911 Battery Running Down

[rngpc]

I have a 85 911 and the battery will not stay charged. I do not drive it much, but have installed 2 new batteries in the last yr. - thought the first new one was just bad, so installed a second. The same problem persists, I can jump start it and drive it and the battery charges, but after the car sits for about 2 days, the battery is completely dead. Have checked/cleaned terminals and ground straps with no luck. I read another posting about the electric system being operative after the key is turned off so the windows will work. I have not checked the interior light switch in the door jamb, but plan on doing that. Anyone have any other suggestions?
Thanks in advance.

[copper]

First thing I'd do is measure the pull on the batteries while the car is off. Should be very minimal, as all you'll be pulling is a constant for the radio memory. You'll notice a pull if there is one.

I had batteries that kept dying because my horns were fried and didn't work. The horn button on the wheel was constantly activated due to a worn retainer bushing. This was sending a constant current to the horn relay, and into the non functioning horns, but I had no clue as the horns didn't work anyhow.

I would rule out an electrical problem before suspecting the battery, especially since you've replaced it once already.

The fact that there is a hot wire to the windows, lighter, wipers, or whatever else, there is no current drawn unless these items are engaged, thus requiring power. Should be only the stereo.

If the battery is okay with constant driving, the alternator's fine. The fact that it only occurs while sitting makes me believe it's an electrical problem... These can be hard to trace.

Jim

[nhromyak]

I have noticed, on my '85, if your doors have not been opened (e.g. the door light switch not contacting) the windows, locks, and something in the alarm stays "active" until the doors (or door light switch) gets opened (grounded).

I haven't checked to see what kind of draw this has though.

Do you have an alarm? These seem notorious for drawing more than there fair share from the batteries.

Good luck.

You can always check for amp draw, and pull fuses until it stops.
That sucks though.

[geof33]

I'd almost put $$ on your voltage regulator going on the fritz... Check it as well. I have also heard of a funky draw from the the ignition switch... But then, it might be that it's too late for my brain to function...

[rngpc]

Thanks for the suggestions, yes it has an alarm (factory) and the door jamb switch is notorious for sticking and the interior light not coming on. I am going to clean it and give that a try first, then do some further checking as suggested. Thanks again.

Robert Grisham
Dallas