Thread: Mini-HowTo How to choose a power system
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Old Sep 14, 2007, 12:37 PM
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Gustafs, Sweden
Joined Feb 2006
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Originally Posted by rjm24
I have a question about the BEC. On my receiver i have a 4 plug ins. Ailerons, Rudder, Elevator and ESC. I have only one battery. Do my servos get power through the ESC? I read this on top but was not completely understanding. I guess my real question is that i have look at many servos on the net and most of them say that they are 4.8 volts. I know that my battery is 11.1. Does my ESC lower the voltage for the receiver? or do i have 11 volt servos and receiver?

Do some planes have 2 batteries one for motor and one for radio?

Your ESC powers the receiver and if you are using high voltage and many servos or just want to be on the safe side you can use another battery to power the receiver. Most servos run on 4.8V and many can run on 6V for extra power and speed.

Most likely you have a ESC with a linear BEC, it take the voltage down to 4.8V and bleeds the excessive voltage off as heat, as you can understand it's inefficient and heat up the ESC. Some little more expensive ESC's use a switching BEC circuit, it switches the current on and off very fast to give a average 4.8V. These ESC's can handle more current and still be able to power servos without getting too hot and shut down. My personal limit is:
Linear max 3S(11.1V) and 3 servos, Switching 3S(11.1V) 5 servos or 4S (14.8V) and 3 servos. For anything above this I use a separate BEC circuit (UBEC) or a Rx (receiver) battery pack.

Hope this helped you.

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Last edited by wolw; Sep 14, 2007 at 02:43 PM.
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