Battery Draining overnight?

Hi people. First post on here. I have a 93 318is coupe
& the batttery is running down overnight. I can leave it
for 5- 6 hours & she starts fine but overnight & the
batttery is drained altogether. I can jump start her in the
morning & then she's fine for the day. Its baffling.
I had a problem with my amplifier a while back (it blew up
basically) but that was sorted out & disconnected.
Any ideas, its doing my head in.

Hey

I could be wrong, but its worth a try

Well first thing that came into my head was "is there anything that could be left in the night."

Heres an example...
this lady always got towed in, and always needed a boost....i kept charging, and boosting, and i checked everything else, and nothing else was wrong...So one morning she called me, and i decided to go over to her place and check it out....Turns out her driveway is on a slant, so when she parks the car is parked nose first down...Thing is, the trunk light works on a mecury switch, the light comes on when the mercury flows to one side, her mercury switch was always on when she parked, because of the angel it was parked on. So thats the first thing i would check....the angel you park.

Other than that, try and narrow your search to "what is "hot at all times" things like car alarm. Things that have current going through all the time even with the key off....

Djzeroflau

Hope you find your problems

The car is parked on a flat drive so it wouldn't be that.
I'm briinging it to an auto electrician today so I'll hope
to have to it sorted in the next few days.
Thanks for you help.

I had a problem with my 99 z3 where the battery went dead consistently over a period of 5-6 hours. It was a wet cell, so I checked the fluid levels and they were ok. I brought it to the dealer and they said there was a recall on some of the batteries for that year because of a manufacturing error. That's probably not your problem since it's an older car, but maybe the battery is just getting old.

Barring that, sounds like you've got something somewhere draining it.

Good luck.

When you park the car disconnect the battery and let it set overnight.. if the car starts the next day after, you connect the battery back up, then you may have a short...

Update on my original post above. The car has been with my mechanic & auto electrician for the last 2 days & they cant find
whats causing the battery to run down. Has anyone any more suggestions. Any help would be gratefull.

Yea, buy another car!!!! HaHa, Really though, get a simple test light, remove positive cable from battery, connect test light between cable and battery. If it lights up, then something is draining the battery. pull fuses untill the light gose out and you know what circuit is drawing the battery down. There may be more than one. Hope this helps. Later, Mark.

mark e m is right its called parasitic drain. for example during tech school our instructor had rigged up a test vehicle to teach us about this. my partner and i isolated the problem to the trunck light circuit. the problem with that was when you opened the trunk the light was on, when you closed the trunk the light was also on but of course you couldn't see that it was staying on due to the fact the trunk was closed. i climbed into the back seat and pulled the rear seat forward and sure enough the light was staying on while the trunk lid was closed. it was all due to a sticking switch for the trunk light. hope this gives you an example of how tedious this problem can be.

Hi people. First post on here. I have a 93 318is coupe
& the batttery is running down overnight. I can leave it
for 5- 6 hours & she starts fine but overnight & the
batttery is drained altogether. I can jump start her in the
morning & then she's fine for the day. Its baffling.
I had a problem with my amplifier a while back (it blew up
basically) but that was sorted out & disconnected.
Any ideas, its doing my head in.
SOUNDS LIKE YOUR ALTERNATOR ISNT HOLDING CHARGE ANY MORE. CHECK YOUR ALTERNATOR. GOOD LUCK!