What can cause battery to run down in a 1993 Buick lesabre?

Answer 1

Normally there are 3 things that can cause the battery to run down. It can be the battery itself has a dead cell which means you must replace the battery. It can also be you have a defective alternator which is not charging the battery. Another possibility is a parasitic drain on the battery. This can be caused by a light that is on somewhere. Could be a courtesy light, under hood or trunk light, brake like, etc. Can also be that you have a relay that is stuck on the vehicle some work. Any of these things will cause the battery to run down. Remove the negative cable from the battery and see if you can fully charge it with a battery charger. Let the battery sit overnight and check the charge in the morning. If the battery is dead it has a dead cell and must be replaced. If the battery is fully charged connect the negative cable back up and start the engine. With the engine idling check the voltage at the battery with a volt meter set to the 20 Volt DC scale. You should read from 13.5 to 15.5 Volts DC if the alternator is functioning properly. Any less and the alternator is defective. If both the battery and the alternator are good start looking for a light that is on or a stuck relay.