Expert: Brad Sears - 9/23/2011

Question
Battery runs down when parked. If disconnected, no problem. Just reconnect and car starts right up.  Any thoughts on how to find what is draining the battery?  Thanks.

Answer
The most common causes in that era were:
1. Sticking points in the voltage regulator
2. Trunk, glove box light, or under hood light staying on
3. Stop lights staying on
4. Voltage drain across a dirty battery top

To check the voltage regulator connect a test light to the large "A" terminal of the generator. Start the engine and run it up at a fast idle for several minutes. Shut the engine off and check the test light. If it is on the voltage regulator should be serviced or replaced.

To check the lights listed in number 2, open each hatch and immediately feel the bulb. If it is hot to the touch it has been on. The bulb takes a minute or two to heat up and you need to be quick.

Number three is simple, just check the back of the car.

To clean the top of the battery with backing soda mixed into a runny paste and bush the battery with it. If the top is dirty the soda mix will bubble up. Then rinse and clean the cables. The best thing to stop corrosion on the terminals is still Vaseline.

If there are any aftermarket accessories installed, check them by pulling the fuse when shutting down until you find the offender.