I have used a very small single pole double throw switch like in the pics. I attach 3 leads to it - female plug for battery, male plug for Rx, and another male plug for charging. For wiring, I just attach all the negative leads together. The positive battery plug lead gets soldered to the centre post of the switch, the positive Rx lead goes on one of the outside posts and the positive charge lead goes to the other outside post. I put heatshrink over the leads before soldering, then shrink it over the solder joint.