After a full day driving with new battery, measured the voltage again.
when engine off/on

New battery:
12.7v/14.1v

Comparing old battery replaced:
12.36v/14.8v

It appears when battery ages, the battery capacity drops with voltage decreasing and the car adaptively increases the charging voltage to compensate that; If the holding voltage dropped to certain level, it doesn't meet the minimum requirement of some component, computer can throw errors, P0890 for our E70.

If the new battery is not registered after installed, it will be charged at high voltage than necessary and could shorten the life? It seems important to register battery to reset those charging adaptation values.

I am sure not professional in battery, just throw some thoughts here.

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2012 X5 35i: Hitch installed; Coded;