RE: NiMH Rx batteries
Hi,
I used brand "X" NiMH cells of 350 mAh and that worked well with 3 servos.
The only thing you have with NiMH cells is that the voltage drops quite a lot when you draw very large currents. For exemple when you use them as power pack for your e-drive. It is unlikely this will happen when using them in an RX-pack.
If you don't trust it, measure the voltage with 1 or more stalling servos. This is a good indication for the condition of your battery pack.