DCRC

My Robotics teacher is wondering if he can hook up 2 esc's with bec to one 4ch futaba reciver??
Will ths fry his reciver because of the extra voltage?? any input appreciated!!

smokingcrater

no, it usually works fine. it won't double the voltage, they are in parallel. what usually happens is that the one that is operating at a slightly higher voltage supplies the current, while the other one does basically nothing.

what you can do in this situation is power them both off the battery, but cut the power and ground lines on one of the esc->rx wires. (this is how us micro heli fliers do it all the time, since we have both a main esc and tail esc)

if you want a diagram head on over to here... if you look carefully the main (brushless esc) powers the rx and the gyro, while the tail esc doesn't have to power anything.

http://www.helihobby.com/commonImages/l_sepImage3.jpg

Bax

My Feedback: (11)

If you operate two electronic speed controls from one receiver, use one of the speed controls to power the receiver. The second speed control would have the red wire to the receiver disconnectec, but you MUST keep the signal and ground leads intact. DO NOT cut the black wire to the receiver.

All items working from the receiver need to maintain a common ground, which is the reference level for the signal lead. If you remove it, then the speed control will not operate correctly because the incoming signal will not have a reference.

smokingcrater

lots of micro heli users that run seperates run with both the black and red cut. they are both grounded through the battery ground, which gives the common ground reference. I've personally run two different helis, one brushless, one conventional, using the setup shown in the posted image above (with both wires cut), and no problems what so ever, but your mileage may vary.

wisdom-seeker

This is probably a bad idea to run with the black wire cut to the receiver. The ground reference supplied by the battery ground lead is subject to voltage shift depending on the resistance and current in the battery wire. If it were my heli, I'd keep the best references possible on the signal connections.

Lynx

This is a Catch-22 situation. If you cut both the positive and negative leads from one of the ESC's the one that has them cut is subject to more voltage shift from only having a battery reference, yet if you don't cut it you have a ground loop which can cause problems in it's own right. I would personally avoid the ground loop situation, and cut both. Ground loops encourage noises to amplify, with digital servo's this can be even worse because of the increased frequencies the servo-motors are run at, and with high frequency ESC's which are common now with a ground loop you're just begging for harmonic interference, especially with two ESC's possibly running at the same frequency slightly out of phase.