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Old May 28, 2002, 02:47 PM
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TheAddler's Avatar
Sonoma County, California
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Twin Motors - How to wire?

I'm curious about useing twin (or more) motors on a plane. How do you go about htis? Do you need two speed controls, two batteries? If you can only use one battery and speed control, what does this do to the amp draw on the battery? And again, id you can use a singal speed control, do you just split the wires? Thanks in advance for all help!
Darren
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Old May 28, 2002, 05:06 PM
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Norfolk, England
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Darren,
Use one ESC and one battery pack. The effect on the current drain will depend on how you wire the motors. Wired in series, that's two + leads from the ESC to the two motor + teminals, and two - leads from the ESC to the motor - teminals, you will, in theory double the curent draw, but get much more power than from a single motor. Each motor 'sees' all the cells in the pack.
Parallel wired motors are totally different. Run the ESC + to the + of one motor. run the - of that motor to the + of the other motor, and the motor - to the ESC -. Think of it as a complete loop. This leaves current draw at roughly what it would be for just one motor, but reduce the power of both motors since each is only 'seeing' half the pack.

How you wire them all depends on the amount of power your model will need, compared to what duration you need. A faster model, with less duration gets wired in series, whereas a slower, more floaty model can often be wired in parallel for longer flights.

This is a very basic description, only trial and error will determine your individual needs. That, or a good computer program to work it all out.

Pete
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Old May 28, 2002, 05:49 PM
Rod
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Canada, BC, Kelowna
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Darren, I disagree with Pete's comments.
A parallel connected pair of motors connects the 2 positive leads from ESC to each motor +, and 2 negative leads from ESC to each motor -. A series motor connection connects the + lead from ESC to motor #1 +, - lead from motor #1 goes to + connection of motor # 2, - connection from motor # 2 goes to - connection of ESC.
As a general rule you can run Speed 400's and smaller in a parallel connection, where the total amps draw on the batteries will be in the 16- 20 amp range, ( motors will each see 8 - 10 amps).
Larger motors should be connected in series so that the amps draw on the batteries will be in the 30 - 40 amp range with each motor seeing 15 - 20 amps. If you connect these larger motors in parallel each will see 30 - 40 amps and your batteries will see 60 - 80 amps which will cause need for a large ESC and will toast your batteries .
Two ESC's can be used and Y connected to your receiver, disabling one bec.
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Old May 28, 2002, 06:00 PM
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Agreed, Peter has the names of the connection types the wrong way round but other than that you are basically agreeing.

For series connection you need twice as many cells i.e. if each motor is to see 8 cells you need 16 total. But the current is constant throughout the circuit so if each motor pulls 20A you only need a 20A controller.

For parallel the opposite is true, each motor sees all the cells so you only need 8 cells, but the total current is twice as much this time so for 20A at each motor you need at least a 40A controller. So you need larger cells.

Like much in this life it's all trade-off.

Steve
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Old May 28, 2002, 06:47 PM
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Thanks for the replies! I'm not too worried about the tradeoff of power vs amp draw and flight time. That stuff I'll play with and see what I like. I really just needed the wiring. I didn't want to fry anything for a 'dumb' mistake I'm playing with Zepron planes right now, and want to get this all figured out before I move on to some nicer scale models. Thanks again!
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Old May 29, 2002, 03:29 AM
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Norfolk, England
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Sorry about that, brain not working correctly - too many things going on at the same time. At least it was only the names I had wrong, it could have been worse.

Pete
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