Test setup
As a test, I stored a new BQ983 battery outside the Stromer at 18 - 22 °C. The capacity was calculated using the measured voltage (unloaded) at the output of the CR245 charger and based on a standard charging curve U/% for Li-ion batteries.
Compared with the Omni reading, there was a deviation of around 8-10 %, which is why I only started the measurement at 89 %. The measurement period was 21 months.
Even if the individual measuring points do not correspond with the 100%-ig omni display, a clear statement can be made.
The self-discharge rate is approx. 1 % per week or 4 % per month.
Self-discharge in general
Current data on the so-called self-discharge of Li-ion batteries (not individual cells) is 3 - 4 % per month at room temperature, depending on the BMS. This is almost identical to my test above.
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