Transmitter Batteries
One more thing to add, I have been running dry cells (1.5V) in my transmitter. This is a holdover from my pre-Spektrum days when I needed the very max transmitter wattage to combat glitching. A 24-pack of E2 is $10.88 at Sam's Club and they last at least a couple months. I keep them in the high 11 to 12 volt range for big races, otherwise let them get down as low as possible for practice - just be sure to put in fresh for big races. Not as cheap as rechargeables - I probably just need to order the $6.99 spektrum cap - but these were accessible same day vs. having to order and I guess I'm lazy too. I consider this pretty cheap insurance against the 1 glitch that might cost me a race (and parts).