Battery Draining (E34)

[Bimmergal30]

Hey BMW pals,

Can someone tell me if they have problems with a battery that keeps draining? I recently replaced my alternator and bought a new battery in the last week. After the car sits for a few hours or overnight the battery drains could it be a vanity light or radio or something staying on in the car? I have a 1990 525i that's hot on the road I can't have my baby sitting up crippled pls help??



10-4
BIMMERGAL30

 

[RANDY P]

You sure the new alternator is OK? Double check your charging voltage. If it's showing 13.8+ at idle you're good. My experience with reman alternators (any make) suggests this as a possibility.

Assuming it passes the output check, then start looking for things that are stuck on. If your battery is going dead overnight, it's probably not something like a vanity light or a radio on that's doing it. It's more significant then that. If you have the ability, check amperage draw with a volt ohm meter on the battery. If you're seeing significant draw, start removing / replacing fuses from the fusebox until the drain is reduced. Pull the right fuse, and the draw will stop.

Also check to see if like your fuel pump relay isn't shutting off or perhaps something wrong with the keyswitch, or even something dumb like a bad brakelight switch keeping the brakelights on. Pulling fuses will usually uncover it's something like that.

Good luck

rjp

 

[Bimmergal30]

Thanks for that info, when the alternator first got put on it was putting out 13.8/14 then we thought all was good and I went to work the next day let the car sit for 8hrs went out and dead battery had to get a jump. I know I have a bad viper alarm system on the car that I don't have remote for and it has a kill switch so maybe I'm thinking it could be stuck in an on position or something. I am going to go to the BMW dealer and get new fuses and replace them all to rule the fuses out but I think first I am going to have the alarm completely removed today and see what happens from there cause to have to keep switiching and alternator can be very costly. Do you think an electrical short would cause the alternator to not function at it's full capacity? I keep seeing a light pop up on the dash that says BREAK LIGHT CIRCUIT+ does anyone know what that means??


10-4
Bimmergal30

 

[RANDY P]

1) Check your charging voltage again

2) Alarm system just sitting there isn't going to kill the battery overnight- the siren would have to wail for that to happen. That brakelight circut warning - where on the dash is it? Like the parking brake light? could mean master cylinder failure - but then you know since you have no braking power.

I know the e34 - my brother has one- lemme know where that light is.

 

[epj3]

1) Check your charging voltage again

2) Alarm system just sitting there isn't going to kill the battery overnight- the siren would have to wail for that to happen. That brakelight circut warning - where on the dash is it? Like the parking brake light? could mean master cylinder failure - but then you know since you have no braking power.

I know the e34 - my brother has one- lemme know where that light is.

If you knew the E34 you would know she ment the LCD display under the gauges... The only way a bad master cylinder would throw any light or warning would be if it leaked enough to show low brake fluid.
Could be a faulty LKM (Controls all the lights), But it DEFINITELY sounds like there is a short in the brake light wiring or circuitry which could cause the battery to drain overnight.

The only reason that COULD be wrong is the brake light circuit should be closed when the ignition is off (hence the reason your brake lights dont work when the car is off).

Last note - some of the brake light units were faulty in the e34's. Pull out brake light bulbs and see what happens.

You can also try a trial-and-error. Try pulling all accessory fuses the next night, and see if it still drains.

 

[RANDY P]

If you knew the E34 you would know she ment the LCD display under the gauges... The only way a bad master cylinder would throw any light or warning would be if it leaked enough to show low brake fluid.
Could be a faulty LKM (Controls all the lights), But it DEFINITELY sounds like there is a short in the brake light wiring or circuitry which could cause the battery to drain overnight.

The only reason that COULD be wrong is the brake light circuit should be closed when the ignition is off (hence the reason your brake lights dont work when the car is off).

Last note - some of the brake light units were faulty in the e34's. Pull out brake light bulbs and see what happens.

You can also try a trial-and-error. Try pulling all accessory fuses the next night, and see if it still drains.

Actually dude, my brother's car doesn't do weird $hit like that so as a matter of factly, I've never seen the indicator firsthand. That statement was made since I do have access to the car firsthand if I need to take a look.

rjp

 

[[email protected]]

heh i just fixed that problem for one of my customers batery would drain overnight turned out to be the trunk light

 

[Bimmergal30]

Hey Bimmer Pals,

I am so happy my mechanic and I finally found out what the problem was last weekend, it was a bad fuse in my fuse box that goes to my compartments lights in the inside of the car that was staying on all the time. We realized that my glove box wasn't closing properly so that light stayed on the way we found out was by putting a meter on the batter that checks the alternator and battery level of charge. It was very interesting to have that solved cause we actually like watched the meter hit from 12.6 while car is running with the fuse still in then when we turned the car off we could see the drain start to go down!! the meter went from 12.6 to like 11.5 in less than 20 minutes what a drain I could see how the battery would discharge after a few hours of sitting.

So once we started checking and pulling all fuses my mechanic noticed that once he pulled that one fuse the meter SHOT UP TO 14.25 in like 2 min so no we did not put that fuse back in. I am in the process of having a new glove box put on so that the light goes off when it is closed and not stay on but till then THE FUSE STAYS OUT LOL....... can you believe I went through about $500.00 in a week changing and alternator, new battery and service just to find out about a $1.25 fuse lol.....well the good thing is it's running gooooood! just got her oil changed and ready to hit the road bimmer style.


THANK YOU ALL FOR YOUR CONTINOUS HELP AND EFFORT TO SOLVE THE PROBLEM

BIMMER PEOPLE GOTTA LUV EM'

PEACE AND LUV,
BIMMERGAL30

 

[lilbimmer]

1

2) Alarm system just sitting there isn't going to kill the battery overnight- the siren would have to wail for that to happen.

I am not so sure abou that! My father has a MB and his after market alarm would drain the battery w/o hearing the alarm. This would happen to him when he laft the car parked for several days at a time!

 

[RANDY P]

I am not so sure abou that! My father has a MB and his after market alarm would drain the battery w/o hearing the alarm. This would happen to him when he laft the car parked for several days at a time!

Was dad's battery getting tired? Most newer cars thanks to memory features and whatnot esp. with an older battery will do that. The dealer's knee jerk response is to blame the alarm system. They'd blame your dead battery on your aftermarket wheels if they figure you'd buy off on it..

My early 911 sits in a heated garage with no electronics other than a basic alarm that sits unplugged since the car is parked for months at a time, and even with ZERO electronics except the factory clock, it will discharge the Optima Yellow top deep cell installed within 14 days. This is a car that has nothing on inside. A later Benz with all the typical crap inside will undobtedly burn through a battery much quicker.

Fact is, the typical (as directed by alarm manufacturer's advice) basic install will draw less amperage than the vehicle's clock. In a typical basic alarm install, there is only 4 wires that actually need to be tapped into the factory wiring *(ignition sense, door trigger, starter disable/ cut and relay installed, and voltage for the parking light flash). Don't do starter disable and you don't even need to actually cut anything - all wires stay in one piece. No current goes through the system except for the LED, and that isn't even close to powering an analog clock. If the alarm is triggered, then voltage to the parking lights and siren get tagged on.

Simply isn't possible, unless you really freaked the alarm with all kinds of lights and whatnot.

rjp

 

[inspectkta]

My battery drains every night. I hear a motor going in the dash, when I smack the top of the dash it shuts off for a while and then comes back on. Has anyone had a similar problem, and how did you fix it? Tree

 

[tyang76]

My battery drains every night. I hear a motor going in the dash, when I smack the top of the dash it shuts off for a while and then comes back on. Has anyone had a similar problem, and how did you fix it? Tree

inspectkta,

Did you fix your battery drain problem yet? If you do please let me know because I'm having the same issue as your car. I have a 2001 530i and the battery drain overnight and hear a fan motor running after the engine is shut off.

Any help from you is greatly appreciate.