A dead cell in the battery itself will cause it to drain overnight. The battery must be replaced if it has a dead cell. Also any light that is on will cause this. Brake, dome, under hood, trunk, glove box, etc. A relay that is stuck closed is another cause.
a battery
dead battery , poor cable connection to battery
battery no longer can store a electrical charge, a charging system failure, a parasitic draw,
A short in electrical system within the battery where two cells short together.
The main cause of battery drains is a bad electrical system. The electrical system is normally powered by the alternator and once the alternator goes bad the battery has a hard time holding a charge,
If the ignition isn't firing then you're looking at an electrical problem: Bad spark plugs, distributor, cables or battery. If you're frequently draining your battery and needing jump starts, the alternator could be failing as well.
A car battery in any car would drain due to a short in the electrical system.
i think you are having problem with your alternator its not charging your battery
Overcharging. Check your electrical system to see if the alternator is overcharging the battery. It can also be the battery is defective and needs replacing.
A car battery causes the headlights to shine
My understanding is that you are hearing the starter "click" but it does not engage. If that is correct your answer is: Typically either 1. the battery isn't fully charged (either a problem with the charging system, something is running the battery down or the alternator isn't charging properly) 2. a poor electrical connection somewhere between the starter and the battery or 3. a problem with the starter or solenoid.
It is very hard to diagnose electrical this way. However, it is most likely a bad battery or a bad ECM module.