what voltage should a car battery read if it is good
3) Depending on the battery condition, the voltage that will allow the engine to turn over changes. A battery with 5 good cells and one bad cell may only read ~10 volts but still be able to turn the starter. A battery with all six cells in good shape that reads 11 volts, however, would almost certainly not be able to spin the starter. 4) Yes, when the car is running the alternator puts out ~13.8 volts.