If the HP UEFI diagnostics detect a persistent inaccuracy, a calibration will be recommended - this EliteBook 640 G9 does not need it, so it was not presented to me.

In order to check the battery health on HP laptops, you MUST use the UEFI tool as HP hides the actual heath data from the operating system. The tool can be downloaded here and written to a USB drive, or a secondary partition on the laptop - the choice is yours.

Run the HP diagnostics and do the following to access the battery test:

Locate Power in the diagnostics

Click on Battery and select Run once. This will take approx 2-3 minutes.

NOT SHOWN HERE Click on Battery details to review the health data.