eNate wrote: ↑Thu Jun 23, 2022 8:11 am
I always thought the HV disconnect was recommended but not required. I had no idea it could result in this much chaos.
BMW's TIS documentation indicates that with early integration levels (system software versions), if the HV disconnect isn't disconnected prior to disconnecting or externally charging the 12 V battery, problems could occur. It also states that the HV disconnect shouldn't be disconnected until the HV system goes to sleep on its own, which could be as long as 30 minutes after any action that would keep the HV system on like unlocking/locking/opening/closing doors, the hatch, or the frunk. The documentation states that these problems were fixed in an integration level update which occurred during the 2014 model year.
Even though our 2014 i3 was delivered with an integration level that should have protected against problems that might occur when the HV disconnect isn't disconnected before disconnecting or charging the 12 V battery, I was always careful to disconnect the HV disconnect after the HV system shut down on its own and only then would I disconnect or charge the 12 V battery. I stored our 2014 i3 for 3 to 9 months every year except 2020 and never had any problems. I just stored our 2019 using the same procedure and don't expect any problems.
Based on reports I've read about problems other i3 owners have had when changing their 12 V batteries, I'm convinced that not disconnecting the HV system or not charging a new 12 V battery fully before installing it can lead to problems that could be difficult to fix.
[22-04-25 to now] 2019 BMW i3 Imperial Blue Metallic, Giga World, Tech + Driving Assist, Heat Pump, 428 Wheels
[14-11-05 to 22-06-15] 2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging