X20/X20S and Ethos v1.0.11 User Manual
Configure the Consumption sensor to use 'mAh' units, and set the range to suit your Lipo.
Select the source as 'Current2.4g'.
Add a new Logical Switch using the Delta (d>X) function to monitor the Consumption
sensor, and become True/Active every time the consumption reaches say 200mAh, or a
convenient fraction of the battery capacity.
Add a Special Function to speak the total value of 'Consumption', i.e. the total mAh
consumed, every time 200mAh has been consumed.