I have a 2100 NiMh pack from Batteries America, have never been able to kill it in one day yet. Capacity is starting to drop now so will need a new one soon. I had six or seven Planes programmed on my 9c as soon as I got it so i needed something good. I may only have the one Tx with me so it covers all my flying and the stoch pack just doesn't cut it on a long day. Plus it will last several shorter days.