Will Idling Car Charge Battery?

Assuming the alternator, engine, belt, and battery are all in working order, then yes, a car battery will charge when idling. The only caveat is that it doesn't really “charge” that fast. This is solely due to the fact that the engine doesn't have a load on it when your car is simply idling.

How long do I need to idle my car to charge the battery?

Remember: After you've done a jump start, you'll need to keep the vehicle's engine running for around 30 minutes to allow the alternator time to charge the battery sufficiently.

Will a car sitting in idle charge the battery?

Does the Battery Charge if You Let the Car Idle? The simple answer to this question is yes, your car's battery will start to charge as long as your engine is running.