Testing AGM batteries???

jackhartjr · June 05, 2016, 03:30:24 PM

Hi folks, what kind of testing unit do I need to test AGM batteries to make sure they are still good?
Thanks in advance!
Jack
BTW, the guy at Denka batteries said the only way to test them is with a $700.00 Carbon Pile unit! I suspect it can be done for a lot less!

Tony LEE · June 05, 2016, 04:20:50 PM

Depends what you are testing for = engine cranking ability or use as a power source for living quarters.

For motorhome use you can test the storage capacity with a couple of headlight bulbs, a clock and a voltmeter and a bit of patience.

TedCalvert · June 05, 2016, 05:53:33 PM

I like the way you think, Tony LEE!

jackhartjr · June 05, 2016, 06:17:07 PM

I have 10 group 31 AGM batteries in my truck that run a 10,000 BTU Dometic APU. When the bank gets down to 10.5 volts, it is designed to shut down so I can still crank the truck. It charges during the day with a 320 amp, 3 stage alternator. I want to be sure each battery is still good!
To keep it bus related, I will have the same batteries in the bus!

LuckyChow · June 05, 2016, 06:33:31 PM

There are a couple of the electronic testers that will check an AGM. Most of the common ones I've seen won't. The ones that will cost about 30% more as I recall.

TomC · June 05, 2016, 06:44:11 PM

Jack-isn't that tiring carrying 10 batteries back and forth from the bus to the truck? (LOL)

jackhartjr · June 05, 2016, 06:47:09 PM

Tom, that's just wrong! LOL

luvrbus · June 05, 2016, 07:48:38 PM

Use Tonys method,I had a out fit ship me a Bosch Bat 131 without asking a price when I received the bill I had to sit down for 5 minutes till my heart slowed down and of course they had a no return policy on testers after 10 days but it is a handy gadget

HB of CJ · June 05, 2016, 11:02:29 PM

It does matter if your AGM batteries are cranking or house. There is an old fashioned testing procedure that works just fine. The only problem is that if you are testing the capacity of HOUSE AGM batteries, this test may take most of one day ... and nite.

It requires a good multi meter, a clock or watch and a proper size and proper length of heavy gage insulated wire. The process is rather involved and somewhat daunting for the first time doer. PEM if you want to learn more. The heavy wire does get very hot.

chessie4905 · June 06, 2016, 04:49:51 AM

Run the AC till it is cut off by low voltage. Then disconnect and check each battery with a volt meter

Might want to read up on comments on these battery testers. One or two might do the job. I don't own one so don't have personal experience.
http://www.harborfreight.com/catalogsearch/result?q=Battery+tester