My son's 1999 sl2 sedan has an issue thats's driving me nuts. car starts and runs well except after about 30-45 mins will stall and lose electrical power. guages go to 0 no radio intermittent weak chimes. Car can be push started and will run for a few minutes then stall out. Some missing noted. If it sits for a couple of hours it will restart with a jump and repeat the process all over. Battery checks out ok. Any suggestions?

 

Your battery does not have a full charge -- either

the alternator is not going at full output and not fully charging battery, which will eventually drain and not be able to supply sufficient current to run the car.

Or

the battery itself may not be holding the full charge coming from the alternator --battery may have a cell going bad.


What's the voltage across the battery terminals with the car at rest (off) and what's the idling after startup (with no accessories turned on -- before the funniness)?