Battery very weak after driving any distance. Have to wait 20 min before restarting.
2002 Audi A4 3.0 Manual.
Car starts fine in the morning. If I stop to get gas or stall it, the battery suddenly becomes very weak and barely has the energy to restart the car.
However, if I let the car then sit for 20 minutes, the battery regains enough energy to start the car.
I have no clue as to what is going on.
Get the alternator checked, it likely not putting out enough to keep battery charged. Any auto parts store can do these tests for free (at least in the USA).
The alternator was charging at 14.3 volts. Battery voltage drops to 8.5 when starting. For some unknown reason, the car is harder to crank when warm than when cold. Replacing battery fixed problem. Battery was probably 6 years old.
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