How to wire one throttle to two controllers

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How to wire one throttle to two controllers

Postby el_walto » Sun Jul 03, 2011 3:11 pm

I'm making a 2 wheel drive setup. Can I safely parallel the three throttle wires? Here is my setup. I just want to make sure before i blow something up.

Ping 15Ah battery > 40a infinion > 9c front
Ping 16Ah battery > 40a infinion > 9c rear


*Edit
Yes i do have two cycle analysts for current limiting until i order my A123 from Cell_man
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Re: How to wire one throttle to two controllers

Postby el_walto » Sun Jul 03, 2011 5:23 pm

OK, i decided to just go for it and it all worked out fine. I just paralleled the 3 connections and made a Y Splitter. Works great, Can't wait to put 40 amps through each hub when i get a new battery.
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Re: How to wire one throttle to two controllers

Postby iovaykind » Sun Jul 03, 2011 9:36 pm

How do you manage to fit all those batteries on your bike lol Let me know if you find any improvement over one wheel drive. I've been thinking about it, but seems like it would only increase torque and not top speed
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Re: How to wire one throttle to two controllers

Postby el_walto » Sun Jul 03, 2011 10:26 pm

For some reason my top speed had gone up from 42km/h to 47km/h. I think it will be better for climbing hills also. I used to run 40amps into one hub and it would get really hot climbing large hills.

My new back motor seems much quieter than my front one. I think they are the same windings, but my rear hub is the newer one with the disc side cover. I think the 9Cont with the disc mount resonates much less or something.
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Re: How to wire one throttle to two controllers

Postby Rassy » Sun Jul 03, 2011 10:45 pm

EW, your results are similar to what I found when running two (or three) motors from one throttle. I was always careful to make sure the controllers and motors were just the same. If one of those motors wants to run faster than the other then it will end up working harder, so check for heat after some of your first rides.

I also just paralleled the three throttle wires, since I couldn't find any information on how to do it at the time. Some of the experts have chimed in since then, (this has been discussed a few times elsewhere on the forum) and said that was the wrong way to do it and might cause some problems, but again, I never experienced any problems. One additional thing I alwalys did was to also parallel all battery packs feeding the systems. I did this for two reasons. First, I wanted both motors to be running at the same voltage, and hence at the same speed. Also, I didn't want the battery packs to attempt to balance through the throttle wires.

I have used this setup on four or five different rigs, both brushed and brushless systems.

EDIT: As far as top speed, it does make sense that it increases, because the top loaded speed of a motor is always somewhere below unloaded speed and depends on the actual load. So neither motor has so carry as large of a load, hence it can run closer to it's unloaded speed.
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Re: How to wire one throttle to two controllers

Postby el_walto » Sun Jul 03, 2011 10:58 pm

Rassy wrote:I didn't want the battery packs to attempt to balance through the throttle wires.


Ok, now you got me scared. Do you think this actually happens? I think my batteries Y harness would have melted by now if this was the case.
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Re: How to wire one throttle to two controllers

Postby fechter » Mon Jul 04, 2011 12:40 am

If your batteries are not connected to each other, there is no current path, so no potential problem there.
If you were running two controllers off the same battery, you could then get a current loop in the throttle wires under some conditions. Two controllers going to the same motor is asking for smoke, but I've heard of it working before.
To run two controllers off the same pack, the negative battery wires from both should be connected to each other close to the controller and with equal length wires.

In any case, connecting the two 5v throttle wires together will create the possibility of backfeeding one controller's 5v line with the other one. If both have exactly the same voltage on the 5v line, no problem. To be safe, I would not connect one of the 5v lines. This means the controller with the 5v line still attached has to be turned on for the other one to work.
You could possibly use diodes to prevent any backfeeding, but the voltage drop in the diodes would probably cause the throttle to not reach 100%.

Backfeeding may not really cause a problem but the 5v regulator in the one with the most voltage may be supplying the all the control circuit current for both controllers and therefore run hotter. If it overheats, it can shut down.
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Re: How to wire one throttle to two controllers

Postby Arlo1 » Mon Jul 04, 2011 12:52 am

Interesting... Methods had major missfires running a dual motor dual controler setup!
My Leaf motor controller build. http://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer
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Re: How to wire one throttle to two controllers

Postby Rassy » Mon Jul 04, 2011 12:57 am

Okay, I didn't mean to scare you. I know nothing about how controllers and throttles work, but I think there is a +5V and a (common) ground from the controller to the throttle. If these are tied together, but the controllers get their power from separate batteries this would result in both batteries being grounded together but the +5V circuit is probably isolated (via diodes?) from the main battery positive. So my guess is no real problem. Maybe one of the experts will chime in on this issue again.

In any case, I still think paralleling the batteries makes sense because that keeps the voltage to each controller and motor system the same. This didn't present a problem on my initial systems, since I was using SLA at the time. However, when I used LiFePO4 batteries, I did bypass the BMS during discharge, making sure they were at the same voltage before hooking them together in parallel. A better solution would have been a single battery pack large enough to handle both motors.

I knew you said your battery packs were different sizes, but I just looked at your first post and I see they are 15AH and 16AH Pings, which are almost the same. Since LiFePO4 tends to operate at a pretty constant voltage until near the end, you probably won't have any problems unless you try to run them clear out, which isn't a good thing to do anyway. Your meter may tell the story, because if the voltage of one battery drops below the other the motor with the higher voltage will try to run faster, using more juice, which would then balance the two batteries. i.e., they may stay at the same voltage because of the mechanical link with no need of an electrical (parallel) link.

So in conclusion, sorry about being so long winded, what you are doing right now may make perfect sense and work better than any other technique. Let us know. :D

EDIT: What Fechter wrote while I was writing this is what I have seen before, i.e. not paralleling the 5V throttle wires together and instead just using the 5V wire from one of the controllers. I have never tried doing that, but if it could potentially save a controller may be well worth doing. I no longer use any multi-motor setups, so will not be doing any such tests myself.
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Re: How to wire one throttle to two controllers

Postby el_walto » Mon Jul 04, 2011 10:35 am

Arlo1 wrote:Interesting... Methods had major missfires running a dual motor dual controler setup!


I think methods was using one controller for two motors. I'm using two controllers with two motors.
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Re: How to wire one throttle to two controllers

Postby Arlo1 » Mon Jul 04, 2011 1:05 pm

el_walto wrote:
Arlo1 wrote:Interesting... Methods had major missfires running a dual motor dual controler setup!


I think methods was using one controller for two motors. I'm using two controllers with two motors.

Nope he had two seprate controlers one for each motor.
Edit: heres the link viewtopic.php?f=2&t=12356
My Leaf motor controller build. http://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer
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Re: How to wire one throttle to two controllers

Postby el_walto » Tue Jul 05, 2011 2:31 am

Arlo1 wrote:
el_walto wrote:
Arlo1 wrote:Interesting... Methods had major missfires running a dual motor dual controler setup!


I think methods was using one controller for two motors. I'm using two controllers with two motors.

Nope he had two seprate controlers one for each motor.
Edit: heres the link viewtopic.php?f=2&t=12356


Well it seems to be working fine for me, but my front motor was always noisy so maybe i don't notice. I'm thinking it might work for me because i have a separate battery going to each controller.
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Re: How to wire one throttle to two controllers

Postby ChinaPhil » Tue Jul 05, 2011 4:28 am

I am running two Cellman 350W geared hub motors, a controller for each, one common battery pack and one common throttle. One of the controllers is connected with just a single throttle wire - the signal line. This set up works well.

Phil
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Cellman 350W geared hubs, 2WD, hardtail; 12s Lithium Cobalt Oxide, 2 x 17A
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Re: How to wire one throttle to two controllers

Postby dogman dan » Tue Jul 05, 2011 6:22 am

Listen to Fetcher. The throttle doesn't need 5v input twice. So disconnect one of the inputs and potential problems vanish. So simple I could understand. All you need is two outputs, not two inputs.
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Re: How to wire one throttle to two controllers

Postby Arlo1 » Tue Jul 05, 2011 9:14 am

Yeh I plan to run two out puts off the same throttle as well but... You will need the batteries parreled to make the one 5 volt input work. I would do it the way fetcher said as well this is a forum he started and he is proly in the top 10 for smartest electric guys on here!
My Leaf motor controller build. http://endless-sphere.com/forums/viewto ... 27#p963227
My YSR build http://www.youtube.com/watch?v=BRo8r5g4NBg
RC and most types of Lithium batteries you MUST know your individual cell voltages charging and discharging.
Don't keep them were you cant afford smoke or fire!
Never above 4.2v never below 2.7v EVER!!!
HI power controller design. Game Changer
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Re: How to wire one throttle to two controllers

Postby el_walto » Tue Jul 05, 2011 10:12 am

Yeah, i should probably change a couple things, but it seems to be working fine the way it is.

Turns out my bike is actually more efficient with two hub motors. The two hub motors, at 25A each, got me to work faster, and with less AH used, than if i had used one hub motor at 40amps.
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