4xe - Accurate 12V Battery Testing

[GATORB8]

My wife has the Jeep out of town, or I'd test this myself. We've got the standard battery tell-tale, a dash lit up like a Christmas tree, and fifteen DTCs.

Only five months ago, I replaced the battery with Autozone's best available replacement. When the OEM battery failed, it passed the Oreilly's voltage test when I started getting symptoms.

Now, I had my wife take it to Autozone for warranty replacement and the battery "passed".

That got me thinking, there's basically two reasons it could be passing, the voltage is floating high after being charged in route, or the Jeep is actually still charging the battery with the DC-DC charger.

Anyone had one actually fail the test? Thinking of having her tell them to disconnect the battery or pull the charger fuse and test again, but, of course, she's not real keen on some prick telling her to go to the dealer again.

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[BigMaCro]

I don't know what these parts stores use for battery testing. The "correct" way is to use something like a Midtronics tester, but of course like anything it also depends on the person using it correctly and running the appropriate tests.

https://www.midtronics.com/blog/which-battery-test-technology-is-right-for-you/

 

[GrayWolf.Overland]

My wife has the Jeep out of town, or I'd test this myself. We've got the standard battery tell-tale, a dash lit up like a Christmas tree, and fifteen DTCs.

Only five months ago, I replaced the battery with Autozone's best available replacement. When the OEM battery failed, it passed the Oreilly's voltage test when I started getting symptoms.

Now, I had my wife take it to Autozone for warranty replacement and the battery "passed".

That got me thinking, there's basically two reasons it could be passing, the voltage is floating high after being charged in route, or the Jeep is actually still charging the battery with the DC-DC charger.

Anyone had one actually fail the test? Thinking of having her tell them to disconnect the battery or pull the charger fuse and test again, but, of course, she's not real keen on some prick telling her to go to the dealer again.

i've been dreading this scenario ever since the arctic cold snap. Does it give you any early warnings before its full-on christmas lights? I am still on the stock 12v, and I wonder if I should proactively change it out at the earliest.

 

[BigMaCro]

i've been dreading this scenario ever since the arctic cold snap. Does it give you any early warnings before its full-on christmas lights? I am still on the stock 12v, and I wonder if I should proactively change it out at the earliest.

I am coming up on 2 years with my OEM battery. I haven't had any problems. I carry a jump starter with me, but haven't had to use it. I probably haven't taxed it very much. I have winched only a few times, and only recently installed a fridge but it doesn't work very hard.

I believe @GATORB8's battery failed after an epic cross-country road trip to Moab and towing a trailer. I imagine his loads and stresses to the battery were much more substantial than most.

That being said, I have heard of failures with normal driving on unmodified vehicles too. I think it's pretty much a crapshoot whether or not you end up with a defective battery. I don't know of there's really anything "bad" about the design of the factory battery - it is in fact an AGM by East Penn, the maker of many battery brands you've heard of.

So, I don't suggest to replace it without cause. If you do, Odyssey or Optima would be good options. The size is 94R-H7.

 

[PatriotX]

Changing out the OEM 12v was my first mod, after reading early reports of the light shows.

I feel that the hybrid charging strategy is magnifying an already existing problem with these batteries.

 

[GATORB8]

Soo… I had my wife return to autozone and have them disconnect for 10 minutes prior to testing, the damn thing still passed.

Now for the fun part, I wasn’t leaving her with a battery I know has a chance of stranding her this far away for me, so I tell them I’ll just buy the replacement and mess with the warranty later. She buys the new battery, then they refuse to install it because they are “not certified to work on hybrid vehicles”. So much for southern hospitality, my wife is 5 foot nothing, and, of course, can’t swap a heavy lead acid 4’ off the ground.

We’ll have a friend swap them out before she leaves, but the cherry on top is we cleared the codes again, and not one light has returned.

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