ORIGINAL: Hammbone
ORIGINAL: rctom
Here's something to think about on this subject.
The Smart Fly power expander and the Spektrum AR9100 use basically the same curcuit for input power, it's 4 diodes that pass current through to the servos while isolating the beatteries from each other.
These diodes introduce a voltage drop. The voltage coming out of the servo connectors is about a half volt lower than what is coming out of the batteries.
While this is not the end of the world, you will find that your system consumes less power with the PE or AR9100 because the voltage to the servos is lower. You will also find your servos to be slightly slower and slightly less powerful than when sending power through a pure copper circuit.
TF
I don't know where you got that info, but it's wrong.
It says right on the Smart Fly website that the voltage you put in is the voltage you get out.
I just checked one of my planes. The voltage direct from the battery was 6.6. I turned the Power Expander on and checked the voltage at one of the servo ports............ 6.6.
I took my spare JR R1222 rx out of the box and plugged a battery into it. Battery voltage was 6.6, voltage at one of the servo ports on the rx was 6.6.
Please don't spread bad info on the forums.
Jim
I have heard the same thing that Tom talks about, but I get the same voltage as you reported. I think you only see this voltage drop if the diodes are flowing current differently, like when one battery in the system fails, shorts, or its voltage drops.
Tom is just repeating what he heard. I bet if you plug a 4.8v battery into one input and a 6v battery into the other you will see this voltage drop that he talks about, because the diodes are sensing the lower voltage and switching to run off of just the 6v battery. It takes a voltage drop on one side to see this - it can't just be an open circuit.