I got my car out of the shop a few days ago and I’ve been having a problem with the alternator since. While the engine is cold (most times) the battery charges as normal but after about 10-15 minutes of driving the battery indicator comes on and battery drains. Also, revving the motor to around 35-4000rpms will turn the light off and charge the battery. I checked the belt tension, it was loose but after tightening it only brought me to where I’m at now. So I’m thinking either the alternator is going bad or the battery is shot. Any help would be appreciated.
Pull the battery out and test it. Let it sit a day then test it again. Take it to a parts store and have them run a mult-meter across the 2 terminals while its charging. Im going to guess its the alternator. Should say about 14.6 while charging. And around mid 12’s while turned off.
Thanks for the advice, my first guess was the battery because of the indicator only comming on when the engine was at running temp. Who knows, I’ve had alot of weird problems in the past.
Go to a parts store like carquest. They have a reader that hooks on your battery terminals while the car is running and will tell you if its the battery or the alternator, takes like 3 mins.