Rejuvenating SLAs

I've a dozen group 24 AGM batteries pulled from one of my UPSs as "approaching end of life" (easier to pull them while they aren't complaining than to wait until they sh*t the bed at some inappropriate time!)

I'm debating idling that UPS, for a while. So, the logical thing to do is just recycle the old batteries and bank the "core charges" for the day when I need to replace them in the future.

*But*, I can also tinker with them to see if there's any practical way of extending their useful life! [lots of youtube videos and the like but I suspect many of those folks are *just* tinkering and not really expecting any savings from their efforts (no one ever follows up to indicate how long the battery's service was extended nor how its capacity was affected)]

Of course, that means finding a place to store them (or, reinstall in UPS) instead of enjoying a bit less clutter! :-/

So, anyone with first-hand experience on these larger units?

Reply to
Don Y
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I just tried to Equalize a GP12120 AGM that is 5 years old. No dice for this one. Some say 5-8 hrs will pull off the sulfation but I had no luck, only 1/2 capacity left. On the other Hand I have another CSB 7AH battery that has not been used in 4 years and it still has the rated capacity.

For the group 24, check witht he mfg, some say yes to equalization and some say no.

Cheers

Reply to
Martin Riddle

Once upon a time,i used to get battery rejects from weelchairs and the like - both sealed (mostly AGM types) and liquid (unsealed),some suitable for a truck. First cleaned them up, and then applied a quick 100 A test for one second to weed out not-too-profitable-to-recover-by-recycling-charge methods. Then put the "good' ones on standard charger; let them sit for a day and then full 10 second 100 A test 10V or better to pass.

Those that passed this went back to wait a day for second 100 A full test.

Never tried to check battery's service life before/after nor the capacity. However, the larger ones seemed to be good enough to start a truck, and all those that passed were good enough to be put back online in medical mobility units that they had come from (scooters, etc).

Oh, to tweak some of you, i stored all of them on my cement garage floor.

Thanks,

Reply to
Robert Baer

or.

I worked at Sears one Christmas season in the garage. We would charge batt eries, slowly, for a day or two and then test them. The guy teaching me em phasized strongly to sit the battery on a piece of wood instead of the conc rete. I have no idea how that is supposed to make any difference other tha n possibly temperature. Let a liquid container sit on a concrete floor and it most likely will be a couple or few degrees colder than if it is not on the floor directly.

Has anyone ever heard a rational for this idea?

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  Rick C. 

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Reply to
Ricketty C

My experience of SLAs in UPSs is that they are toast once they begin to swell and nothing you can do will make them recover. Also you probably don't want to put them back into a unit since they can swell up enough to deform the metal frame and make removal very difficult before the UPS fails them on self test. So far I have never encountered one that had swelled enough to burst but some were very reluctant to come out.

If you are using them for powering a cattle fence outdoors then you can abuse them how you like with little consequence but if you are putting them into a UPS that you rely on I would err on the side of caution.

Not sure how big group 24 AGM is...

--
Regards, 
Martin Brown
Reply to
Martin Brown

Not an issue if the battery has been manufactured in the past several decades! :>

OTOH, if stored in an unheated space and not "floated", you run the risk of a freeze causing the case to crack and leak on your cement floor.

Reply to
Don Y

I see a lot of discarded ("recycled") UPSs. It's fairly common to see cases ruptured and plates exposed. No doubt a consequence of poor maintenance/servicing.

My interest was more out of curiosity. I.e., *can* I (reliably) get additional life from them with some modest amount of effort (they are ~$200/ea). Even if that meant exposing the inter-cell connections to recondition the cells individually.

Roughly the size of the starting battery used in a 6-8 cylinder vehicle (e.g., they're 48 pounds, each)

Reply to
Don Y

...

I heard "The temperature difference room air vs floor causes the electolyte to form layers"

--
  Jasen.
Reply to
Jasen Betts

Yes, any swelling or bulge is an indication that they should be discarded via sales as scrap lead.

Think i mentioned i worked on truck batteries, much larger.

Reply to
Robert Baer

That could not happen with an AGM.

Reply to
Robert Baer

Thought you meant Sealed Lead Acid. AGM is a lead acid battery that is sealed but SLA is also a flooded/liquid lead acid battery without the glass mat.

AGMs plump when you cook them. i.e. they get fat when it gets hot.

My expereice with plump AGMs that have gotten hot as a result of inbalance between batteries is that they aren't much good anymore.

The way to balance pretty much any lead acid battery bank is to charge each one individually at the proper absorb voltage for the manufacturer's recommended amount of time... Usually a couple hours or maybe more. After they batteries are at the same voltage then you can try putting them back into a series string again (if they were in a string) and try again. If the one AGM starts to act up, get new batteries. If they were in parallel, then it's easier since they are by definition at the same voltage.

Reply to
boB

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