Can A Battery Read 12 Volts And Still Be Bad. The actual resting voltage or the voltage a battery will settle at 12-24 hours after being removed from the charger is closer to 21 volts per cell or about 64 volts for a 6v battery and 127 volts for a 12v battery. How do you tell if its your alternator or your battery.
Temperature also has an affect on the amps so your battery could be reading above 12V but still wont crank because the amps are too low. If the battery is bad then you would notice the lights going REALLY dim when you try to start the car. Rather it is voltage under a load that is important.
Yes an old battery may very often show 12 volts on testing with a voltmeter however as soon as you put a load on it such as a starter motor the voltage will crash since it cannot deliver the amperage the starter needs.
When the engine is running the alternator should be charging right around 141-146vdc. The voltage doesnt have to differ much from 126v for it to indicate a discharged battery. That means it is bad probably has a dead cell correct. If the battery is bad then you would notice the lights going REALLY dim when you try to start the car.
