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May 06, 2005, 03:27 AM
Registered User
Danny Troy's Avatar

2 brushless motors with one ESC?


I know this has probably been discussed in the past but here it goes again.

I have a couple of applications, one being a tiny twin flying wing (the MiniTwin), and I was wondering if people are successfully powering two BL motors using one ESC. I have heard that as long as the two motors are exactly the same, and the ESC isn't overloaded, it would work.

Has anyone actually been using this type setup?

Danny
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May 06, 2005, 08:05 AM
Registered User
Tim Cullip's Avatar
I've used a Phoenix CC10 driving two cdrom motors in a scratch built p38 lightning.
The motors were wired for fairly low power - together at full power they draw about 3amps
on a 2 cell lipo setup.

I think startup is the big hurdle with 2 motors off of one controller. If you can get reliable starts, then running should be fine.

Mine starts a little rough sometimes, and fails to start both maybe 2% of the time.
I love my setup. Again, mine is a small, low powered setup: all up weight on this 28" bird is 6oz.
May 06, 2005, 02:33 PM
Registered User
Danny Troy's Avatar
Thanks for the info Tim. That's what I wanted to hear. And BTW, nice P-38. Mine still has the stock S-480s, but it flys like a dream. I forgot the manufacturer, but I bought it from Hobby Lobby a few years ago. This one has a fiberglass fuse and built-up wings, so it needs the 480s for power.

I'm thinking for the small twin I can use my 18 amp ESC for the two little Feigao motors. That should be well within the ESC limits. For a twin BP-21 application I'll use my Phoenix 25 and see how that works out. It might be marginal at full power though.
Oct 29, 2005, 01:49 PM
Go FASST or go home...
Ben_E's Avatar
Quote:
Originally Posted by Danny Troy
Thanks for the info Tim. That's what I wanted to hear. And BTW, nice P-38. Mine still has the stock S-480s, but it flys like a dream. I forgot the manufacturer, but I bought it from Hobby Lobby a few years ago. This one has a fiberglass fuse and built-up wings, so it needs the 480s for power.

I'm thinking for the small twin I can use my 18 amp ESC for the two little Feigao motors. That should be well within the ESC limits. For a twin BP-21 application I'll use my Phoenix 25 and see how that works out. It might be marginal at full power though.
How did it go?
Did you get the two feigaos to work on one ESC?

BEn_E
Oct 29, 2005, 03:41 PM
Registered User
Danny Troy's Avatar
No good. On the mini flying wing I had to go with two 10 amp ESCs. On the P-38 I just went with two inexpensive 18A ESCs feeding a pair of Himax inrunners. I recently bought a CoolRunning ESC and I'd be interested to know if anyone tried to run two motors with one of these ESCs. The problem is probably the ESC, not the motor.
Oct 29, 2005, 06:29 PM
volare est vivere
ray foley's Avatar
The rule for multi-motor brushless applications is: N motors, N ESCs, 1 to N batteries.

Nothing else is reliable or particularly safe.

And yeah, this subject has been raked over time after time. Same results, see above.

Also:
Make sure you remove the red lead (+v) from the connectors of all but one ESC or make up a y circuit that only gets +v from one ESC.

Good luck, ray foley
Oct 29, 2005, 06:36 PM
MKH
MKH
Registered User
www.m-a-e.com has a new design out, that uses twin westport cdrom motors and one esc. You could write Randy and ask what the secret is.
MKH
Oct 29, 2005, 06:43 PM
Registered User
Quote:
Originally Posted by ray foley
The rule for multi-motor brushless applications is: N motors, N ESCs, 1 to N batteries.

Nothing else is reliable or particularly safe.

And yeah, this subject has been raked over time after time. Same results, see above.

Also:
Make sure you remove the red lead (+v) from the connectors of all but one ESC or make up a y circuit that only gets +v from one ESC.

Good luck, ray foley
What is an "N" Motor? Also what are "N" ESC's & Batteries. Please define "N".

-Thanks-

Mike
Oct 29, 2005, 09:06 PM
volare est vivere
ray foley's Avatar
Remember algebra? N is a variable, sometimes read as "the number of" whatever you like.

So if N=2 then the multimotor rule becomes, 2 motors, 2 ESCs, 1 or 2 batteries.

Or if n=3 then the multimotor rule becomes, 3 motors, 3 ESCs, 1 to 3 batteries.

For larger values of N (3,4,5,etc.) The rule still applies but the wiring becomes more complex. This application is left to the student as an academic exercise.


And for you college calculus types:

What is the integral of (1/cabin)d(cabin)?

ttfn rjf
Oct 29, 2005, 11:54 PM
Registered User
Quote:
Originally Posted by ray foley
Remember algebra? N is a variable, sometimes read as "the number of" whatever you like.

So if N=2 then the multimotor rule becomes, 2 motors, 2 ESCs, 1 or 2 batteries.

Or if n=3 then the multimotor rule becomes, 3 motors, 3 ESCs, 1 to 3 batteries.

For larger values of N (3,4,5,etc.) The rule still applies but the wiring becomes more complex. This application is left to the student as an academic exercise.


And for you college calculus types:

What is the integral of (1/cabin)d(cabin)?

ttfn rjf
Thanks:
That's the complicated way of saying "You need (2) Brushless ESC's to run (2) Brushless motors.

-Mike-
Oct 30, 2005, 12:06 AM
Boffin
rpage53's Avatar
Quote:
Originally Posted by ray foley
Nothing else is reliable or particularly safe.
Kontronik has sold a twin brushless setup for years that works just fine. CC are not the best choice for twins but some setups work.
http://www.kontronik.com/DSet400480Motse.htm
Oct 30, 2005, 08:44 AM
Crash Master
Gene Bond's Avatar
Starting twins on 1 esc:
It's not good practice.
It may work on very closely matched motors.
I will fail when you least expect it and need it most.
You can easily burn up an esc if one fails to start.
You can easily spin in a twin if only one motor runs.

Factory matched systems probably work fine, but is there a model replacement guarantee?

Nuff said?
Oct 30, 2005, 09:18 AM
Englishman in Japan
Spadkun's Avatar
Try to make sure everything is identical, same motors, same length of wires etc.
Connect to the same phases on both motors.
I read a lot about it , seems you have a 50/50 chance.
I have profile P38 with two Komodo CD motors running on a single CC25 controller, works every time.
Good luck
Oct 30, 2005, 10:34 PM
volare est vivere
ray foley's Avatar
For you calculus buffs out there.

What is the integral of (1/cabin)d(cabin)?

answer: natural log cabin.

groans expected

rjf
Oct 31, 2005, 01:28 AM
SoCal, Year Round Flying!
bmiller's Avatar
About 4 years ago I had a twinjet w/ 2 bl aveox1005/5 on one 60amp bl ESC. drew 45-50Amps, just had to make sure both motors started quickly and it worked fine. It did blow the big capacitor once which I replaced and had no further problems.
At one time mutiplex sold a dual motor bl ESC, but it wasn't rated for the amps I was pulling. don't know if they make it.


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