Need help for Dual Motor setup

pogihlang

10 mW
Joined
Mar 23, 2021
Messages
26
Hello guys. I bought an electric bike conversion kit. 2000w 48v rear hub motor. It is running smoothly. Now I'm planning to make a dual motor setup with same kit specs for the front hub. I want to run it with single battery, throttle and single LCD display (S830). I do some research to how to wired it but I cannot find info on how to wire single LCD display for two controllers. I constantly change PAS/mode level to limit my speed using the display monitor buttons. Can someone share it to me?
 
I think what you are describing is using two direct drive motors and although I never tried that, from what I have read here, it doesn't work well for 2WD because they cannot rotate totally independent of each other. But if you are talking about geared motors (or at least one), maybe this will apply.
I ran 2WD for about 8 years, mostly dual Q100's, but sometimes a Q100 up frt and an Ezee rear.
At first I tried two controllers w/ one throttle by keeping the controllers close together and using a short common ground. The throttle responses never really felt smooth, I suspect splitting the signal degraded it. This was before the inexpensive multi-function LCD displays were available, but, since they are digital in function, I don't see how two controllers could be tied into one display.
Running the frt. motor thru the aux. of a Cycle Analyst worked well, but eventually I went w/ two throttles, a thumb and a half-twist side by side on the left side (Three, if one counts PAS). This worked well because I came to understand that the frt. motor doesn't need to run all the time, over the years, it worked out to be approx. 1/3 rd of the time. In fact, running them both at the same time w/ the same power creates traction problems. Some sort of power deferential needs to be incorporated.
These days, I just use one motor, the added complexity and weight just wasn't worth it.
 
motomech said:
I think what you are describing is using two direct drive motors and although I never tried that, from what I have read here, it doesn't work well for 2WD because they cannot rotate totally independent of each other. But if you are talking about geared motors (or at least one), maybe this will apply.
I ran 2WD for about 8 years, mostly dual Q100's, but sometimes a Q100 up frt and an Ezee rear.
At first I tried two controllers w/ one throttle by keeping the controllers close together and using a short common ground. The throttle responses never really felt smooth, I suspect splitting the signal degraded it. This was before the inexpensive multi-function LCD displays were available, but, since they are digital in function, I don't see how two controllers could be tied into one display.
Running the frt. motor thru the aux. of a Cycle Analyst worked well, but eventually I went w/ two throttles, a thumb and a half-twist side by side on the left side (Three, if one counts PAS). This worked well because I came to understand that the frt. motor doesn't need to run all the time, over the years, it worked out to be approx. 1/3 rd of the time. In fact, running them both at the same time w/ the same power creates traction problems. Some sort of power deferential needs to be incorporated.
These days, I just use one motor, the added complexity and weight just wasn't worth it.

Yes, it will be a gearless direct drive hub motor. I was thinking, what if I make the wire from the controllers to be parallel to each wire connected to the Lcd display? Will it works?
 
Hi there. I just did something similar, I have a geared hub motor front and back, two controllers that are compatible, and one battery. For the display, I just have it read from one of the controllers. I currently have the throttle wires in parallel going to both controllers, which works great, I just did a snow trail ride here in Alaska and the AWD was awesome, compared to the previous rear wheel only, especially on steep hills or punchy snow. Anyway, the problem comes in with the PAS. I currently have the PAS going to both controllers, but the display can only accept speed input from one. If I tie both communication wires of the display (that give speed input) together for both controllers, I get an error. So, with only input from one controller then the other controller thinks speed is always zero, so it wants to go full bore, no matter what PAS level is selected. Perhaps someone with more knowledge on this could chime in, but seems like with two potential speeds from the two wheels (slipping on snow, mud) the display would always be confused with the duplicate input. So.... I will probably change this to PAS on rear wheel only, and let the throttle be for both wheels, so if I need the front wheel for tough terrain, I will use the throttle, which seems to work fine in a parallel wiring configuration. Your results may be different with a different controller/display combination, but this is my experience.
Another thing for your particular case with such large hub motors, you will want to make sure your battery, BMS, and all associated wiring can handle another 40A. I just have a 250W in the front, and just that little bit seems to be enough to keep the front wheel from being a liability in the soft stuff :)


Cheers,
 
LoopEride said:
Hi there. I just did something similar, I have a geared hub motor front and back, two controllers that are compatible, and one battery. For the display, I just have it read from one of the controllers. I currently have the throttle wires in parallel going to both controllers, which works great, I just did a snow trail ride here in Alaska and the AWD was awesome, compared to the previous rear wheel only, especially on steep hills or punchy snow. Anyway, the problem comes in with the PAS. I currently have the PAS going to both controllers, but the display can only accept speed input from one. If I tie both communication wires of the display (that give speed input) together for both controllers, I get an error. So, with only input from one controller then the other controller thinks speed is always zero, so it wants to go full bore, no matter what PAS level is selected. Perhaps someone with more knowledge on this could chime in, but seems like with two potential speeds from the two wheels (slipping on snow, mud) the display would always be confused with the duplicate input. So.... I will probably change this to PAS on rear wheel only, and let the throttle be for both wheels, so if I need the front wheel for tough terrain, I will use the throttle, which seems to work fine in a parallel wiring configuration. Your results may be different with a different controller/display combination, but this is my experience.
Another thing for your particular case with such large hub motors, you will want to make sure your battery, BMS, and all associated wiring can handle another 40A. I just have a 250W in the front, and just that little bit seems to be enough to keep the front wheel from being a liability in the soft stuff :)


Cheers,

I only used the twist throttle. I read that making parallel connections for signal and ground wire of the throttle will do but I like mine having control of the PAS level on the display monitor. I always adjust the level based on the traffic situation to limit my speed and set it to zero when parked for safety. I want one display to control the two motor controllers for that. Is that possible?
 
I suggest rethinking your plan as you are denying yourself a major part of why 2wd is so nice to have.

I have personally done multiple 2wd bikes (hub+hub and hub+mid) and have found that doubling everything but the battery is the way to go. PAS to each motor (share 1 sensor if using the same hub front+rear), 1 throttle for each thumb, Dual controllers with dual throttles, displays and thus dual PAS selection lets you make minor adjustments wheel to wheel that are necessary. A single throttle really shortchanges the amount of control you can achieve with a 2wd bike.

Many thousands of miles on my geared hub+geared hub commuter. Selectively using throttle lets you make all kinds of fine adjustments. Dual PAS individually selectable means you have very finely diced selectivity off PAS power.

For a dual hub street commuter it makes the most sense for me to run them together and just zoom down the road, dialing back the front in turns (or else... another reason for dual throttles). On the other hand, on trails my hub+mid trail monster is happiest and safest when I have very low power to the front hub with no throttle (PAS only) with very occasional throttle use only when its safe to open it up. Hit a root on full blast at speed and when the tire comes back down it had better not be cocked to one side.

It doesn't hurt that dual display/controllers is the easier way to set it all up.
img_20181204_074653-e1616021024527.jpg
 
MoneyPit said:
I suggest rethinking your plan as you are denying yourself a major part of why 2wd is so nice to have.

I have personally done multiple 2wd bikes (hub+hub and hub+mid) and have found that doubling everything but the battery is the way to go. PAS to each motor (share 1 sensor if using the same hub front+rear), 1 throttle for each thumb, Dual controllers with dual throttles, displays and thus dual PAS selection lets you make minor adjustments wheel to wheel that are necessary. A single throttle really shortchanges the amount of control you can achieve with a 2wd bike.

Many thousands of miles on my geared hub+geared hub commuter. Selectively using throttle lets you make all kinds of fine adjustments. Dual PAS individually selectable means you have very finely diced selectivity off PAS power.

For a dual hub street commuter it makes the most sense for me to run them together and just zoom down the road, dialing back the front in turns (or else... another reason for dual throttles). On the other hand, on trails my hub+mid trail monster is happiest and safest when I have very low power to the front hub with no throttle (PAS only) with very occasional throttle use only when its safe to open it up. Hit a root on full blast at speed and when the tire comes back down it had better not be cocked to one side.

It doesn't hurt that dual display/controllers is the easier way to set it all up.
img_20181204_074653-e1616021024527.jpg

Thank you for sharing. I guest I will do the dual lcd display for me to make it easy.
 
Just know up front that a 2wd bike is a real pain in the ass to put together compared to a more traditional conversion. Lots more work. Cable management ends up being a pretty big deal. But do it right and the results are well worth the extra effort.

pxl_20210220_221354498.jpg
 
motomech said:
Wow, that's one busy set of h.bars :lol:

Having a camera, a horn and a bunch of headlights doesn't make it any less busy looking. And the bag on the bars is what is hiding the front motor controller and its rats nest, with pockets I use for keys and phone and wallet (nowadays I keep a Mean Well 5a/320w charger on top of that front rack). And you're seeing some of the front rack deck/reflector that in that pic looks like its part of the bars. But its a daily driver. Everything there has a job.

img_20190405_181939-1-e1616023807134.jpg
 
MoneyPit said:
motomech said:
Wow, that's one busy set of h.bars :lol:

Having a camera, a horn and a bunch of headlights doesn't make it any less busy looking. And the bag on the bars is what is hiding the front motor controller and its rats nest, with pockets I use for keys and phone and wallet (nowadays I keep a Mean Well 5a/320w charger on top of that front rack). And you're seeing some of the front rack deck/reflector that in that pic looks like its part of the bars. But its a daily driver. Everything there has a job.

img_20190405_181939-1-e1616023807134.jpg

Another question bro. Since you have a lot of experience doing dual motor build I want to ask if my wiring for the key ignition switch w/ voltmeter will work? See photo.

With my current setup, single motor, key ignition is working. It prevents the display to switch on. Now Im planing to use it like what it is shown in the photo. Do you think it is possible?
 

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I never used an ignition switch, as it really isn't a theft deterrent. My ebikes that have been stolden weren't driven away. But I do use better locks these days.
If you lose the ignition switch, you will be there, right?
You won't need the Voltmeter (is it a real V.meter or a row of LED's?), because your displays will have that feature.
 
motomech said:
I never used an ignition switch, as it really isn't a theft deterrent. The ebikes that have been stolden weren't driven away. But I do use better locks these days.
If you lose the ignition switch, you will be there, right?
You won't need the Voltmeter (is it a real V.meter or a row of LED's?), because your displays will have that feature.

It is a voltmeter showing digital numbers. Like in the photo. It is much accurate than the value in the LCD.
 

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I agree with motomech. I have never used an ignition switch or, for that matter, a password on the display(s). If I need security I use a badass lock. And I actually have the cargo bikes I have to leave outside of a store insured against theft. For the commuter I'm lucky enough to have a locked garage at my work.
Funny... I had a digital lock/display/throttle similar to that on one of my first builds, but it had a broken wire connection and I never used it. Never gone there since.
 
As far as ign. switches/ Voltmeters go , that's a nice one. You could use it as "switch only turns on/off Voltmeter" (no run/no run circuit).
The first Voltmeter I used was was a LED digital like that, but I quickly found out if if it wasn't switched out of the circuit, it would deplete my batt. pack.
Then I snagged a really cool LCD from Luna (they no longer carry it) that I could just leave in the circuit, as it's drain is so sm.
It has a little button to illuminate for a minute or so. One of my most prized ebike accessories.
I have never noticed any difference in readings between LCD and LED Voltmeters.
 
I agree having a good heavy duty is the best way to prevent thief from stealing your bike but why not add extra lock to your system? 😁

Going back to my question, do you guys know if my wiring sketch is possible to switch on/off the two controllers?
 
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