This section used in it's entirety is from a larger article and
comes from autobatteries.com



When your car won't start, you might jump to the conclusion that you have a dead battery.
You should realize something else could be the culprit.
• Do you have a bad starter or solenoid?
• Is your alternator bad?


Your battery could also be discharged, which simply means it needs recharging. Check around to see what may be causing the battery to discharge.
• Has your car been sitting for a long time? If so, the battery may discharge by itself.
• Are there drains on your battery when your car is turned off? Check accessories including cell phones, radar detectors, GPS, TV, or computers. Even car alarms can impact your battery.
• Have you left your headlights, dome light, glove box light, or trunk light on for a long period of time? That can cause an excessive drain on your battery.
• Is it extremely hot or extremely cold? Both high and low temperatures can take their toll on the battery's charge.
• Is there an electrical short anywhere in the vehicle?
• Have you modified your vehicle with air conditioning, power boosters, advertising signs, or additional radios?


The problem could also rest in something around your battery.
• Are your terminals or battery clamp corroded? If so, your battery won't charge properly.
• Is there a loose ground wire giving you an intermittent connection?
• Do you have a cross-threaded bolt on your side terminal? That could cause a loose connection.
• Is there a loose or worn belt? That can make your battery work too hard.
• Is your voltage regulator functioning? If not, your battery could overcharge or undercharge.You should also check your battery for related problems.
• Is your battery installed correctly? An improper holddown or a lack of holddown can cause excessive vibration and internal damage to the battery.
• Do you have the right battery size? If your battery is too small for your vehicle, it may not function correctly.