I have a 2010 535i. If I leave it sit for a week I will get the low battery notice when I start it up. I replaced the old battery a year ago. To date I have trickle charge the battery when we don't use the car.

Yesterday, I once again charged the battery. Last night ater sitting for a few hours it read 12.6 volts. This morning it now reads 12.5 volts. If I let it sit for a few days it will be down to 12.4-12.3 volts. This tells me there is a slow discharge somewhere.

This morning I was looking at the IBS and noticed another wire spliced into it where it attaches to the positive battery teminal. It doesn't look factory to me. Tracing it up it leads to a fuse and then dissapears into the wheel well. Can anyone confirm if this is actually factory?

I unplugged the fuse and will charge the battery again. After that I'll let it sit for 24 hours and see what reading I get. I'm hoping this is the actual current drain and at this point I have no idea what this wire does. Any input is appreciated.

 

Hi

This is NOT factory ! , try an follow the wire's and se where they lead to , I gess something "aftermarked" stuff , like a Bluetooth divice for Phone etc.

 

That wire is factory on my 2010 528i

 

My 2008 550i will do the same thing if I don't drive it for a long period of time. It actually kind of bugs me a bit. It just doesn't look right to me when you go to your garage and see your bimmer hook up to a trickle charger.

 

It's now been 48 hours since I disconnected the unknown wire and the battery is still at 12.6 volts. The car is going to sit for another 12 days until I need it again. Based on what I've seen so far I may have found my amperage leak.

 

I just checked the battery after I let it sit for a couple weeks. It's at 12.4 volts so I think the mystery wire was the source of my power drain. Glad it was an easy fix.