A device which can report its battery level can do so in two ways:
Report when the battery is empty or low.
Report the precise battery level that is left.
Give your driver the measure_battery capability if it supports reporting precise battery levels on a certain numeric scale (e.g. 0-100%). Give your driver the alarm_battery capability if it supports alarm notifications when the battery level reaches a certain threshold (e.g. 'battery level less than 10%).
Never give your driver both the measure_battery and the alarm_battery capabilities. This creates duplicate UI components and Flow cards.
Battery devices must specify an energy object with the batteries property. This should be set to an array of strings which represent the batteries in the device. For example, a device with 2 AAA batteries must specify the following energy object: