Other suggestions I have seen on the web include, replacing the Comfort access module, upgrading the vehicle software, replacing the master computer replacing the IBS (intelligent battery sensor), and replacing the foot well control module.
but that has not fully solved the problem. BMW quickly diagnosed that the car was not "hibernating" properly and determine to replace the handles. I have seen many threads on this site addressing this issue, but I have not seen a post that addresses this problem conclusively.
I feel as though the problem has been improved, but still exists and I am a day or so away from a completely dead battery. Moreover, the car starts very hard - several slow cranks before firing. I received a P Brake Fault, and a Power Window Fault. Yet, within a day or so the vehicle had noticeable power issues again. BMW has since diagnosed the problem as an issue with my Comfort Access, and they have replaced the "handles". I recently had a dead battery in my 2006 750, replaced it, and within hours the brand new battery was completely dead. I'm not sure if 2008 MY and up has an orange indicator or not - just check during the evening to see.ΔΆ006 BMW 750Li Power Drain Issues and Comfort Access It will go off (or dark) after 16 minutes after you turn the car off and exit the vehicle. A good indicator of whether a 5er is going into sleep for 2007 MY and earlier, is to observe the orange LED on the shifter console. I've attached a photo of my Fluke multi-meter showing a draw of 27mA while my X5 was "sleeping". You do not need to lock the car for it to enter "Sleep Mode" and there is nothing that you have to do - it usually happens about 16 minutes after you shut the engine off and leave the vehicle with radio off, etc. "Sleep Mode" is a state of rest of your BMW's electronics when there is less than 38-50mA draw at "rest", usually after about 16 minutes. OK, I've done quite a bit of troubleshooting of various electrical problems with our 2002 X5 - I'm no expert, but here's an explanation in a nutshell. I think the fact that I had not started the car in a few weeks also contributed to the partial draining of the battery. I have since removed the USB stick when the car is not being driven. This is also NOT discussed in the manual. Clearly the USB device was active when the car was not. I always keep a USB stick plugged into the USB port and I just noticed that the little green LED on the USB stick that indicates read/write activity was flickering on/off even when the car was parked, idle, and the ignition key NOT inserted.
It is possible my car was not going into full sleep mode, but I can't be sure. I had to put the car on a battery tender overnight to bring the battery back to full charge. While my battery never drained to the critical level that the car wouldn't start, it was exhibiting strange symptoms - date/time needing to be reset, avg mpg readings lost, radio dropping out when the engine was starting - all symptoms of a weak battery. I have a thread going related to this issue:
Anyway, I hope this helps in explaining "sleep mode" and I can provide specifics in how to connect a (high-end) multi-meter to test for total system draw during "sleep" if you'd like. So, keep this in mind when installing aftermarket electronics yourself or "professionally". These items can certainly cause a greater than 50mA draw and your 5er will never enter sleep mode - your battery performance will suffer greatly - in other words, your battery will be toast within a month or so. Things like aftermarket car starters, and devices that are hard-wired incorrectly into circuits that do not shut off with the ignition "key" and/or start/stop button. Now that I've described sleep mode, keep in mind there are a few factors that can prevent your car from entering "sleep mode" - specifically, anything that can cause your 5er to ever exceed 38-50mA draw at rest. I'm not sure if 2008 MY and up has an orange indicator or not - just check during the evening to see.
Click to expand.OK, I've done quite a bit of troubleshooting of various electrical problems with our 2002 X5 - I'm no expert, but here's an explanation in a nutshell.