by: PAUL BRAND
- Updated: January 18, 2013 - 3:58 PM
Q I have a 1997 BMW Z3 roadster purchased used in 2001. Since Day One, the battery will go flat if I leave the car sitting for more than a few days. Two different BMW shops have been unable to diagnose the problem. The battery that came with car and a new one needed to be replaced because of so many deep discharge cycles. I installed a battery cut-off switch to save the third battery and make sure the car will start when I want it to. Of course, I need to reset the clock and the audio system settings each time. My brother, an automotive mechanic, says the first thing he would check is the alternator because the diode sometimes goes bad and allows a small reverse current flow. Have you ever encountered this?