will one throttle run two different controllers

[diver]

I have two 5304 motors on my trike. one on the rear and one on the front. I have a shenzhen and an xlite new style controller. My quest is could one throttle run both of these controllers at the same time. if so would i just wire in the throttles like both red wires together and so on.. why am i doing this, cause i want to play,,lol heres a couple of pics to show what i want to do,, OH I JUST FOUND A THREAD ON THIS SORRY

thanks

 

[diver]

well so far i found that the red is that same and green and yellow have to be swaped going to the shenzhen controller. now to work on the halls and phase wires

 

[diver]

I had to use two xlite controllers, one new style and one old style. I think the shez controller is dead..What a differance in low end power now. Im really surprised at how much differance it makes.
thanks

 

[bobmcree]

if both controllers use the same ground, you only need to power the throttle from one of them. the throttle signal varies from about 1-5v and should drive the two controller loads in parallel. do not connect the throttle power wires from the two controllers, just the ground and throttle signal.

assuming that the same throttle voltage will produce about the same pwm duty cycle, the two controllers should work ok from a single throttle signal, since the motors are the same, and when one motor goes faster it reduces the load on the other so the latter motor speeds up, and they self-synchronize. remember that the throttle does not really control the speed; it just controls the PWM duty cycle, the ratio of on/off times of the current to the motor. looking at it this way it is fairly easy to see how the two controllers can work together.

the one caveat is to make sure that the throttle can drive the combined load of the two throttle circuits. to test this you can disconnect the motors and hook up the single throttle signal to both controller inputs, then watch the throttle voltage as you rotate it. You should see about the same voltage range as when the throttle is connected to only one controller. If this is not the case it might be necessary to make a minor mod to the controllers or just to buffer the throttle signal with an op amp to boost the current drive. If two completely different brands of controllers are used it might be necessary to gain or pad the throttle signal to one unit to make them match closely enough.

people have even run 2 brushless motors off a single controller; but this generally only works on sand or mud where the wheels can slip until the fall into sync. running 2 controllers from a single throttle is a much better solution. running 2 brushed motors off one controller is fine as long as it can handle the current. Sometimes people put 2 brushed motors in series to make sure they run the same current.

 

[solarbbq2003]

hi bob
on a similar subject, if you were going to run two controllers in parallel, to get very high amp controller to run one motor,
or maybe to keep controller temperature down,
would the hall sensors in each motor work in a similar manner as the throttle connect? know if anyone has tried?. Common ground ( I guess that means same battery source)

 

[diver]

Ok, i think i understand. the red wire from the controller, being power source should only be connected from one controller to throttle and cap off the other red wire from the other controller. as of right now i have both connected, but i will change that asap
thanks for the info

 

[fechter]

hi bob
on a similar subject, if you were going to run two controllers in parallel, to get very high amp controller to run one motor,
or maybe to keep controller temperature down,
would the hall sensors in each motor work in a similar manner as the throttle connect? know if anyone has tried?. Common ground ( I guess that means same battery source)

They have a common ground, but guys that have tried it blew up a lot of controllers. It seems the switching delay time can vary between controllers enough to get shoot through in the power stage. Poof.
If you wanted to parallel two controllers, it would be best to take the signal going into the gate driver and split that. This would take 6 signal wires and a ground between controllers.

On a split throttle setup, the two throttle ground wires are connected to the battery ground, so you really only need one of those too. Only the signal wire needs to be connected to both. It would be a good idea to match the length of the two main battery negative wires from the controllers to the connection point to keep the voltage difference between them as low as possible. If one controller had a longer ground wire, there could be a significant voltage drop across it at high current, causing an offset in the throttle signal. You could possibly get a high current in the throttle negative wires if they were connected.

 

[diver]

Disconnected one red voltage wire. seems to still run ok. At hi speeds it almost feels like one controller is shutting off then coming back on till speed evens out then all is ok. The controller that is connected to the CA shows good voltage and 25 amps, that is what i have that set on. no ca on other controller. at least now with hte heavy load on the trike it will start on its own on a hill. To me that itself is a big plus for my hips and knees.
thanks

 

[Rassy]

Interesting discusslion. I have been running different setups with both two and three controllers from one throttle for over two years. Up until now this was only with brushed motors. Always connected all three wires in parallel (positive, negative, and signal). Never have experienced any problems.

Having said that, Just started testing a new two wheel trailer with two brushless motors. Earlier last year I had one of these motors on a one wheel trailer behind my recumbent bike. It was too heavy, but would still spin out quite easily, and drew just over 40 amps during heavy acceleration or hill climbing. The two wheel trailer is working okay, but not quite as strong as I expected. Turns out it is only drawing a max of about 28 amps for each motor, even at near stall. I am thinking it is a throttle problem, perhaps not sending a high enough signal voltage. It is the same throttle that has been in use for dual brushed motors, but I never had any Watts Up meters on the old SLA batteries. I plan some more tests, but not anxious to replace the throttle until I am sure of the problem, because it is threaded through the handlebars and was a real bear to do.

Sorry for the hijack, but unless my problem is just a weak throttle it may be related to the above discussion.

 

[bobmcree]

hi bob
on a similar subject, if you were going to run two controllers in parallel, to get very high amp controller to run one motor,
or maybe to keep controller temperature down,
would the hall sensors in each motor work in a similar manner as the throttle connect? know if anyone has tried?. Common ground ( I guess that means same battery source)

i tend to agree with fechter that it would be better to take the gate drive from one controller and feed it just to the fets in the other, which is basically the same thing as adding a second set of fets to the first one.

in the crystalyte controllers they use a discrete transistor circuit to drive the high side fets that are switched at the pwm rate, and the 2101 driver directly drives the low side fets that are just switched for each cycle. This circuit will easily drive 4310s so i expect it will drive twice as many 4110's which have a lower miller charge. you might consider just adding a second set of heat sinked fets to one controller and parallel them with the original set, using 10 ohm resistors on the gates.

the best possible alternative would be to hack in where the controller drives the 2101 and use that signal to drive the 2101 in the second controller after disconnecting its original drive.

when connecting controllers together, if throttle power is 5v both controller voltages should be close and they are current limited, so the throttle power should still be provided without damaging either unit, but it is just not necessary.

when you run two motors i'm sure you know that if one pulls ahead the other has less work to do and they will generally work it out between them. two controllers would not have this kind of self-leveling system to force them to share the load.

 

[solarbbq2003]

thanks for the tips glad I asked before trying!