UPS battery question

[goontron]

i have an older 560watt APC UPS with a shagged battery and a jumpstarter box from Christmas with a cooked board and good battery (14v idle 13.2v under load) so i was wondering, could i take the battery from teh box and connect it to the UPS? the battery is about 4 times the size of the one that came with the UPS.
thanks

[joshnz]

Re: UPS battery question

Are both batterys 12v sla?

[goontron]

Re: UPS battery question

Are both batterys 12v sla?

yes, which is surprising to me because i didn't think an sla could take the sudden amp draw.

[eccerr0r]

Re: UPS battery question

SLA has a very high specific power, depending on the design, they can dump out a LOT of amps (think car battery - in an instant it can send out hundreds of amps for a few seconds.)

The only concern I'd have is the UPS not designed to run for more than a few minutes at the full load provided by the original battery - Talk about cheap design but I'm sure it exists. The manufacturer assumes the battery will run out before the transformer explodes...

[kc8adu]

Re: UPS battery question

yes it will work.
the ups however may have a timer that limits its runtime.
open it up and look at the heatsinks.
if they are solid blocks thats likely what you have.same if case is plastic.
metal case is the good ones.i run those with truck batteries.talk about runtime!

[brethin]

Re: UPS battery question

yes, which is surprising to me because i didn't think an sla could take the sudden amp draw.

SLA not take a sudden amp draw? Please tell me you really didn't think that.

Car batteries are SLA because they can take a sudden amp draw (100's of amps sometimes, just look at the size of the cables used).

The only problem with using a huge SLA battery on a small UPS is that it can cook the UPS during discharge because it is not designed to discharge for longer than the original batteries run time at its rating.

[goontron]

Re: UPS battery question

^
i dont know much about lead-acid batteries, i thought SLA was for long (deep) discharge since i always see them in UPS's........but ask me anything about lithium-ion and i can answer it!
i was planning on adding cooling, but i thought it to be unnecessary. thanks for correcting me.

[mariushm]

Re: UPS battery question

No, in fact SLA batteries will be damaged and lose capacity if you deep discharge them. They're good for sudden bursts of current but for short periods of time.

They're probably used in UPSes due to being very common and easy to replace, standardized..reusing already existing manufacturing base to make stuff cheaper.

There are other batteries lead-crystal batteries, lead-gel batteries etc..

Lead Crystal batteries handle deep discharges very well ... see here video comparing them with regular batteries : https://www.youtube.com/watch?v=O45eLd5YotM#t=86

Lead gel batteries are better at slow discharge but have less capacity than regular batteries... but they need special charging profiles... see info here: http://www.batterystuff.com/kb/artic...el-vs-agm.html

[goontron]

Re: UPS battery question

just looked at both batteries, they are both gel cell. the charging topology is the same, the UPS has a plastic case but has a cooling fan and a chunky (finned) heatsink and is an APC unit.
so this should work(?)

[999999999]

Re: UPS battery question

It may work, or if the UPS is too sophisticated and monitors the amount of time it charges the battery it could think there is a fault from it taking too long to charge a larger battery.

Try it and see. You can shut it off if it gets too hot.

[eccerr0r]

Re: UPS battery question

UPSes use lead acid is because
- lead acid has excellent standby characteristics (low self discharge and fairly easy to maintain charge)
- they are cheap per watt*hour stored
- they have high specific power, at least when in good shape so you don't need huge batteries just to supply many watts.
And the side benefit that since UPSes have no need to be moved, so weight has no bearing.

I don't think UPSes tend to use "gelled" acid, but rather use absorbed glass mat. There's a difference and honestly for most purposes I believe AGM is much better than gelled acid.

[Trick Fix]

Re: UPS battery question

If the UPS is connected to the battery 3 times greater then there is a risk of overheating the charging circuit.
Observe the temperature of the elements to charge the battery because the
charger in the UPS is sized for normal charging current.

Larger batteries require a higher charging current,
and it may be burned in a part of the elements of the UPS.

[gunnish]

Re: UPS battery question

Some UPSes have external battery capability for infinity running time. If that is the case, then no problem, use the battery. If is is one of those plastic cased passively cooled units, then you should probably not run it at max load for longed than the rated time.

[kc8adu]

Re: UPS battery question

the charger is not the limiting factor in anything but recovery time.
for my setups the internal charger is nothing more than a maintainer.
so for fast recovery be prepared to use a suitable charger after a run.
my smallest system has an exide d31 agm semi battery that took 8 hours with a 15a smart charger to recover when i test ran it.

[HKPolice]

Re: UPS battery question

The Jumpstarter box probably came with a starting battery, not deep cycle. If you discharge near zero with the UPS a few times, it will die. If you have no other use for the battery then you can use it, but just remember that it will die after a few blackouts.

[eccerr0r]

Re: UPS battery question

Most absorbed glass mat SLAs can take a bit of deep cycling before they die unlike SLI flooded batteries, due to the plates being fairly tightly packed. What kills SLAs is cooking them as they have no way (or at least it's very difficult) to re-watering if they gas. Also it's somewhat unfortunate you do have to gas them once in a while to equalize the cells. You can still sulfate them to death too of course, but if you keep them charged it shouldn't happen. (Then there's that positive grid cracking problem that all lead acid batteries can succumb to...)

Sometimes it's good if you can get a SLA that you can pop the cap off, so you can pour more water in if needed. I've had limited success in lengthening the life of some SLAs by doing this, but it's no guarantee.

[Elysarian]

Re: UPS battery question

A decent UPS shouldn't deep-cycle it's batteries.

There *should* be monitoring circuitry in there to disconnect the batteries when the terminal voltage drops below a certain point.

I know that cheaper ones will deep-cycle though as I've had to replace them (complete unit - the batteries fried the charging circuit in some cases and in others it is just cheaper in labour cost/parts than swapping the batteries out for new ones).

As for upgrading the batteries to larger ones, I'd be inclined to agree with the caveats posted by others on this thread.