Electric Twins
11-20-2003, 11:18 AM
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Electric Twins
I'm just about to build my first electric twin, a Twin Otter from MAN plans. I'm wondering if there is a tutorial somewhere on the net on how best to wire the motors up. Power will be 2 480 size motors. I'm assuming that 1 battery pack per motor is best? Do I need a special speed controller in this case, or do I need 2 regular ones? Thanks for any suggestions.
11-20-2003, 11:31 AM
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RE: Electric Twins
The easiest solution is one speed controller that can handle the amps of the two motors you're going to use, then wire them in parallel (both red wires from the motor to the positive output of the speed controller). The second solution is what you propose. A battery and speed controller for each motor. This allows the BEC of one of the controllers to drive the receiver and servos. This is done by disconnecting the red lead from the second speed controller, that way you have signal and ground to the receiver. However the Kyosho Learjet just hooked both speed controllers into the receiver with a !QUOT!Y!QUOT! connector and didn't eliminate the one connection. Seemed to work ok too.
11-20-2003, 12:53 PM
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RE: Electric Twins
I wouldn't use two controllers if you can avoid it. Otherwise, you may have one battery run down before the other one, and get an "engine out" situation.
11-21-2003, 02:32 PM
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RE: Electric Twins
OK, one controller regulating both motors makes sense to me. Do I then use 1 battery for both motors? This would require a 14 cell pack, correct? What would happen if suddenly one motor stopped asking for current, such as if a wire broke off the lug at the motor. Would the other motor then get the full 14.4V?
11-21-2003, 03:23 PM
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RE: Electric Twins
One of the most confusing subjects is series and parallel circuits.
One controller, with both motors wired in PARALLEL (+ to + to +, - to - to -) would only require a 7 or 8 cell pack, because in parallel, the motors share current, not voltage. If the wire on a motor were to break off, that motor would stop. Nothing else would happen.
If the motors were wired in SERIES (controller+ to motor1+, motor1- to motor2+, motor2- to controller -), that's a different story. In series, the motors share voltage, not current. You would need a 14 or 16 cell battery to make the voltage high enough so that both motors would produce enough power. If a wire broke off one motor, both motors would stop.
There are pros and cons to every motor wiring scheme.
One controller, with both motors wired in PARALLEL (+ to + to +, - to - to -) would only require a 7 or 8 cell pack, because in parallel, the motors share current, not voltage. If the wire on a motor were to break off, that motor would stop. Nothing else would happen.
If the motors were wired in SERIES (controller+ to motor1+, motor1- to motor2+, motor2- to controller -), that's a different story. In series, the motors share voltage, not current. You would need a 14 or 16 cell battery to make the voltage high enough so that both motors would produce enough power. If a wire broke off one motor, both motors would stop.
There are pros and cons to every motor wiring scheme.
