Blame the bmw engineers .... they have electronics that with lower voltage gets flaky. It is fact the prior owner of my x5 replaced a battery and didn't know how it needed to be done. Then within months he has a transmission which h he can't take out.of park or like that. Of course he does not think it is voltage and battery he thinks it a transmission problem. I won u 'd have too! But bmw tests transmission and concludes it.is good. Now if they wanted bmw could have raped him for a transmission. But instead they find the wrong type.of battery and I bet he is then somewhat happy to pay only $600.versus for a transmission.
Fact low batteries and wrong introduction can cause flaky stuff. I will be changing the battery carefully and early so I need not experience flaky stuff