Anyone ever done this?

[squeeforever]

Maybe adding a capacitor to the third channel will help?

[BrianG]

I don't see why it wouldn't work. Your typical 5 cell receiver pack is supposed to be 6v, but it's actually closer to 7v at a full charge. That said, isn't a Lipo over 4v per cell at full charge? That would make it over 8v total. I personally wouldn't go quite that high. Even if nothing blows right away, there may some components (mainly capacitors and ICs) that may be stressed and blow sooner. The added voltage will give servos more power and stress their driver circuits a bit more.

If anything, a capacitor will help keep the voltage up during brief relatively heavy current draws, but won't reduce the voltage at all. You could use a small linear regulator since the voltage difference is low, but there still might be a bit of heat depending how much current your servos pull.