What is the difference between adding two drone batteries in series vs a parallel connection for flying the drone?
$\begingroup$ Do you mean for charging purposes or like connected together on a drone? $\endgroup$– ifconfig ♦Apr 18, 2020 at 23:51
$\begingroup$ I mean connecting them to use on a drone. $\endgroup$– Jacob B ♦Apr 18, 2020 at 23:54
Batteries in series = add the voltages, ie two 3S 1300 30C packs becomes 6s 1300 30C.
Batteries in parallel = add the capacities, as above you get 3S 2600 60C.
There's no particular pros or cons for either, many larger commercial drones use combinations of packs in series and parallel to get the power source they need.
For smaller quads though the overhead you get in extra weight from the leads, connectors and wiring is greater so it's generally less practical.
As is the case with all other kinds of batteries (voltage sources in general), connecting batteries in parallel increases the maximum current which can be supplied to the motors and a series connection increases the voltage supplied to the motors.
I wouldn't recommend creating either circuit on a drone with individual battery packs on a 5" class or similar quad.
$\begingroup$ Putting batteries in series is quite common for some of the smaller micro-drones to be able to fly them 1S for indoors and 2S for outdoors. Take the Mobula7 for example to fly indoors you use a single 1S battery with a jumper on the other battery plug, and outdoors you fly with two packs in series. $\endgroup$ Apr 19, 2020 at 0:27
$\begingroup$ Oh, I didn't realize that. I was talking about not combining two large 5" class batteries on one quad. $\endgroup$– ifconfig ♦Apr 19, 2020 at 0:32