I've been troubled with the battery drain problem in my 04 530i for the past week. I want to fix the problem myself instead of bring the car to the dealership.

So here's how it all happen. I lived in Los angeles California and I drove up north last sunday to spend the holiday with my family. I drove about 200 miles and stopped at a gas station to fill up. when I was done and before i started the car, i turn the key on the ignition to on position and the display showed that the battery has low charge, but i was able to start up the car. I made it home and the next morning i went out to start my car, but the battery was completely flat. The battery in this car is located in the trunk. when i accessed to the battery I saw it sitting on 3-4 inches of water(maybe about a liter). I don't know how long the water had been there. but i would assumed that it is very recent, since it had been raining pretty hard over here for the last two week. anyways, i took out the battery, have someone tested and it was good. the battery is only 6 months old. So i drained the water and fitted a fully charged battery. the very next day, same thing happened. So i had it jump start and drive around for a while. but the battery seems like it is draining very fast. even after a few hours, it has a hard time starting. especially when it is really cold, the battery died after just 3 or 4 hours.

I am not sure if there's something wrong with the charging system or some faulty sensor that causing this high battery drain.

i have been reading on the forums and it seems like this is a quite common problem. however, many cases are unique. i know there's a lot of smart people over here, i would really appreciate if you can answer some of my questions.

how to i perform a parasitic test? they said the car might not go into sleep mode after 20 minutes and causing this drain. I am not sure where is the LED light to look for as a sign of the car going to full sleep when that thing is off. Because i found a lot of led lights inside the car.

Do you guys think that the water in the battery compartment might have damaged the IBS sensor?

does the 04 model has the comfort access? some said the drain is caused by the faulty sensor of the comfort access by the door. but i don't think my car unlock with just the key in my pocket, plus i don't have keyless start.

i also read that a lot of you have the message on idrive saying "high battery drain" that never occur to me, does the 04 model have this message on the idrive.

how long does it take to fully charge the battery when driving. knowing this i can test the voltage on the battery to see if the charging system is working correctly.

sorry for these many questions. i really don't want to take my car to the dealership and have them rip me off since my car is no longer under warranty. plus the closest dealership from my town is 60 miles!

I don't know much on battery discharge problems but did u check to see if the modules in the spare wheel well got wet? Pull out your spare and check.

Quite possibly. Check your Micro Power Module.

MPM Failure

If there is any hint of water down where a spare tire should be in the trunk, suspect the MPM. The dealer will try and get 1k outta you to replace the wiring harness, module, and associated couplers, ties, etc. Kindly thank them with a "no", walk over to the parts counter, and buy the damned thing (shouldn't be more than a couple hundred). It MAY need programming.

After you've investigated and eliminated the water problem test the alternator output by using a VOM and the indicated voltage at the battery when the engine is running. If the charging voltage is less than 12.5V the alternator may be a problem. Even a new fully charged battery will fail quickly w/o being recharged. I don't know how many hours of driving might be required to bring a dead battery to full voltage. A 'regular' charger might take 1-3 hours / a trickle charger 6-8+ hours. If your modules are wet you may be able to save them. There is a bulletin that described how to relocate them to prevent future occurrences. As far as a replacement DIY ... on the surface it may be cheaper to buy and replace a module - IF - a big IF you get the right one ID'ed and replaced. Otherwise you might be buying several parts until the right one is replaced.

Good luck with the water damage - if it gets real expensive have you considered filing a comprehensive insurance claim?

So I check my car this morning after letting it sit over night, I used a multimeter and the battery showed a 3.4v. I then jumped the car and check it again with the engine running on a empty battery. It showed 12.8v I took the car on the highway for an hour and check it again with the car running and without. With the car running I got it slightly over 14v with the engine off it reads a little over 13v.

From this can I conclude that the alternator as well as the charging system are functioning properly. And the battery also hold its charge as it should? And if this is true, then I have an excessive draw after I turn off the car which causing the battery to drain or the car does not go to sleep after I turn it off?

I also unplugged the IBS from the negative cable, if this is the faulty sensor that is causing the leak, then my battery should hold it's charge tomorrow. I will keep updating the result here. I hope I can narrow down the problem and maybe even fixing it. Any more input will appreciated, this post can also be a reference for others in the future, but let's hope nothing will happen to your e60

I check under the spare, there's a little bit of water at the bottom and some water mark around the MPM unit, but I don't think it got Inside the module. I opened up the casing and it looks good, no sign water, burn or fried smell whatsoever. But I do need to relocate it and I recommend this to everyone else. This is a very bad design from BMW, I don't know what they were thinking!
I just tested again after letting it sit for an hour. This is with the alarm on, window disabled LED on, and IBS disconnected from the negative cable. It reads 12.9v, there's a little drop but I assumed this is normal. Let's hope the cause is the IBS. The LED light did went off when I checked it an hour later so this means the car does go into full sleep, right?
Anyways, you guys been very helpful, I'll keep posting.

In regards to the water leak in the battery compartment, I conducted a water test and found a small leak coming from a bad seal from rear window on the bottom right corner which allows small drips of water into the battery compartment. I used a razor blade to clean off sone excessive old seal and put some clear silicon around it. Then I took it for a drive in the rain for a drive and it looks like the problem is solved. :)

could u post a picture of the exact spot?

Pls let us know the exact spot of the Ibs sensors. Can u capture in on pictures. I want to disconnect the Ibs sensor from my battery but I don't know where is it. Is there a nut that we need to remove first b4 we can disconnect the Ibs sensor? Pls help.

you could always buy my battery i have the heavy duty one for sale https://5series.net/forums/public/st...t/thumbsup.gif