Hi Jim
Just out of interest really.
Here's some telemetry plots form my Iconic flight last night that was short of the 4000mAh of the batt.
First pic shows how cell 3 gave up first, this is probably where I felt power drop off.
The second pic shows cell 3 against consumption for the whole flight.
What I'm hoping is, that the high ambient, and my lack of any cooling for the battery, are responsible.
With luck and some cooling, I hope to get more out of the batt