I didn't think it's a 100% charge issue it's continue to charge when at 100%. That said, the pre '07 bmw just charged like all cars for the party 100 years but I did notice as mentioned, just getting feedback on the forums, people getting a longer run on their e70 vs. e53.

That said you clearly are In a different class regarding batteries than the regular Joe.

I like being able to check the histogram and never been surprised that the battery is 80% full on average. Unless you are deep cycling the battery is a non issue but I'm a little surprised at how much the car will run off battery when at idle like you noticed.

Good that you posted though; it's far more complicated to diagnose a weak alternator with IBS! Even the bmw repair manual says "it could be this or that". I think you may have discovered the best way to tell: unplug the IBS and monitor realtime voltage!

__________________
2011 E70 • N55 (me)
2012 E70 • N63 (wife)