Changes
/* Batteries */
* https://www.reddit.com/r/Multicopter/wiki/power
* C rating : the higher, the higher current you can draw http://www.rcheliwiki.com/C_rating
* S is the number of cells, and is representing the tension (1S=3.7V, 2S=7.4, 3S=11.1V, ...)
* Balancing: Cells need to be a the same charge level so we can avoid overcharging.
** It's a good idea to always use the balance mode to charge a multiple cells battery
