# Twin controllers



## grayballs (Aug 27, 2008)

A buddy of mine approached me recently and asked about using a couple of my 72v Curtis controllers (I bought a bunch of them a while back) and 2 motors to power his Metro glider. My first thought was "no sweat, the big issue would be building the reduction box to divide the drive axels". CNC mill to the rescue,, that part I'm sure I can do.
More thought got me to wondering about balancing the current draw between the controllers. Is any one out there running a similar setup?
I think the twin drive would provide plenty of power for direct drive and a differential for turning, but might tend to work one motor harder than the other.
Any thoughts?


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## Qer (May 7, 2008)

grayballs said:


> More thought got me to wondering about balancing the current draw between the controllers. Is any one out there running a similar setup


Using more than one controller per motor? Forget about it. There's a thread about it somewhere in the forum that concludes that it won't work and you probably will blow up the controllers trying.

Using one motor and controller setup per side shouldn't be any problem though, not more than that you possibly will tax the batteries seriously if you floor it. But to avoid that the car pulls sideways you want as identical setup as possible on both sides so even minimal differences might mean that you constantly have to keep your hand on the wheel to compensate for uneven torque. Not very comfortable in the long run.


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## grayballs (Aug 27, 2008)

I think the idea was 2 controllers, 2 motors,, one for each axel. The Curtis controllers are in hand, and the ADC ?91-4003 motors are cheap, proven, and available. The motors come from the factory set up for CCWDE rotation so the transmission gets replaced with a side by side reduction box. Common bus from the battery pack and plenty of power, IMO. Hopefully it is just a matter of adjusting the pots. Plus, his idea gives him the ability to limp home should any one part fail (like that would ever happen).


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## Qer (May 7, 2008)

grayballs said:


> I think the idea was 2 controllers, 2 motors,, one for each axel. The Curtis controllers are in hand, and the ADC ?91-4003 motors are cheap, proven, and available. The motors come from the factory set up for CCWDE rotation so the transmission gets replaced with a side by side reduction box. Common bus from the battery pack and plenty of power, IMO. Hopefully it is just a matter of adjusting the pots. Plus, his idea gives him the ability to limp home should any one part fail (like that would ever happen).


I don't think it should be a problem then. Personally I'd use a high quality stereo potentiometer to make sure the two channels are as equal as possible, especially cheaper potentiometers can differ a lot in linearity and also resistance between the channels. But that's just how I would solve it, no guarantee it's the best way. 

If you want to limp home you need two contactors or breakers so you can power off one side while the other one runs since it's unfortunately not unheard of that a controller can suffer a total melt-down that gives the motor full power.


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## grayballs (Aug 27, 2008)

Qer said:


> If you want to limp home you need two contactors or breakers so you can power off one side while the other one runs since it's unfortunately not unheard of that a controller can suffer a total melt-down that gives the motor full power.


 
That was the idea, common bus to the safety and control circuits, then duplicate everything.


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## Qer (May 7, 2008)

grayballs said:


> That was the idea, common bus to the safety and control circuits, then duplicate everything.


Well then, go for it! Don't forget to document well and keep us updated!


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