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Old Sep 30, 2005, 06:15 PM
Bidule mAV
Terrigal NSW Aus
Joined Aug 2005
9 Posts
Problems running 2 motors on one ESC...help please

HI everyone. I need some help regarding my thesis project. I am building a mini UAV for my thesis. It is powered by 2 Feigao 12x22mm 5250KV Brushless motors. I am running an IPS gearbox, 2S 340mAh Kokam Lipo with a CC Phx 10 controller. The model is now finished but I am having problems with the ESC.

I have been told you can run two motors of the ESC sucessfully. When I open the throttle one motor spins up while the other windmills. Then I close the throttle and the other spins up vice versa. Do I have to change the timing advance or something? Your help would be appreciated.
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Old Sep 30, 2005, 08:18 PM
Registered User
Blackpool, Great Britain (UK)
Joined Sep 2004
63 Posts
Experience says that two brushless motors on one ESC will work sometimes but most of the time they won't.

Your setup obviously is one that's not happy and probably the best advice would be to simply stick another ESC in there. I doubt very much if tinkering with settings will help but there may be others out there who know different.

Not the cheapest way around the problem but it will work.

One thing you should check is current draw. I tried my motors separately to find base data to work from and found that, on the few times the pair did run on the one ESC, the current drawn was considerably higher than twice the single motor figure. Both the ESC and the motors got hot quite quickly.

Chris Bromley
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Old Sep 30, 2005, 10:44 PM
Watts your motivation
roccobro's Avatar
San Bernardino, CA
Joined Aug 2003
6,512 Posts
I've heard mixed things about the little Feigao's. Manufacturer ( I think) says they will not work off one ESC, others have proved this wrong. It could also be the firmware verison of the ESC. Some of the earlier CC versions had trouble with dual motors and some outrunners.

Definitely check the current draw of one motor as Chris suggests.

Justin
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Old Sep 30, 2005, 10:46 PM
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stone_axe's Avatar
Louisville, KY
Joined Apr 2001
665 Posts
It's my understanding that 2 BL motors on 1 ESC is not really doable.
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Old Sep 30, 2005, 11:03 PM
Watts your motivation
roccobro's Avatar
San Bernardino, CA
Joined Aug 2003
6,512 Posts
The motors just need to be the identically the same. You'd think that production made motors would be identical, but sometimes they are not. The hardest would be making two CD motors that were identically hand wound. But they are done quite regularly now.

Some brand of ESC's just can't do it at all. Castle ESC's have been really good at dual motor synch'ing.

Justin
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Old Oct 01, 2005, 05:16 PM
Bidule mAV
Terrigal NSW Aus
Joined Aug 2005
9 Posts
I have run one motor on a test rig using a power supply and various gear ratios. The current draw is well withing the ESC. The Feigaos are rated to a max of 2A.

I am using the latest software for the ESC. Maybe I should try an older version?

Thanks everyone for your advise.
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Old Oct 01, 2005, 05:57 PM
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Palmdale, CA
Joined Oct 2000
13,208 Posts
I would go to two ESCs, with one slaved to the other, with its control on a knob or slider. I used this approach on my twin brushed airplane to investigate the effects of power on asymmetric handling..
I could stop either motor or reduce power to either motor.
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