How to leave the battery while going in hollidays

[alohart]

I have left my '18 BEV94 several times for 8 weeks in the UK winter. I have never disconnected the HV. I leave the car at around 70% initially and disable the internal alarm by the second press method.

Monitoring the car via the BMW app during these periods suggests that the 12V is periodically topped up at the % HV level does decrease a few %s.

I've experienced this automatic 12V battery charging on our former 2019 i3, but I haven't found any documentation of this feature that explains how it works and when it might not work. If the 12V battery fails during storage which has happened to several i3 owners, would automatic 12V battery charging continue over and over until the HV battery is fully discharged? Not knowing persuades me to play it safe and just disconnect the 12V battery.