Hello All,
Like what has been mentioned earlier about batteries and would like to add my experience and experiment.
I have a Lanier Yak-54 87" with a 3W-75i.
Engine has it own switch and battery.
Wing servos, four Hitec 645mg
Elevator, two Hitec 645mg
Rudder, one Hitec 5755mg
Receiver JR 9ch PCM
Switch harness, JR heavy duty
Battery, Hangtime Hobbies 2300Mah A123 dual line EC3 and heavy duty JR (only JR end used in this first set up)
Voltmagic battery monitor and logger.
I flew this airplane a long time. The voltmagic never logged a voltage drop even when working the servos hard back and fourth.
Then I decided to purchase a 2.4Ghz radio set up. I decided to try it in this airplane. The only thing I did was swap out the receivers. While doing pre-check outs so far I noticed no problems. I proceeded to work the servos by doing the hard back and fourth test for a couple of seconds simulating high current draw. Bam voltmagic logged a voltage drop. Crude. I verified the battey was full charge (also tested the battery on a Power Lab 8 charger, tested OK) and tried the test again. Voltmagic logged another voltage drop at the receiver.
I happen to have one of Hangtimes heavy duty switch harness. The one that has dual in (EC3 and heavy duty JR) and dual out (two heavy duty JR). The only thing changed was the swap from the JR heavy duty switch harness to the Hangtimes hobby switch harness (Electro Dynamics). Voltmagic has never logged another voltage drop after the swap even while doing the test.
With the tools that I have I can only theorize that the 2.4Ghz received allow the servos to work harder (for some reason beyond me) and the limiting factor then became the switch harness for the amperage draw.
What I learned is to test voltage drop at the receiver.