How are battery health percentages determined?

The battery itself maintains some critical values which macOS reads from the battery. macOS does some manipulation of this raw battery data since if you do the math from the raw data the macOS values are off by 2% to 5%....some of the deviation varies when it is at 100% and near 0%. I have no idea why Apple does has this deviation. The battery raw data includes the Full Charge Capacity and Design Capacity along with the Current Capacity values (all report in mAh). Simple math from these raw values gives you the current charge level and what macOS calls "Max Capacity".

Charge level (%, what is displayed on the menubar) = (Current Capacity / Full Charge Capacity) * 100

Max Capacity (%) = (Full Charge Capacity / Design Capacity ) * 100

The third party app Coconut Battery provides a bit more battery information and provides a history of monitored battery values.

No Apple employees are participating in these communities, and we fellow users are not permitted to speculate about how the macOS product team may or may not have implemented battery health calculations in the operating system.

PavloUkraintsev wrote:

Do you know how to write a letter for Apple ?

Corporate Address

Apple

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