.
Note that any SLA that is sold over the counter to the general public -
like the stuff sold through Batteries Plus in the US, is likely junk -
and the worse thing is that companies like PowerSonic that used to
make decent SLAs have outsourced to China and their quality has gone
down. These days it's really hard to get good data on batteries because
poor quality batteries don't last, while good quality batteries that
are on poor chargers also don't last.
One other thing that seems to be happening in the US is the old
"upsell" as many sellers (like for example Batteries Plus) are now
pushing AGM batteries as SLA replacements. Of course, since AGM is
newer tech - they can get away with demanding more money for it - so
they push the more expensive battery even though there's likely no
difference in this application.
But of course I'm well aware of the lure of using El-Cheapo SLA
batteries that hare highly intolerant, so for those of you who want to
fardle around with your UPSes, I'm appending an edited set of
instructions on how you modify the voltage using Terminal - this is from
http://nissandiesel.dyndns.org/viewtopic.php?t=2891
<http://nissandiesel.dyndns.org/viewtopic.php?t=2891>
Note you can use the TTY mode in apctest to access the UPS instead
of a terminal emulator program.
------------------------------------------------------------------------
List of Smart-UPS models that have been confirmed to be able to have
their float voltage adjusted using these instructions, and the number of
SUA1000 (1)
SUA1000XL (1)
SUA1500 (1)
SU2200 (1)
Units that respond to these instructions, but do not actually adjust the
BP650S (1)
SU700 (1)
SU700NET (1)
SU1400 with firmware 70.9.I (reported by Marc van Dongen, 29Jun2012)
models to this list.
Problem: APC UPSs sometimes have a float charge voltage that is too high
and tends to cook batteries.
Any & all SmartSlot cards must be removed before beginning!
Note that APC has many different firmware revisions for their Smart-UPSs
(as opposed to the firmware in the SmartSlot devices!), and the features
available in Smart Mode vary.
Remove any SmartSlot card from the UPS. This might be a Network
Management Card such as a AP9606, AP9617, AP9618, AP9619, or an
Environmental Monitoring (EM) card.
Use the Serial port. Because the SmartSlot cards must be removed, no
networking is available, so you have to use the serial connection
Connect the Smart-UPS serial cable to the UPS & PC (or terminal
emulator, or, I suppose, a real terminal if you have one ;) ). In my
case, the Smart Signalling 940-0024C (black) DB9xDB9 serial cable. No,
you can't use a straight-through or null-modem cable.
Disable COM-port apps. If using PowerChute, or another UPS Service,
disable it. The terminal program must have exclusive control of the COM
port.
Figure out which port you're using, if there's more than one. I've read
at least one report than a USB<->Serial converter does not work for this
procedure.
Use a terminal program, such as HyperTerminal that's bundled with
versions of Windows. Setup parameters are 8-N-1 (Google what that means,
if you haven't used a terminal program before. HyperTerminal is not a
very good terminal program, but it will suffice.). Flow control is
variously recommended to be "None" or "Xon/Xoff". I was successful with
"None", so I didn't try "Xon/Xoff".
Test the setup. If everything is correct, you should be able to type a
capital 'Y' (that's <Shift+Y>) and the terminal should display "SM": the
UPS is now in Smart Mode. Occasionally, I've had to type 'Y' twice to
get a response.
As a double-check, type a capital 'A'. Otherwise known as <Shift+A>. The
UPS should beep and light up all front-panel LEDs for a couple of
seconds. The terminal may display "OK".
Enter PROG mode by typing "1" followed by "1" again after two seconds.
IF you pulled the SmartSlot card(s) out, and IF you got the timing of
the "1"s right, the terminal will display "PROG". If not, try "Y" + "1"
+ "1" again, using different pauses. The "1" (pause) "1" is the
sensitive part.
If you made it this far, the hard part is over.
Enter "Battery Gain Adjust" mode. Now that the UPS is in PROG mode,
capital "B" (<Shift+B>) will display a voltage (for the SUA1000XL;
apparently, it shows you the Battery Gain Constant. I consider it a
reference only and near-useless. I ignore it and use the voltmeter
exclusively.
B: Battery voltage gain.
0=maximum gain, FF=minimum gain.
Adjust with the batteries fully charged, and an accurate voltmeter
connected.
Factory setting was "E9" on my SUA1500, and "E6" gives me the desired
27.30V battery voltage. . . .
Pressing 'B' (<Shift+B>) will display a voltage. It also puts the unit
in "Battery Gain Adjust" mode (my terminology). It's very easy to have
it drop out of this mode!
In this mode, only the upper row '+' and '-' keys apply. If you press
any other key, it will drop out of Battery Gain Adjust mode. (editors
note: this is dependent on your terminal emulator program)
Pressing '+' will raise the Battery Gain constant one notch, and lower
the float voltage.
Pressing '-' will lower the Battery Gain constant one notch, and raise
the float voltage.
Each keypress changes the float voltage ~0.10v.
Adjust Battery Gain.
With the terminal displaying your supposed battery voltage (Adjust
Battery Gain mode), take note of your voltmeter's reading, then press a
'+' (to lower voltage) or '-' (to raise it). All changes are immediate.
The terminal should now display a two-character Gain Constant, in the
range of 00 to FF, your new Battery Gain Constant. You won't know your
old constant, it never showed it to you (for this model, anyway;
apparently, it does show you the constant for some UPS). To determine
(and record, if you wish) the old constant that you just changed, press
the complementary adjust key ('+' or '-') and your old (previous)
constant value will be displayed. You just moved one step away, then one
step back.
Watch the voltmeter. Wait for the new voltage to stabilize. This can be
anywhere from a few seconds (for my FLAs, <10) to a couple of minutes.
The battery voltage will change about one-tenth of a volt. As long as
you only press '+' or '-', you can adjust up & down forever. The UPS
will remain in Adjust Battery Gain mode.
Chances are, though, that you'll eventually forget to hold down <Shift>
to get the '+' key, and it will display "NO" and drop out of Adjust
Battery Gain mode. To continue adjusting, re-enter the mode by pressing
'B' again. You'll be picking up where you left off.
End the session using 'R' (<Shift+R>). The terminal will show "BYE". You
can close the terminal, disconnect the cable, etc.: you're finished. All
changes are persistent.
Information on float voltage
13.4 V for gelled electrolyte
13.5 V for AGM (absorbed glass mat)
13.9 V for flooded cells
All voltages are at 20 °C (68 °F), and must be adjusted −0.0235V/°C for
temperature changes.
-----------------------------------------------------------------------------
Remember that battery float and charge voltage are different. This post
adjusts float voltage not charge voltage. DO NOT attempt it on a UPS
that does not have fresh batteries and that hasn't gone through a
calibration cycle. I would also NOT attempt a calibration on a kludgy
battery setup (like the wet cell layout the author was using - I love
the pictures of the wet cells sitting on the carpeted floor - he
definitely doesn't have kids!!!)
My experience is that as a rule of thumb, when you replace a battery in
a UPS, if the battery is swollen when you pull it, measure the float
voltage on the new batteries and drop it by .3 volts. This assumes you
are replacing with the same make of battery. Then see if it lasts
longer - and if not, next time, drop it another .3 volts. And so on.
Remember too low a float voltage and they sulphate, too high and they
will bulge and balloon.
Lastly, the SMT series of UPSes reportedly changed their charging
circuit - it now does not power up when the battery is fully charged.
So there is no more of this float nonsense. This is, incidentally, how
the charging circuit works with the 20 year old and older UPSes that
were OEMed to Compaq by Exide. Periodically the UPS will check the
battery and if it has dropped it activates the charger, until the
battery is topped off again. That approach should in theory allow us
to get more life out of the UPS in the future.
Ted
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