1989 911 Carrera 4
Didn'texplain my situation very well last time...

Having a battery drain on my 911. Techs have checked battery test load, battery circuit, etc. All passed. New alternator. Replaced broken window switches which was told could drain battery. (They only replaced1 on Dr. side and the one on pass side.) Still dead battery in morning. Anybody have any ideas on what could be causing this?

I can jump the car and take for spin. Next morning will start, other days no. Will start for 3 mornings in a row. Then not. Took for spin to gas station 3 miles away, started back up fine then topost office300 ftaway. No start, low power from battery. Jumped last nite, dead this a.m. It will turn over once/twice but then gone.

Just all seems bizarre. If it's the switches are draining the batterywhy wouldn't it be dead in a.m., not afterdriving it for10 min.?

Alternator tested out fine and no orther "drains" could be found.

I'm just dazed and confused by all this.[&:]

Appreciate the advice.
Thanks,
John

 

Electrical problems on cars are not so easy to solve. But you have to start with your battery. Take your battery out of the car,get a good automatic charger and charge the battery over night. No fast charging! Take the charger off the next morning and leave the battery alone for a day or two. You will see, if your battery holds the charge. I had a similar problem several times with a brand from a big department store, after I switched the brand, no more problems. If your battery turns out to be good, put the battery back into the car, put a multimeter on the battery and start the car, your batteryvoltage should not go under 10 V during starting, if it gets under 10 V, your battery is bad. If that is ok, leave the multimeter on the battery, take all the fuses and relais out and put them back one by one and watch the multimeter - the ignition key has to be out and everything switched off - if you have adrainage somewhere in the wiring, you will see a small moving on the multimeter. Sometimes the high power wire connection to the starter solonoid is dirty from road grim and oil from the engine, that's creating a nice drainage from the battery. And at last, take one of the battery cable of the battery, everything switched off, then just touch the battery pole with that cable, if you have a drainage, you see an electric spark, you have a bright spark, you have a big drainage and vs.vs. Good luck.