Windows does not shut down if battery is already below critical level

Question

I am validating a custom UPS battery driver. It is based on https://learn.microsoft.com/en-us/samples/microsoft/windows-driver-samples/simbatt-simulated-battery-driver-sample/

On both Windows 10 and 11, if the driver initially reports a capacity below the critical level (in the power options) then Windows does not automatically shut down. It does trigger the Critical battery notification.

Trying to understand if this behaviour is discussed anywhere.

Seems the battery driver needs to "fake" some good capacity readings, before sending the real "critical" battery capacity.

Answer 1

Dear Mark

Yes, based on your description and the linked Microsoft Q&A thread, it appears that Windows does not automatically shut down if a battery driver initially reports a capacity below the critical level.

Instead, it seems to trigger the Critical battery notification but not the shutdown action. This behavior suggests that Windows expects to see a transition from a non-critical state to a critical state to initiate the shutdown sequence.

Therefore, your observation that the battery driver needs to "fake" some good capacity readings before sending the real "critical" battery capacity is a valid conclusion given this apparent Windows behavior.

Best Regards,