Car Battery Sounds Dead but isn't

[Lilylilyone]

Hello,
I've got an issue with my car battery. The multi-meter reading shows 12.5v but once every 20 or so starts the battery suddenly goes low and doesn't have enough power to start the starter motor. I then bump up the voltage to 12.7v and it starts fine. Then after running the engine for a while the voltage goes back down to 12.3 to 12.5 but it starts fine again - until the next time. I guess my question is, is there another reason why a battery might behave like its lost most of its power when it hasn't.

[kevtherev]

Hello,
I've got an issue with my car battery. The multi-meter reading shows 12.5v but once every 20 or so starts the battery suddenly goes low and doesn't have enough power to start the starter motor. I then bump up the voltage to 12.7v and it starts fine. Then after running the engine for a while the voltage goes back down to 12.3 to 12.5 but it starts fine again - until the next time. I guess my question is, is there another reason why a battery might behave like its lost most of its power when it hasn't.

Batteries can be deceitful.
They can show you 12.6
But if a cell has been compromised it will have lost its cranking power.

Batteries that have lost a cell or have a weak cell are generally quick to charge up but quickly lose the cranking amps.
Any drain on it will put it below cranking capabilities pretty quick


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