Battery Geniuses...What would you do?

[Artsyguy]

Just scored a nice Merry Christmas to me gift!  My office building was getting rid of 4 SLA deep cycle 12v, 33ah Batteries that were used in my building's security system for backup.  My facilities guy gave them to me!  The labels on the batteries indicate that 3 of them tested as "passed" in 6/2016, the other battery which is a different make had a "failed" sticker on it.  I took all 4 thinking that if all else fails, I would at least be able to save a core charge when I purchase a battery when installing my house system in my van this spring.  I was originally thinking of buying a new, Vented Lead deep cycle, 12v, approx 100-120ah to use.  Won't be using solar.  Just charging off my van battery with solenoid and a smart charger when I can plug into shore power.  I will be running LED interior lighting off these and a FantasticFan, and charging phone and iPad.  That's it.  No heavy uses planned.

So now that you know the background, what would you do regarding testing, charging, and using these unknown batteries?  Should I forget battery #4 or try to incorporate that into my pack?  I would wire these in parallel so my output would be 12V.  I'm assuming, under ideal conditions I should be getting around 120-130ah use with these wired like this?  When I take them home tonite I'll put a multi volt meter to see where they are at and then will mostly likely need to buy some type of battery charger to re-charge.  Any advice on what I should buy to do that? Cheapo from Harbor Freight?  Any step by step to test and see if I have something I can actually use would be appreciated.  I've attached a pic so you can see what I got.

Thanks!
Mark

 

[Trebor English]

What I did was use the volt meter first.  Then I used my old dumb charger on the lowest voltage battery first.  After 8 hours I moved the charger to the next better battery.  Repeat.  Then I let them all sit for 5 days and recheck the voltage.  The ones that held a charge got load tested with an old car headlight bulb.  Then the good ones got wired together and charged some more.  To be useful they need to take a charge, hold it several days then give it back.  I got 2 good ones out of 6.  They lasted 6 months.

 

[tx2sturgis]

Assuming the batteries are charged, or you can make a good attempt to charge them (as per above), then the next morning, buy a dozen Krispy Kreme (or similar) donuts and take the donuts and all the batteries to an auto shop, AutoZone, NAPA, salvage yard, somewhere with a battery load tester. Not just a voltmeter, it actually puts a load on the batteries. 

Offer the donuts to the guys if they will hook up the clamps and test the batteries. 

Have them test all the batteries right in front of you, and see how they do.

Donuts in the morning are as good as a tip at most auto repair shops....

And if they decline the donuts...enjoy!

(Note: some here might recommend that you buy a battery load tester, but if you only need to test 4 batteries, I wouldn't)

 

[Artsyguy]

Just put the multimeter on the batteries. 3 of them measured at 12.4V The 4th one was 4.7V. So it looks like at worst, I'll have 3 working batteries to start with...I'll do a drain on them and then recharge and see how that goes before I incorporate them into my build. Thanks again for the suggestions.

 

[Weight]

So some place below 99 ah. Old batteries have less ah than when new. They will let you test your set up and determine if you need more than 100ah. Then core charge for a pair of 6 volt golf cart batteries.

 

[John TF]

Just put the multimeter on the batteries.  3 of them measured at 12.4V  The 4th one was 4.7V.  So it looks like at worst, I'll have 3 working batteries to start with...I'll do a drain on them and then recharge and see how that goes before I incorporate them into my build.  Thanks again for the suggestions.

Do not " I'll do a drain " , most any lead acid battery will be damaged by a total drain , the older the battery , the worse the damage .
Proper battery testing involve several steps , using the correct charging for any battery's spec. it is called the C rating - that is the correct voltage & current that also includes a specific time , sealed battery's take lower current because of being sealed .
Go to the manufactures site and get the spec.s for those batteries .
Then you can find the correct charger for getting the longest life from the batteries .
With the proper charger fully charge the battery , then a load test - this is also done with the correct spec.s for any battery , you do not want to pull 100's of amp from these types of batteries , they were not meant for engine starting .
I did not notice any labeling indicating deep cycle , so for load testing " draining " you may not want to take more than about 20% capacity out of battery for testing .
All kinda general for how to test batteries .
More specific to your post , forget the 4th battery , and with only lighting - low current draw , the condition of batteries will not matter much , but again if not deep-cycle , using only 20% of capacity will give longer life .
Also , recharging any lead base battery , recharging right after any use - helps to keep sulfating to a min. - again longer life .
Using mis-match batteries [ make , model & age ] will make for shorter life , so I would not add a battery to what you have .
When getting free batteries , you gain cheap lessons - if you kill them , it doesn't cost anything , but learning what you can do with them , before buying new , then the knowledge gained will help to make your next battery system last longer .
My last battery bank [ 4 Trojan L16's ] in my solar system , with 2500 watt inverter charger , running Airstream trailer , including air-conditioner , I got over 12 yrs. from that battery bank , living full time RVing .

 

[tx2sturgis]

With the proper charger fully charge the battery , then a load test - this is also done with the correct spec.s for any battery , you do not want to pull 100's of amp from these types of batteries , they were not meant for engine starting .

Yep, in my previous post, I was assuming that the load test would be done properly, but if someone tries to load test one at 100 amps then that won't be good. 

Most professional load testers can be set for the size battery being tested.

 

[Trebor English]

In post #2 I suggested a load test with an old headlight bulb.  I have one with a burned out low beam.  The high beam takes about 5.5 amps.  A bad battery will be done in 5 minutes, maybe .5 minutes.  If the 33 amp hour battery keeps the light on for 10 or 15 minutes over 11 volts and then bounces back over 12 when disconnected it is worth more recharging.  Otherwise it's not worth the electricity to do any more charging.  The idea is to sort out the batteries that aren't worth messing with.

In my experience new batteries are cheap enough so that old ones aren't worth buying testing equipment or spending much time on them.  I don't like good stuff being trashed and keeping with "Cheap RV Living" they are worth some effort.  A proper load test or a 20 hour capacity test isn't worth the bother.  Are you only going to accept it if it has 80% of the rated capacity?  If that's the case, recycle without even charging to perform the first test.  If you want to extract the last bit of use out of batteries that got replaced based on a schedule and aren't dead yet then there is some value there.  Use them for lights or an electric shaver.  Don't depend on them for an emergency personal locator beacon or a portable AED defibrillator.

 

[John61CT]

Assuming the 33AH rating was for the standard 20-hour rate, a 1.5A load will be close enough.

Stop at 10.5V and start recharging immediately..
Ratio to 20 hrs shows State of Health, how far capacity reduced.

 

[Trebor English]

Assuming the 33AH rating was for the standard 20-hour rate, a 1.5A load will be close enough.

My point is that it is not worth the cost or effort to get a 1.5 amp constant current DC load or any other test equipment to test junk batteries.  An old headlight bulb is a stretch.  The prior owner of the batteries scrapped the bunch of them.  Replacement batteries are cheaper than the test equipment to perform a 20 hour capacity test.  

The old headlight bulb cost nothing.  When the low beam burned out and I replaced it I decided to keep it.  It's no more than two cubic inches, less than a eighth pound.  Even in a mini van I have space for it.  It lives with other seldom used bits of wire, amp meter shunts fuse assortments, terminals and stuff.  It is even multipurpose.  I have used it as a bright light at night.  I have used it as a load to test the load output of my solar charge controller.  I have used it as a battery tester.  I have used it as an amp meter fuse protector by measuring the current with the bulb in series.  I don't think I'm the only one here cheap enough to keep a half burned out headlight bulb.

 

[John61CT]

If you do want to know their actual SoH, the garage style load testers aren't accurate.

The only equipment that gets close to a 20-hour load test is lab-grade costs many thousands.

But yes I agree, I'm not in any way saying it's worth bothering with such old and low capacity batts.

Plus batts purchased for UPS/standby are very unlikely to be suitable for much deep cycling.

Personally, I'd only use them for possible core exchange.

 

[Artsyguy]

If you do want to know their actual SoH, the garage style load testers aren't accurate.

The only equipment that gets close to a 20-hour load test is lab-grade costs many thousands.

But yes I agree, I'm not in any way saying it's worth bothering with such old and low capacity batts.

Plus batts purchased for UPS/standby are very unlikely to be suitable for much deep cycling.

Personally, I'd only use them for possible core exchange.

Thanks everyone for the comments and suggestions. I charged them all to about 14.3V and will make cables and link them together while I’m off for the holidays. Since these will be my first house batteries, and I’m still learning, I think since I got these for free it will be worth any time that I put into them. I’ll be sure to build my battery compartment oversized in the spring in case these don’t work out.