I bought a cheap radio for a trainer project and quickly figured out it was going to be a bummer keeping 8AA batteries in it all the time. I do have a bunch of 3S lipos that aren't tip top anymore... Time to do a little hacking.
Four screws to take off the back of the transmitter
Unplug this connector.
Clip the other ends of the two wires from the battery clips and cutout the battery tray to fit your lipo.
I use these connectors for my lights so that I can run the lights off of the balance tap. I'll do the same thing here. Just run the transmitter off of the balance tap. I get 'em from HobbyKing but I'm sure you can find them other places too.
I just cut the other end off and slip the two middle pins, leaving the red and black outer pins.
And splice to the original power wire.
Had some old foam laying around. Placed it inside to keep the battery from getting scraped up against the circuit board.
All Connected up
Ready to rock, no more pesky AA batteries.
A couple of quick notes.
I disabled the charging port on the transmitter. No biggie because I'll be charging with my regular battery charger. I believe there are also 3s packs that are specific to transmitters that could be used w/o having to cut the battery tray.
This mod will very likely void your radio's warranty. If you decide to do it for yourself proceed at your own risk.
Check out this excellent video from lonewolf7717 He did a couple of things differently than I did. Awesome work and I kind of wish I had seen it before I did the conversion. Thanks Lonewolf for letting me link to your video!