Over the last few months had occasional battery failures (dead battery symptoms). Usually occurred when or immediately after son has driven the X5. Figured it was something he did..

This last time, the battery failed to recharge with a 2 amp charger overnight... Hmm.

Pulled the battery and noticed it was a Duralast AGM size H8 with a Dec 2016 date code..This was an expensive battery when new. Kind of surprised it failed so soon.

I replaced it with a FRESH (Nov 2020) Ever Start H8 non-AGM battery from Walmart.
...$129 +12 core..

Back in business.