There are may causes to a "dead battery" in your car or truck. Most go bad simply by age. Most batteries last 5 years. You should have your "battery tested" at least with every time you have an "oil change". A battery can show signs of getting weak, or simply just fail. Other causes could be damage to the battery caused by over charging by the alternator. So when your Ford, Honda, Toyota or Chevrolet shows signs of "slow cranking" or "no start" have your "charging system check" done.