I thought about doing the same thing, but most people on here told me it wasn't worth it. You can do 6 volt no problem, you could even put 5 2400mah energizer AA's together if you knew what you were doing. I did it with my rc truck, but don't trust my soldering to the risk of it being in an airplane. There are high capacity nicd & nimh tx packs out there for much less than a lipo.