2008 535xi recurring electrical death

[mattmadden_tf]

I'll try to keep this short and conscise. I've had the car for about 2 years, bought it off my boss who dumped a ton of money into it before deciding he'd rather sell than let his son drive it.

Early 2022, had a full array of lights and warnings go off after sitting at the airport for 3 days, had a new battery installed and registered, this shop is now out of business.

November this year, driving to the airport and I get a huge freak out, overheating, all the warnings, gauges freaking out. I limped the car the short distance home, where the next day it was stone electrically dead. I did some research and landed on the alternator so I replaced that myself. Still would not start, determined that the battery was shot. Came to the conclusion that the dying alternator nuked my battery. Since the shop that installed it is dead, i had it warrantied at Midas (Interstate battery). Car worked fine for 2 days. This morning I hear the alarm going off, and discover I once again have a completely dead car. The replacement battery has not been registered to the car.

I have not had the battery tested again, but any suggestions on what i could be missing? Any common places on these cars to look for a draw? I've tried to do some research but not even really sure what to type in to start looking.

I did discover the battery cable recall in my research tonight, if I call my local dealer will they be able to tell by the VIN if this car had that done?

Im moving from SoCal to Indiana in 2 weeks and I decided I want to keep the car, but damn this thing can be frustrating.

Thanks!

[mattmadden_tf]

Update: the battery cable was replaced under recall June 2012

[Machinecz]

I proceed by first attempting to disconnect the hood alarm sensor. My next step involves disconnecting the front section, thus eliminating the alternator, starter, or GPM in the diesel version. Subsequently, using ISTA, I will monitor the excitation, which often might be caused by the trunk switch or a faulty comfort access handle. Of course, there are many other possibilities, such as water ingress to the engine unit or trunk, leading to random activation and discharge. That would be a further step. Good luck.

[mattmadden_tf]

Originally Posted by Machinecz

I proceed by first attempting to disconnect the hood alarm sensor. My next step involves disconnecting the front section, thus eliminating the alternator, starter, or GPM in the diesel version. Subsequently, using ISTA, I will monitor the excitation, which often might be caused by the trunk switch or a faulty comfort access handle. Of course, there are many other possibilities, such as water ingress to the engine unit or trunk, leading to random activation and discharge. That would be a further step. Good luck.

Thank you! Cars getting loaded on a trailer to head east soon but I will take your advice

[sloweste9x]

What ended up being the issue?