Defective, new, 12v?

[rhieb]

In Feb ‘26 I ordered a new 12v from Rock Auto. It was Preventative maintenance, as my original was acting just fine. But I figured at 36 months a new one was a prudent step to avoid unexpected issues.

On the bench, with a DMM, the New one measures 13.1 v out of the box. It was about 13.8 after a night of AGM trickle charge. I installed it per instructions here on this fine forum. It seemed ok for about a month. Then , one morning, I noticed anemic chimes and strange errors. I checked obd2 data, and it showed 0% SOC.

I drove to work, let my car “idle” that day in the parking lot and it got to 25%. I took it for a long drive, it got to 70%. Then I got in the car next morning and it was at 35%. I pulled it out and put the original back in. (For the month that the original sat on the bench , it held a 13+ v. ) The original has held fine, hovering between 85 and 99% SOC.

I put the new one on the trickle charge, and after 24hours, it measures 13.5v. Next morning it was at 12v. Next couple days it dropped to 11.5.

Question: Has anyone else received a defective, new 12v, and how did they claim the warranty? Take it to Ford dealer? (That’s what Rockauto is saying.)

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[Lackadocious]

The only reason I would guess Rock Auto is telling you to take their battery to ford is to have it tested. Any auto parts store should be able to do the same test. Depending on the battery manufacture, the exchange period is 12 months - 48 months.
https://www.rockauto.com/docs/warranty

 

[Mach-Lee]

If you fully charge the battery, but then it goes down to 12V overnight on its own (while completely disconnected from anything) then it is a bad battery (internal short). It happens.

Ford will not warrant a battery you did not buy from a dealer, so if RockAuto won't take it back, you'll just have to take the loss and buy another one. Basically you have to return/warrant the battery through the outfit you bought it from.

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