Good to bring this point up re: servos stopping at higher voltages than receivers. And a nice catch on the LiIon vs. LiPo ... most of us would not check that unless we used a computer-driven device to plot the discharge curves of our batteries.

The problem with servo drop-out was first noted here on RCU six or so months ago when the junior achievement technical team at JR/Horizon posted a video supposedly showing a Futaba RX stopping working at low voltage. I went looking for the thread so I could link it here but could not find it. I sure hope I recall it correctly... did someone else see it too?

The thread pointed out that if you watch the video closely, the servo (it was a JR of course) stopped responding to stick movements on the TX as the voltage to the Futaba RX (a 607 or 617 as I recall) was lowered ... BUT ... the green light was still on ... the RX was still working. Duh.

I got curious and checked a bunch of Futaba and JR digitals I had in the shop and it was pretty much the same for all .. they stopped close to (but below) 4V and the RX held on much lower.

So, Jack is doing us all a great service in his thorough troubleshooting to remind us if a critical system failure point. And many thanks to the JR/Horizon team for unintentionally bringing attention to the matter in a failed attempt to make a "gotcha video". Perhaps they should hire more engineers and fewer ad copy writers :-)

Dave