On two occasions in the past 3 months (January and last Monday), I have left work to find the car dead. No lights, no clock, no radio, won't start. I get a jump and it cranks right up. Clock and radio reset, so all power was lost. The battery is 2.5 years old, so my first thought was that it was dead. My ride home is only 10 minutes, which is not enough to charge a dead battery, but sure enough the car is fine the next morning and on. It's almost like something zapped the car into not starting, and once the jumper cables are on, it acts fine. So, I'm wondering, could this be a grounding issue? There is a ground strap going from the battery to a metal lug on the body, and while there is a bit of corrosion, it all looks fine. Any relays that could do this? I changed the master relay less than a year ago, and the distributor has been changed as well. I'm stumped, but I at least carry jumper cables with me.

 

You may have an intermittent short from positive to ground somewhere that drains the battery. Check over the cables for worn insulation. If you have a multimeter, remove the positive cable and check the current with the car shut off, there should only be a few milliamps for the computer.

 

replace the battery clamps and clean the battery posts. check that the ground wire in the back of the altinator and all other wiring is conneced tight and that the wires are not damaged there. my bet is its the battery clamps. theyre not getting a good contact on the positive post. your ride home is too short to charge a flat-lined battery. why did it start the next day? if your alt wires are loose, why did it run off the alt to get you home? what it is is this, you have bad battery clamps. when you put jumper wires on your battery clamps you shift the clamp tight. it stays like this and starts your car in the morning.