Battery Charging

[DenverGladiator]

Battery testing seems to be a voodoo art. To do it right takes time and special equipment. I expect your battery is OK for most uses, but will not pass some test run by the Jeep systems.

Besides that, I haven't seen anyone qualify battery performance by measuring cold cranking amps. Who did the test and did you see their equipment?

I had to look up testing for CCA. Here is one article I found.

How To Test Cold Cranking Amps With A Multimeter - All About Cars News Gadgets (cars-care.net)

I had AAA come out this morning to install as I planned to replace the main battery now that I replaced the Aux battery. He ran a test on the battery before it had been started, then started the engine. It dipped down to 12.4 when ignition started then was a consistent 14.5 as it idled for 4+ minutes.

I don’t know enough about how he tested, but he admitted his test does not show everything. He said battery looked great, was 749 CCA and 76% battery life (said some batteries he installs run less than 76% new?) He said battery is an AGM and should get about 5+ years. He recommended taking it to a shop for a more thorough test, but he also wondered if something besides the main battery was the problem. He said he could install a battery for just under $300, but I’d be better off getting an AGM elsewhere with a 5 year warranty.

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[Mr._Bill]

I had AAA come out this morning to install as I planned to replace the main battery now that I replaced the Aux battery. He ran a test on the battery before it had been started, then started the engine. It dipped down to 12.4 when ignition started then was a consistent 14.5 as it idled for 4+ minutes.

I don’t know enough about how he tested, but he admitted his test does not show everything. He said battery looked great, was 749 CCA and 76% battery life (said some batteries he installs run less than 76% new?) He said battery is an AGM and should get about 5+ years. He recommended taking it to a shop for a more thorough test, but he also wondered if something besides the main battery was the problem. He said he could install a battery for just under $300, but I’d be better off getting an AGM elsewhere with a 5 year warranty.

Unless you disconnected the Aux battery, the test is not accurate. The Main and Aux batteries are paralleled together all the time, except during the startup Aux battery test and when ESS has the engine turned off.

The least expensive option for the Main battery is usually at Costco or Sam's Club. They provide a three year warranty and will install it for you.

 

[Andy29847]

What Mr Bill said. The AAA tech probably didn’t separate the 2 batteries.

I felt like my visits to the dealer generated more trouble than they fixed. The techs at my dealership either don’t understand the 2 battery system or they were busy padding the warranty work to feed their kids.

I have spent some time trying to solve the “best battery” solution. Info from the internet searches I did seems to be a couple of years old. I decided on 2 criteria. Cold cranking amps should be 800 amps or more. The warranty should be 3 years or more. The Everstart battery I found at Walmart seems to be a class leader in those categories and is less than $200.

Good luck!

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