FT-411E Battery Pack

I have not printed yet the v82, but it contains fix for issues found in the previous revision.

The supports are a bit painfull to remove, it may be better to print with a soluble filament for supports but I have only one filament.

Better printed in black, and, may be possible to be paint to "hide" supports removable white spots.

It can't fit three 18650 but it may fit three 16650.
I will probably use a standard li-ion battery with a pcb-addon to charge from usb and a boost to get ~7V from output (2.5W, 12V for 5W TX)

Various notes or not fixed (yet?):
- the door may need a little sanding to fit properly on one left or right side. maybe 0.3mm less on width

Battery pack v82 fixes:
- wall with ends too fragile (the one right before the hole for the "push to remove" button)
- holes of