He uses the RCA wire and terminal for the shielding, and simplicity. If you peel back the outer coating, you will find a shield and outer braid, this is your NEGATIVE wire. Then you will notice yet another insulating layer, and inside that, you will find the POSITIVE wire. Its not much different than Coaxial cable, if you have ever made your own leads at home for TV, VCRS...etc.

Strip them back and solder them to a spare servo HD servo extension, (outer layer to brown or negative, inner wire to red or positive) so you can plug it into a switch. Be sure to keep the wires separate once stripped, and cover them with heat shrink to protect from shorting. I usually use a heavy duty charge jack, similar to the one used for the RX pack, for charging and testing. With Ralph's ignition, I would recommend a 700mah 4.8v pack. There is no need to carry anything larger as it is a pretty efficient ignition system and needs nothing more.