There is an article in Extreme RC mag about Lipos in general are not recommended until the radio gear lines up without a regulator. I read the article, didnt think too much of it and guess what???? with about 26 min into a 30 min main. Wholla!! Heats up and shuts down. I bought a NIMH on sunday. Article makes sense. I know some of you have not had a problem, but it is a matter of time. It will happen. I was the same way. Kickin myself in the A$$ right now. lol