Is there a sneaky way to get active battery milliamps ?

Hi,

I'm afraid not - there's no easy way to find out as there is no built-in current measurement functionality. I guess the best you could do is look at the battery voltage, as there may be some internal resistance in the battery - lower voltage = more current draw.

Turning everything off, measuring voltage, turning it on and measuring, and finally measuring again with it off might give you more helpful information.

For development I actually opened up a Bangle, disconnected the battery and brought it out to a connector. Then I use http://www.espruino.com/Power+Meter - but obviously that is a bit extreme.

Potentially if you had an app (maybe modify the GPS Config app?) that allowed me to easily change GPS modes then I could try one or two here and see what the power usage was?