I am using a 4400mah LIPO saddle pack from them that has worked perfectly so far. I have had this pack for about a month and a half and use it exclusively, twice a week, for all qualifiers and the main. I charge it in between heats and have had no problems at all. The pack doesn't even get warm and I am using a Novak GTB 5.5r. Our heats and main are each 5 minutes long.