Battery level MAC command

Hi friends,
my 4200 responds for battery status LoRa MAC command question DevStatusReq with value 255 (DevStatusAns), means “end device is not able to measure the battery level”.

Is battery level measurement implemented in the LoRa stack? Should I set something at 4200 ? How to do it ?

RAK4200 is a module, there is no real electric value to be collected.

And depending on the network, it may not be implemented - TTN v2 for instance doesn’t.