Battery or Alternator

[BMF]

Hi guys
so.
I know the battery on the car is not fresh new. but the still starts so
I assume it's still working.
However When I drive a little bit and go a bit high rpm. the car stalls and the battery gauge goes lower than 12v and it wont start.
so I turn off the headlight and it goes a bit higher ( close to 12v) and I wait a minute, and it starts again.

Do you think its just the battery should be replaced or the alternator not charging enough .????

[EtienneGignac]

My guess would be the alternator. Technically, you're supposed to be able to remove the battery completely when the car is running.

There might be a low battery protection in the ECU that shuts off everything when a low voltage is detected so that you have enough to start it back up again.

And that happens regardless of how long you let the car run to charge the battery ?

[Joey]

voltmeter time!