[Georgetheowl]

I have decided to look into the battery degradation situation on my 2023 i4 e35 purchased June 2023. The data shows the full charge capacity vs date and odometer.

For most of the charging I have been using the same Lv 2 charger at my company. Most of the outliers are some occational Lv 1 and Lv 3 chargings.

Formula:
Full charge capacity = (energy charged) / (final % SOC - initial % SOC)
All data comes from my BMW app.

Several observations:
1. There is a slight change of full capacity between summer/winter, but at 10% max. When temperature is higher the capacity is regained.
2. Currenly there is no noticable battery degradation when compared to Jan 2024.
3. From the vehicle computer, the calculated full capacity is usually at around 60-65 Kwhr, and sometimes drops to 55 kWhr in winter. Formula is
(kWhr/100 km) * distance of the trip / (SOC at destination - SOC at departure)
4. From OBDII bluetooth reading the battery health is at 93% as of Feb 2025 (more consistent with distance method). Note that this value could be low due to the cold temperature around here (~0 °C at night)

I plan to update every quarter below this post.

[mlanes01]

How do you have data points above 67 on a car that has a 70kwh battery with a useable capacity of 67kwh?

[Georgetheowl]

Originally Posted by mlanes01

How do you have data points above 67 on a car that has a 70kwh battery with a useable capacity of 67kwh?

I report what I get from the app, and I can't argue nor intend to mess with numbers reported by the trip computers.

Maybe the trip computer is metering the power being received at the AC/DC converter rather than the actual power being stored into the battery, so there is 5-20% discrepancy between the two numbers.