Deano

Something in my car is draining the battery overnight.

I had a 1.5 year old battery that seemed to be working fine until the other morning when car was completely dead. No lights, iDrive, starter function, just dead. The night before I had just gone through one of those touchless car washes w/ the undercarriage spray. I wondered if water got into something it shouldn't have. I put the battery on my charger for about three hours and the charge indicator hardly moved. This battery was still under warrantee, so I returned it to Batteries Plus hoping to exchange it. They required 24 hours to test it before a replacement under warrantee could be considered. As I was about to leave on vacation and needed my car to function the day I returned, I just bought a new one, and if they found mine faulty, they could reimburse me.


Back from vacation I install the battery, use the car and everythings seems fine. Next morning the car with the new battery is dead again!

I searched this forum and others and found this from another forum from 2009 in the U.K.:

"The E60 battery negative lead has an Intelligent Battery Sensor built into it,the early ones were prone to moisture causing an internal fault inside it,just above its location there is a vent that can let a little moisture in. The new IBS's are completly waterproof and i haven't had to change one yet. If the sensor is faulty it can stop the car going into sleep mode and actually cause the battery to go flat,the complete opposite of its invention.
The dealers have an energy diagnosis test that highlights if there is a battery drain fault,but if that shows up o.k,i would suspect the i.b.s is faulty.
If a battery has gone faulty and it is replaced,then we have to register it in the ibs's memory so it can start monitoring the battery drain accurately again.
I've seen cars that haven't had a new battery registered keep putting up check control messages because the ibs is confused.
If u disconnect the little red wire on top of the ibs,(its power supply) the battery then goes back to just being a negative lead again,so you could try that and if the battery doesn't go flat then u could buy an ibs
Strictly speaking if you fit a new one you are meant to carry out a full software update.
You could try ur local dealer for a goodwill claim,its worth a phonecall to them"


This is interesting as my first problem occured the morning after a heavy spray touchless car wash.


I am out of warrantee (2004 545i) and I have a tri amplified non-stock stereo system. I am weary about handing this to the dealer w/o at least trying to disconnect the IBS sensor overnight and see if it's faulty. I've read about others who have had dealers charge over 10 hours labor to diagnose, and replace xyz module$ w/o success.

My main question, If I use the car with the IBS disconnected, will it cause harm or set codes?

Thanks,
Dean

luigi524td

Did you have the alternator output checked? Maybe that's the root of the problem. I think the labor to remove and replace the IBS is about one hour ... the part may be about $200 - check here http://fwd4.me/07gH . Can't comment on the effect removing the IBS from your year e60. I think it's more of a must-have for more current years.

Deano

After charging the battery overnight I measured 12.85 volts on the battery. With the car running, I get 13.9 volts across the battery. I'm no mechanic, but this let's me assume that the alternator is changing.

By the way, the overnight discharge brings the battery down to 3.8 volts. Batteries plus says they charged my old battery and it's fine, come and get it. I guess I own two batteries now. If I make the trip to the dealer, I imagine they will try to sell me a third.

Thanks for the link!

EuroCarFan

I and a couple other M5 owners had a similar problem and after checking/changing things like the IBS, Comfort Access (CAS) module, door sensors..etc..they narrowed it down to a faulty Telematics Control Unit (TCU) which was keeping the car from going to sleep and draining the battery over night. Some people say one way to check is to turn off the car but maybe sit inside of it and wait to see if you hear noises from modules still staying on. Another way is if the shift indicator light on your shifter is still lit.

Hope you sort things out and that it won't be too costly.

Deano

It seems that the stereo doesn't want to go to sleep. Tonight after turning off the engine, I stayed in the car for about 20 minutes. During this time I could hear a barely audible "dead air" sound coming from the front tweeters. The "on" light from the remote bass volume control stayed on, so I know that all of the amps in the trunk stayed on as well. There was a curious thump sound that happened about two minutes into this. I would describe the sound similar to bouncing a tennis ball off the outside of a door.

I was going to replace the IBS cable, as that comes up as a solution in many forum searches. However now, knowing that the stereo is not going to sleep, maybe the IBS is fine.

Has anyone had these symptoms?

Dean

Deano

Has anyone had their stereo head unit replaced to correct a system that won't sleep and discharges the battery overnight?

545felix

question, where are you tapping the turn on lead for all those amps in the trunk? have you tried disconnecting those to see if the car will then go to sleep?

another thought, the TCU could keep the CCC/amp on if it has failed like the other posters have said. try disconnecting that and see if the car sleeps. you'll get an SOS error, but that goes away once you reconnect it.

rkc88

Hi, I've had sort of the same problem that the cluster lights would not go off but the car was going into sleep mode, after asking on the fourm and following a link I took the ibs off the negative lead and now the light is off and everything is fine. Once I connect again then the cluster lights go back on.

luigi524td

Remaining in the car may prevent it from going to sleep (motion sensor in headliner??). Close and lock your car and look to see if the orange indicator near the shifter and the led lights on the window switches go off. Might take as long as 30 minutes. If they stay on something may be causing a battery drain and it's a process of elimination from there to trace it down.

or_550i

I have a faulty IBS and I removed it a year ago... No issues what so ever. Car will work fine with out it.