Car battery is dead overnight

Realizing that your car battery is dead and won't start your car is one of the signs you may have a problem with your electrical charging system. Of course batteries don't last forever and should be load tested to make sure they are still holding a full charge annually. You should replace your battery every 3 years regardless. Some batteries will begin to give signs that they are failing, like slowly turning over your engine when starting, while others work fine right up until the time they fail completely. If you have to repeatedly jump start your battery, it is time to see if the battery is the problem by having it load tested. If the battery is good, check to see if you have a continuous battery drain somewhere or the charging system is not working properly. Some cars have a voltage gauge where you can see if it is charging at over 14 volts while the engine is running. The smallest light left on over night will drain a brand new battery too.