[Pilot-Z]

So I hadn't driven the car in about two weeks. Come out to drive it and when it starts there are messages about the battery being discharged. So I drive it for about an hour. Fire up Bimmer link and it shows the battery at 32%. Drive it another hour and it gets to about 45%. Hook it up overnight to a charger and the charger says fully charged in the morning. Yet Bimmer link shows it's back to 35%.... Drive it all evening out in the country and it never gets above 50% per Bimmer Link. What's the real story here?

[ROASTM]

Originally Posted by Pilot-Z

So I hadn't driven the car in about two weeks. Come out to drive it and when it starts there are messages about the battery being discharged. So I drive it for about an hour. Fire up Bimmer link and it shows the battery at 32%. Drive it another hour and it gets to about 45%. Hook it up overnight to a charger and the charger says fully charged in the morning. Yet Bimmer link shows it's back to 35%.... Drive it all evening out in the country and it never gets above 50% per Bimmer Link. What's the real story here?

I have run into very similar issues as you, as have a couple other friends of mine that have an M2C as well. I don't drive my car much (was ED, put 800 miles on in Europe, and only 1,200 since being back in the states), but it is kept on a trickle charger for at least a day or two if I'm not driving it for at least a week straight. I started getting the "battery discharged, please start engine" notification almost every time I started the car - though never had any actual issues with it not starting back up or driveability/power issues when this notification comes up. Took the car in for it's second oil change (first oil change since the 1,200 break-in service), and mentioned the battery drain issue to the dealer. They ended up testing the battery, and also noticed that one of the battery cables was apparently loose, and said that the battery was good and didn't need to be replaced. This was last week, and have driven the car a couple times since and have not received the message again. That being said, one of my good friends with an M2C daily drives his, but still gets the battery drain message every once in a while, so I really don't know. I also find it hard to believe that a loose battery cable could've been the culprit for me, but who knows? Maybe your battery cable is also loose and that's actually what's causing it. What trickle charge do you use? FWIW, here's the one I purchased a couple years back: https://www.amazon.com/BMW-Advanced-...113381&sr=8-25

[redgs4]

I am running into similar issues. For the moment I just hook the car up to a trickle charger when I'm not driving the car for a few days. I also have a bunch of extra stuff that's drawing on the battery as well [radar, audio]. Next week the audio shop is going to check everything to see if there is an unexpected draw from any of the upgrades. Hopefully this is something as simple as a loose cable or one of the amps not turning off.

I had the M2C in the shop yesterday for an exhaust upgrade and I had them check the battery [100% healthy, 60% charged] and the charging system [everything operational]. I am surprised at the 60% charged as the car was recently driven and sat on the trickle charger a few days prior.

[Pilot-Z]

Thanks guys, car is going in for it's annual oil change in a week so I'll have them test the battery...

[MR RIZK]

Max i have ever seen in BimmerLink is 68% even after a full nights charge