Calculation of battery degradation BMW i3 94Ah

Bert Duursma

ABRP indicates that degradation of my BMW i3 battery would be 12%. However the nett capacity according BMW for a new battery would be 27.2 kWh. In a hidden menu in the car the current capacity can be retrieved. Currently this value is 27.5 kWh. So slightly more than the (careful) indication of BMW. This is the situation with most BMW i3's. So no degradation at all.
As ABRP always is upto 20% too pessimistic with regard to SoC at arrival, I wonder if that has to do with the calculation of nett capacity of the battery. If ABRP uses the BMW value of 27.2 kWh and then deduct the 12% degradation, the outcome would be a nett capacity of 23,9 kWh instead of the actual capacity of 27,5 kWh.
Question, how is the 12% degradation determined?

An example. This morning I had to go to a place 23km from where I live. Battery was charged at 100%, ABRP predicted a SoC of 81% at arrival. In reality the SoC at arrival was 89%. On my way back the same situation:
SoC at departure 89%, predicted SoC was 71%. At arrival battery SoC was 78%.

The problem with this is when doing trips of over 150km, ABRP suggest to charge the battery way too early.


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José Ignacio Martín Jiménez

Same problem with i3 120Ah. It seems that ABRP uses the net capacity published by BMW and degradation from Electrified to compute remaining capacity. But Electrified uses 40 kWh as net capacity to calculate degradation. See attached image below. Left column rounded in blue is kWh from hidden menu (that is correct). Right rounded column is degradation calculated by Electrified.



Status changed to: Closed



You can turn of the automatic setting for battery degradation now (it will not be turned on again in CarPlay, as it used to) so you can at least circumvent the problem.



The i3 OBD PIDs were decoded by a community effort, I've posted on the thread on our forums asking for some help investigating, as we don't have access to an i3 to investigate directly ourselves:



Status changed to: Investigate