# Small UPS Battery String Maintenance



## splatz (May 23, 2015)

You could buy a tester, or I have a place that supplies my batteries for UPSs etc., if I really wanted to keep some of the batteries, I'd have them come out and test them all, haul off the bad ones, and sell me replacements. 

But if there are not maintenance records for the batteries, assume that when one starts smoking, others are not too far behind; I'd replace them all, and put them on a program. 

Are they arranged in groups of four in series?


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## Southeast Power (Jan 18, 2009)

Other time we were on battery string maintenance they were single cells. They can be individually bypassed of course but, taking 12 volts out of a 144 volt string might be too much to lose. 
Also, Im not 100% convinced how many are bad at this point.


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## chicken steve (Mar 22, 2011)

Iirc, they all have a manufacturers lifespan , so if you can find a date you might validate a complete swap out (_assuming they haven't parsed a rotation out_ ) Splatz

~CS~


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## Southeast Power (Jan 18, 2009)

splatz said:


> You could buy a tester, or I have a place that supplies my batteries for UPSs etc., if I really wanted to keep some of the batteries, I'd have them come out and test them all, haul off the bad ones, and sell me replacements.
> 
> But if there are not maintenance records for the batteries, assume that when one starts smoking, others are not too far behind; I'd replace them all, and put them on a program.
> 
> Are they arranged in groups of four in series?


They have an A and B string.
Each of the 4 trays have 12 batteries.
Best I can tell is that They are paralleling the strings in A and B. At this point I suspect that they are possibly paralleling those for 288 volts to feed the inverter. 
As far as replacing all of the batteries. They are selling the building and with that said, each of the batteries are going to cost about $250. 
For them, It would be a 20k project if I were to crap up a couple of days for a couple of guys and come 12k out of pocket for batteries. 
Im starting out changing 4 batteries for 3k and see what happens.
If it turns into a full replacement, so be it.


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## Southeast Power (Jan 18, 2009)

The more I think about it, the more I like swapping them all out.
BTW, the unit has been in service for about 2 years.
That is about it for gel fire alarm batteries.


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## RePhase277 (Feb 5, 2008)

I got the worst shock I've ever had from a bank like that.


If you disconnect the ends of each string, that will electrically isolate each battery for testing with a volt meter or load tester. No need to disconnect each one.


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## splatz (May 23, 2015)

I thought those AGM batteries for golf carts etc. usually had a four year warranty? I am not sure. 

It's possible it wasn't smoking but steaming through its vent but even so I'd think it would be shot. The problem is I am not sure if the usual tests would show reveal that fault, something other than the usual wear. 

I imagine it's worth testing the UPS to make sure everything's functioning properly there and not cooking the batteries, and the one he saw smoking / steaming was just the weakest link. 

I think I'd be calling the battery manufacturer and the UPS manufacturer.


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## RePhase277 (Feb 5, 2008)

UPG only has a 1 year warranty on that model.


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## emtnut (Mar 1, 2015)

Sorry, no shortcuts that I've ever heard of !

If you have some in series, you can measure the voltage of that string. Any in parallel have to be disconnected.

I always measure in a charged state. The volts/cell should be marked on the battery. It will be obvious when you get a weak battery, it will be significantly lower.

On the 8D agm I work on, charged Volts is around 12.7V. 
I usually find one or 2 that are down around 11.5 V or less.

I'd look into the charging voltage too as Splatzy said, overcharging can cause them to smoke too !


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## RePhase277 (Feb 5, 2008)

That particular battery has a float charge voltage of between 13.6 and 13.8 volts, so string charging voltage should be no more than about 165 volts. More than that and they're cooking.

At any rate, if you isolate the ends of each string, each series battery will be invisible to the others, so individual testing will be possible without removing each battery.


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## MechanicalDVR (Dec 29, 2007)

Suncoast Power said:


> The more I think about it, the more I like swapping them all out.
> BTW, the unit has been in service for about 2 years.
> That is about it for gel fire alarm batteries.


Give em a price, $20k against the sale of a building shouldn't be a big deal.


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## splatz (May 23, 2015)

MechanicalDVR said:


> Give em a price, $20k against the sale of a building shouldn't be a big deal.


Especially not compared to what it will cost if the maintenance man doesn't catch it in time.


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## MechanicalDVR (Dec 29, 2007)

splatz said:


> Especially not compared to what it will cost if the maintenance man doesn't catch it in time.


Very much so!


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## Southeast Power (Jan 18, 2009)

It came down to us to do a minimum of changing one complete 24 battery string.
They take a week to get and will cost the customer about 9k for us to change.


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## MechanicalDVR (Dec 29, 2007)

Suncoast Power said:


> It came down to us to do a minimum of changing one complete 24 battery string.
> They take a week to get and will cost the customer about 9k for us to change.


Will you be testing those coming out to save the best as spares for the other string?


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## LARMGUY (Aug 22, 2010)

Be sure to sharpie the date of install on all the new ones.


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## Southeast Power (Jan 18, 2009)

MechanicalDVR said:


> Will you be testing those coming out to save the best as spares for the other string?


Not a bad idea if I find a few a cant walk away from.
I don't want to let them in on onesies and twosies on the other string but, we should grade our pulls and inspect "B" string for any fliers. It would be an amature move to take some useable cells of site as cores if they could solve a small problem.


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## Southeast Power (Jan 18, 2009)

LARMGUY said:


> Be sure to sharpie the date of install on all the new ones.


They do have a record book there but, the whole inside of the fan cooled cabinet housing the inverter and static switch are covered in construction dust.
It would take two hours and a good hepa vac with a few different brushes to clean it up.
Know if that dust gets damp it causes problems.


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## MechanicalDVR (Dec 29, 2007)

Suncoast Power said:


> Not a bad idea if I find a few a cant walk away from.
> I don't want to let them in on onesies and twosies on the other string but, we should grade our pulls and inspect "B" string for any fliers. It would be an amature move to take some useable cells of site as cores if they could solve a small problem.


Exactly my train of thought.

Small thing that could make a great impression with the client that owns other properties.


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## MechanicalDVR (Dec 29, 2007)

Suncoast Power said:


> They do have a record book there but, the whole inside of the fan cooled cabinet housing the inverter and static switch are covered in construction dust.
> It would take two hours and a good hepa vac with a few different brushes to clean it up.
> Know if that dust gets damp it causes problems.


I'd think in Florida the humidity would keep the dust damp.


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