One of the great things about AnkhMaway beacons is that they provide the battery level in the advertising data. This allows you to view or easily programatically determine the battery level without connecting. For example, here’s the output from the Android iBeaconDetector app:
The last two useful hex characters of the advertising data, ‘5E’ in this case, gives the level out of 100. You can use an online Hex to decimal converter to see the value in decimal that’s 94% in this case.
Note that the battery level in the advertising data is only present for recent firmware versions which might not be the case if you haven’t purchased the beacons from BeaconZone.