Consistently charging over limit on my TWC?

[mapman]

Recently I’ve noticed that despite the charge limit being set to 70% in my M3LR the car is routinely at 74% when I set out. This is a new behavior after having the car for the better part of 2 years.

(I use that limit consistently except for road trips, when I schedule the car to go to 100% at departure time.)

Nothing has changed with my TWC setup.

Is this likely a spring temperature-related thing? Something in 2024.3.15?

 

[shingles]

It's fine and it's pretty common. I am not smart enough to know all the chemistry that's happening and the math behind the BMS... but your charger IS stopping at set percentage... but after it settles a while... it can go up or it can go down.

 

[Sophias_dad]

Its battery temperature related, and you have probably only just started noticing it.

 

[jmaddr]

Yep, usually temperature fluctuations. When you finish charging the battery is warmer and then when you get back in the car several hours later, it's cooler. BMS (battery management system) estimation is more of an art than calculated science (though that's all it really is).

 

[mapman]

Figures. Thanks, folks.