With the Monocoupe (10s1p 5000mah) and the Toledo Special (5s1p 5000mah) being some of my favorite planes, I had a problem charging batteries at the field. (EDIT: And now the B-17 with (4 x) 4s1p2200mah)

My experience from last season showed me that I could charge the 10s1p pack 3 times from a 55ah car battery before the charger would show low voltage. So, assuming I didn't fly anything else, I could fly the Monocoupe 4 times in one day and end up with a completely dead car battery, which is not good.

My charging station is located in the bed mounted tool box in my truck. It consists of the following:

(2) 125AH deep cycle batteries
(2) plastic battery boxes
(4) 3/8" copper wire lugs
(2) 1/4" copper wire lugs
(1) 40amp giant blade fuse and holder
Roughly 6 feet of streetwires 4awg wire
(1) 15A deep cycle charger
(1) Sunpro 8-18v volt meter from Autozone.
(1) Toggle switch from Autozone. (Used to switch the volt meter on and off).
Misc scrap wood and other nuts, bolts, and small crimp on connectors.

Except for the couple items from Autozone, everything came from Walmart. The entire project ran me just under $300 for everything.

First trip to the field I charged 5s5000mah x2 and 3s2200mah x6. Second time out I charged 5s5000mah x3, 4s3300 x3, 3s2200mah x6 and 2s2200mah x1. Third time out was today and I charged 5s5000mah x4.

The lowest I have seen it was the end of the second day out where it was 12.4v and the charger claimed 70%...Continue Reading