Battery discharge during idle time

[PDEric]

I have a '19 M3 AWD with ~38K miles. When sitting idle, I see that sometimes I lose some percentage of charge, but also sometimes gain. The car is sitting in my garage and the idle time varies from a couple of hours to a day. See the energy screen below. Notice there's around a 5% drop in charge at about 38 miles driven. Then there's a couple percentage gain around 68 miles. Is the battery recalibrating when idle or what? Thanks for any thoughts on this.

 

[AlanSubie4Life]

I have a '19 M3 AWD with ~38K miles. When sitting idle, I see that sometimes I lose some percentage of charge, but also sometimes gain. The car is sitting in my garage and the idle time varies from a couple of hours to a day. See the energy screen below. Notice there's around a 5% drop in charge at about 38 miles driven. Then there's a couple percentage gain around 68 miles. Is the battery recalibrating when idle or what? Thanks for any thoughts on this. View attachment 936338

Something like that. No one knows. If you do a search here you’ll find a thread about phantom drain a couple months ago that extensively documented this.

But note the 5% drop is large relative to the normal steps seen so it likely includes some sentry use or just a long period between drives (you’d have to check the Park page and carefully correlate for that - unfortunately they don’t provide the breakdown for each step).

Note that the park page does not include negative losses (gains) so the positive steps you see will not be reflected on the running total on the Park page. At least, with the current software…. So Park page totals cannot be relied upon for the “since last charge” data unless you know there were no positive steps.

But yeah; it’s not uncommon to see a 2-3% drop or gain in 15-30 minutes. Very normal.

 

[zivac87]

Something like that. No one knows. If you do a search here you’ll find a thread about phantom drain a couple months ago that extensively documented this.

But note the 5% drop is large relative to the normal steps seen so it likely includes some sentry use or just a long period between drives (you’d have to check the Park page and carefully correlate for that - unfortunately they don’t provide the breakdown for each step).

Note that the park page does not include negative losses (gains) so the positive steps you see will not be reflected on the running total on the Park page. At least, with the current software…. So Park page totals cannot be relied upon for the “since last charge” data unless you know there were no positive steps.

But yeah; it’s not uncommon to see a 2-3% drop or gain in 15-30 minutes. Very normal.

Park tab has no negative losses but it can lower previous drains. If you had 5% standby drain it can lower it to 4,5%

 

[AlanSubie4Life]

Park tab has no negative losses but it can lower previous drains. If you had 5% standby drain it can lower it to 4,5%

Yes, important to clarify. (Since it is broken and confusing and behaves arbitrarily.)
Not in a separate event I mean. For a given session it can offset.

Since a net gain of energy is reflected as 0, the totals cannot be trusted. Have to look at the driving tab!