After shutting down the Heltec V3 via the app or holding down the power button for around 10 seconds I am measuring a current draw of about 2 mA. I am assuming this is light sleep mode.
Is there a way to put the module into deep sleep mode which according to the data sheet is 10 uA?
This 2mA may be the power LED (plus some LDO) if you power it over USB. Did you test when powering over the battery connector only?
The shutdown is using the deep sleep mode indeed.
Yes I am measuring the battery current with a Harbor Freight multimeter
Let me find my Fluke and do some more investigating.
You can also flash this deep sleep example and do your measurements to see what the heltec is capable: