[Meg]

My C-HR is 9 months old with 2000 miles on clock. After one week in garage would not start.
AA called and got it going. Service engineer says I must purchase a battery charger/ maintainer and to leave car unlocked as alarm drains battery. This, to me is ludicrous advice! What's the answer?

 

[zx10guy]

There was another member that seems to be reporting similar battery related issues. It appears when the car is "off", that there is still some power draw by some of the electronics in the car.

Later model BMWs are well known to keep pulling significant power from the battery with the car shut off. The fix is if the car is going to sit for a while to put it on a trickle charger/battery tender or to remove the negative battery cable.

I know it seems ludicrous to you but it looks to me that you'll have to either get a battery tender or remove the negative battery cable.

 

[DrZeus]

I was surprised when my 2018 sat for 4 maybe 5 days and killed the battery. 37,000 miles. Mind you, it will be 3 years old in July so it's not too much of a stretch for battery life as far as averages go but, my previous vehicles lasted longer.