Help with 2wd please, front motor shudders

[senlin]

I have been working on this bike for many months. I have finally got it going- sort of. I have 2 grinfineon 7240 controllers, Cycle analyst 3-WP, and the CA3-WP Dual Controller Splitter to connect to the controllers. The throttle and ebrakes connect to the CA-3. I have built a powerful 70v LTO battery pack, it can easily handle the 2x40= 80amps. I have set the shunt value to half as intructed.

Here's the problem, both motors work great independently, however when they are both connected to the CA3 the front one always shudders badly, and the controller starts flashing, indicating sensorless mode. If I only connect to the front motor and pull out other splitter cable to the rear motor controller, I can ride fine fwd only. I can do the opposite and ride rwd only. Just can't get the 2wd, always the front hub motor that shudders, even if I switch the splitter cable around the other way?

Its giving me the shits and I'm going insane, I bought the ca3 and WP splitter to make the 2wd wiring easy. I'm waiting for GRIN to get back to me. In the meantime I'm hoping someone can help. It's actually surprisingly powerful with 1 motor, can't wait to feel the full power from both motors. I've fiddled heaps with the CA3 setting but nothing so far stops the problem, I've read hours of post on ES. Really hoping someone can help.

 

[E-HP]

Here's the problem, both motors work great independently, however when they are both connected to the CA3 the front one always shudders badly, and the controller starts flashing, indicating sensorless mode. If I only connect to the front motor and pull out other splitter cable to the rear motor controller, I can ride fine fwd only. I can do the opposite and ride rwd only. Just can't get the 2wd, always the front hub motor that shudders, even if I switch the splitter cable around the other way?

Just thinking out loud here, but the sensorless mode may be a clue that there's a conflict with the hall signals. The CA determines speed from a hall signal from the motor, through the controller (I think). Instead of disconnecting the second controller by bypassing the splitter cable, can you try keeping it connected, but disconnect the phase and hall connectors to the rear motor, to see if the front motor functions? I don't know what to expect, but just thinking whether that may indicate that the hall signals have a conflict when everything is connected.

 

[senlin]

Thank you E-HP. I did what you suggested, kept the splitter cable connected and disconnected the phase and halls to the rear motor (in this case phase and halls are all wrapped together in L10 cable). Yes you are onto something, the front motor spins smoothly, red light on controller does not flash.

I thought the CA3 takes care of all this by using the wp splitter and running throttle into CA itself. To be honest I don't fully understand how it works, I'm hoping its just something in the CA3 settings I need to change? I inputted half the shunt value of the controllers and changed to HI setting. I wasn't aware of any other settings I need to change?

Its been almost a week now and the boffins at GRIN haven't got back to me, they have been really helpful with other queries, maybe they are super busy ATM.

 

[thundercamel]

Good work E-HP. So each motor needs to have halls connected to their respective controller, but only one set of halls also goes to the CA3 for speed measurement.

 

[E-HP]

Good work E-HP. So each motor needs to have halls connected to their respective controller, but only one set of halls also goes to the CA3 for speed measurement.

Ya, seems odd though. You would think they would have handled that through the splitter cable, like having one of the two connectors with the "Sp(yellow)" wire going to one controller and not to the other. I guess opening one controller and snipping the wire might be a way to get it working, but I'm guessing there's another solution.

 

[senlin]

Yeah, I'm sure they wouldn't have designed it to run sensored for only 1 motor?

 

[E-HP]

Yeah, I'm sure they wouldn't have designed it to run sensored for only 1 motor?

That's a thought. I believe sensored smooths the start up, but if you assume two motors, I guess the sensored would provide the initial motion for the other motor. It will be interesting to see what Grin says.

Also, in the photos, it seems like the two connectors are color coded. Do both HIGOs have pin #2 (Speedo)?

 

[senlin]

The one with the red band has speedo, temp sensor, it has to be plugged in to work, so if its plugged to front motor controller and I pull out the rear plug, fwd will work. If I pull the red one out and leave the other going to the rear motor, nothing will work.

 

[senlin]

I've been reading through teklektik's 2wd thread. I know there have been lots of issues with running 2wd setups from 1 throttle, believe me I have read a lot of threads, eg regarding common ground problems between the two controllers. Probably in my ignorance, as I am definitely no electrical expert, I was hoping the CA3 wp splitter cable with throttle going directly to the CA3 would avoid these issues. It looks like it hasn't.

It was interesting that teklektik uses an analog potentiometer magura throttle as it causes less problems with the 2wd throttle issues than the newer throttles (I think they are mostly hall sensor style now). I'm wandering if this is worth trying, however not sure if it will work directly plugged into the CA3?

Forgive me for my ignorance if this is a silly idea but I'm getting desperate. I may just end up running two separate throttles which is not what I really wanted. Any ideas would be greatly appreciated.

 

[E-HP]

Does the connector without the red stripe have the same number of pins as the red striped connector?

 

[LewTwo]

Justin from Grin Technologies has a long youtube video on "A guide to multi-motor (2WD and 3WD) ebike drive systems":
https://youtu.be/Ub4EP2_mAds

If I remember correctly I believe on of his suggestions was to run the front motor at a slightly higher power level than the rear motor.

Strike that ... I am getting senile.

 

[senlin]

Does the connector without the red stripe have the same number of pins as the red striped connector?

Thanks for getting back to me. I just checked, both have 8 pins. I'm guessing the speedo and thermal pins are only active on the red stripe Higo.
Here is the pin layout of the connector.


https://ebikes.ca/pub/media/porto/web/images/boxed_bg.png

 

[senlin]

Justin from Grin Technologies has a long youtube video on "A guide to multi-motor (2WD and 3WD) ebike drive systems":
https://youtu.be/Ub4EP2_mAds

If I remember correctly I believe on of his suggestions was to run the front motor at a slightly higher power level than the rear motor.

Thanks LewTwo. Actually that was the video that inspired me to do a 2wd build. I've been fiddling around with the CA settings and can't see anything that controls the power levels individually to 2 motors. Do you know how it would be done? I'll re-watch the video to see if I can figure out how he does it. Thanks.

 

[LewTwo]

Nope but I do note he has a wiring diagram of the splitter in the video (can not find it on their site). perhaps this screen capture may be of some help.

 

[LewTwo]

Another thought ...
I note the skateboard folks have some dual motor controllers up to 200 Amps.
Trying searching for: Flipsky Dual Electronic Speed Controller

They ain't cheap but it is a thought.

 

[E-HP]

Can you check continuity between the fake pin 2 and the rest of the pins on both connectors? Maybe check all three fake pins, to make sure they aren't shorted somehow. I'm leaning toward a defective splitter cable.

 

[senlin]

Another thought ...
I note the skateboard folks have some dual motor controllers up to 200 Amps.
Trying searching for: Flipsky Dual Electronic Speed Controller

They ain't cheap but it is a thought.

I had a look at them, really nice, one of them even says traction setting, if that's what I'm thinking it would be a great tool to stop front wheel spin out.
Aliexpress has an interesting 2wd fatbike kit with a 2 motor controller, although a 48v 25amp controller:
https://www.aliexpress.com/item/1005002012472536.html?spm=a2g0s.8937460.0.0.59a12e0eDdJRkq

 

[senlin]

Can you check continuity between the fake pin 2 and the rest of the pins on both connectors? Maybe check all three fake pins, to make sure they aren't shorted somehow. I'm leaning toward a defective splitter cable.

I was hoping you were right, however conductivity seems to be correct. Pins 2,4 and 7 on the un-banded connector, don't have conductivity through the splitter which is correct. I tested all three of them to see if they are conducting to any other pins, they are not.

There was a big thread back in 2009.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=12356&hilit=2wd+problem
From reading this, it seems there can be an issue when the common ground wires are coming together from the 2 controllers and this causes problems. In the thread they join together the grounds from the 2 controllers directly which helps it, according to the thread the problem is worse with high power, amp setups. Its a bit beyond me and I don't really understand it, but I am wandering if something like this is happening in my setup?

 

[LewTwo]

There was a big thread back in 2009.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=12356&hilit=2wd+problem
From reading this, it seems there can be an issue when the common ground wires are coming together from the 2 controllers and this causes problems. In the thread they join together the grounds from the 2 controllers directly which helps it, according to the thread the problem is worse with high power, amp setups. Its a bit beyond me and I don't really understand it, but I am wandering if something like this is happening in my setup?

hmmmmm .... that is a bit of a long read. Not as bad as the "E-S Stealth Electric Bike Owners" thread ...

Seems they never really solved the electronic problem. Closely joining the ground planes seems to have only partially resolved the problem. In the the end the solution was two separate control systems with throttles that were mechanically joined. Amberwolf suggested building an external throttle that optically separated the two systems but I did not see where anyone followed up on that. Another approach might be a MPU that monitors the power applied to both controllers via separate shunts and then drives the controllers proportionally via the throttle or PAS inputs. The PAS signal is a "pulse train" and thus bypasses some of the voltage level problems associated with the analog throttle input.m My eBikeLing controller uses that approach (throttle drives the PAS system) and I do NOT like it.

The only solution that fully addresses the problem seems to be a controller that is designed to drive two motors.

P.S.
Do you plan to add a second seat to the rear seat post for the video photographer ? :wink:

 

[E-HP]

Its a bit beyond me and I don't really understand it, but I am wandering if something like this is happening in my setup?

The error should be a clue of some sort. If you plug the red lead into the front motor controller, and the other into the rear controller, does the shudder symptom shift between front and rear? I'm not sure what all of the issues that would make the controller change from sensored to sensorless operation, but I think hall issues is one of them. I've also read on the forum about hall signals being affected by electrical noise, so maybe something is causing interference just by how the wires are run, so maybe having the controllers located close together may be an issue.

 

[senlin]

The only solution that fully addresses the problem seems to be a controller that is designed to drive two motors.

Yeah it seems to be a difficult issue, I've been looking more at those flipsky controllers, they are great, very programmable, I would have definitely considered one of them if I new about them before I started this. I've ordered a half twist throttle, some people say it works well with a thumb throttle, have them next to each other and as you twist the throttle your thumb moves the thumb throttle. At least I'll be able to feel what the 2wd torque is like at last. I'll have one throttle through the CA so I can use the regen braking, and the other directly into the second controller. If I can eventually get a single throttle working I would prefer it.

I'm using it as a single seater so no rear camerman . I used a tandem frame to have room for the big LTO batteries and also because the rider weight is more on the front wheel so hopefully front wheel spinout will not be a problem. I also like the long low look. Being designed to carry two people I reasoned that it will be strong enough to carry heavy batteries. Main problem is lack of suspension as I thought it would be, even with the biggest tyres I could fit and low tyre pressure, if the road is a bit ruff it doesn't feel good. It is by no means a practical build, does not look remotely road legal, but I have loved building it and despite all the problems along the way I have learnt so much. I'm planning my second build now and feel a lot more confident in my abilities from doing this one.

I'll do a before & after thing on ES once I can run both motors together. Thanks for letting me know about those flipsky controllers, I had no idea those board guys run so much power: Take a look at this guy
https://www.youtube.com/watch?v=HssSMae3k8I

 

[senlin]

The error should be a clue of some sort. If you plug the red lead into the front motor controller, and the other into the rear controller, does the shudder symptom shift between front and rear? I'm not sure what all of the issues that would make the controller change from sensored to sensorless operation, but I think hall issues is one of them. I've also read on the forum about hall signals being affected by electrical noise, so maybe something is causing interference just by how the wires are run, so maybe having the controllers located close together may be an issue.

Thanks E-HP. I had a go moving the controllers apart from each other this morning, still same problem. The weird thing is that if I change the red band lead around to the other controller, its always the front motor that shudders. Its more of a misfire feeling because it doesn't really smooth out as speed increases. I've ordered a half twist throttle, so for now I'll run separate throttles so at least I can have the two motors running simultaneously. The more I read, it seems to be a common issue with higher powered 2wd setups. :?

 

[LewTwo]

I'll do a before & after thing on ES once I can run both motors together. Thanks for letting me know about those flipsky controllers, I had no idea those board guys run so much power: Take a look at this guy
https://www.youtube.com/watch?v=HssSMae3k8I

GEEZ .... a 30-40 MPH skateboard. '
Tis a tad ironic that he has to be somewhere in Europe where they restrict E-Bikes to 15 MPH

 

[senlin]

These unicycle guys are the bravest (or craziest). It just looks so scary doing what they do at the speeds they do!
But definitely no 2wd issues to worry about
https://www.youtube.com/watch?v=d2WRG880sm0

 

[E-HP]

Are you able to suspend or elevate the bike to see how it behaves no load?