Bingo. I remember discussing the limits with Charles before originally buying them for PP3D. I asked whether I could get away with running 2 x T64s on 8s on a single controller. He said I'd really be pushing the limits of things. Especially when a fully charged lipo cell will pump out 4.25v or thereabouts. I dropped down to 6s for safety sake and have never had an issue with them.

From memory if the LEDs light up when you hook up a battery then it should be fine. If they don't then it's nackered.