Charging Batteries A person can usually tell that their car battery is dead when they go to turn on their car and nothing happens. There is usually no sound and no engine turnover. A battery may go dead if you keep your headlights on or play the radio for a long time while the engine is not running. An old battery might not even start up if it is really cold out. If the battery is dead, then you can't start the engine. You could be able to restore power to your battery by using jumper cables to connect it to a working battery in another car. It is always a good idea to keep jumper cables in the trunk of your car. Ju