3DR Solo Dual Charger

This project came about thanks to information posted by members of the 3drpilots forum. Information and source for most of the electronics required for this build can be found at Grant Conery's excellent Instructables write-up -- http://www.instructables.com/id/GM-Multi-Solo-Charger/. His multi-charger build is also here - http://www.thingiverse.com/thing:1496497

As I don't go through very many packs when I fly, I went with a dual charger setup. Having a 200 x 200 mm print bed also dictate