How To Know If Your Car Key Battery Is Dead. Place the key fob there and while depressing the brakes press the start button and start the engine. While you dont need the key fob battery to start your car you do need it for any remote functions that come with your vehicle.
Another indication of a dead battery is that you cannot turn on the interior light of the car. If its one of those two placing the blame can be relatively simple. Either way key fobs run on batteries.
Turn your car on and let it run.
Its hard for an alternator to charge a fully drained battery because they werent designed to charge batteries from a state of full discharge. If your car wont start its often due to a malfunction of either the battery or the alternator. Its hard for an alternator to charge a fully drained battery because they werent designed to charge batteries from a state of full discharge. Another indication of a dead battery is that you cannot turn on the interior light of the car.
