Common Causes of Battery Failure

If a battery has tested good and continues to discharge in service, the following are possible causes to the problem:
^ Vehicle accessories left on.
^ Conditions in the charging system such as slipping belt, high wiring resistance, faulty generator/charging system.
^ Blown fusible link between starter and generator.
^ A vehicle electrical load exceeding the capacity of the generator.
^ Extended slow speed driving with many electrical accessories turned on.
^ Conditions in the vehicle electrical system such as shorted wires or high parasitic current loads.
^ Loose cable connectors, loose hold downs, or improper charging of a previously run down battery.

NOTICE: Do not check for battery terminal tightness by rotating cable while attached to the battery. This could cause the battery lug face to be damaged and result in a poor electrical connection.

^ Corroded or loose cable connections or other cranking system conditions.
^ Long periods of vehicle storage without disconnecting the battery. Parasitic loads can discharge a battery in 4-6 weeks.

IMPORTANT: A dead battery is usually a symptom of another problem. Fix the problem; don't just charge the battery.