20KW 2WD having misfires (but can do a double burnout)

[Arlo1]

Hey Zappat thats awesome! I love the idea I think that would be so cool to have. Motocross bikes run rim locks and if you make enough power you will want to as well. I realy like the build though I realy want to go build that right now!

 

[methods]

That is a bad-ass bike Pat.
I use Baby Powder to mount tough downhill tires on the rim. I then set them down and step on the tire to get it to pop in.
I am amazed that you can run a 3" tire on such a tiny rim. I run similar 3" tires on Sun Double Wides.

Good job solving the grounding issue!

I second fechters note about real brakes - if something goes wrong you could lose your brakes.
I suggest a 2x4 on a hinge right behind the seat. You can step on it to slow down

Well.. I am jealous of your build.
I am going to have to make something like that now to show you up

-methods

P.S. Anyone else who has 2WD pictures -> Post them up!

 

[steveo]

That is a bad-ass bike Pat.
I use Baby Powder to mount tough downhill tires on the rim. I then set them down and step on the tire to get it to pop in.
I am amazed that you can run a 3" tire on such a tiny rim. I run similar 3" tires on Sun Double Wides.

Good job solving the grounding issue!

I second fechters note about real brakes - if something goes wrong you could lose your brakes.
I suggest a 2x4 on a hinge right behind the seat. You can step on it to slow down

Well.. I am jealous of your build.
I am going to have to make something like that now to show you up

-methods

P.S. Anyone else who has 2WD pictures -> Post them up!

Hey peps!

I am waiting on my bike from to do star delta 2wd with 16" wheels!!!

i can't wait1!! here is a sneek peak of my drag bike on a shitty bike chasie...

http://www.youtube.com/watch?v=FOMFlZVPf6I - 140ish pound rider

http://www.youtube.com/watch?v=dfef7JgL240&feature=related -190lbs rider

-steveo

 

[karma]

nice :wink:

 

[kfong]

What if you used (2) 250watt hub motors and were willing to pedal. A light weight setup like this out on the trails would be very tempting for me to try. Just not sure if it would equal a 500watt cyclone setup with gearing. I like to pedal while trail riding but would rather have power for the hill climbs and only bring just enough batteries for a 10 mile run. It's just a fun workout this way. Any one using lower power hub motors on the trails? Nice to have all the power you need but weight and having to pedal it if out of power is just not fun. Especially when exploring new trails.

My new line of thinking is to use 2 geared 250watt hub motors such 8fun or bafang. Less rolling resistance and higher torque, smaller size and weight, less stress then on one motor. Anyone doing something like this? Plus steel gears should make them last.

 

[rgody]

Time ago a friend and I installed 2 350W hub motors in one ebike ...
Here the video :
http://www.youtube.com/watch?v=QM35qeiYYN4
And here a picture :

We use 9C motors, two 33A controllers , 1 twist thotlle , and four 12V 14AH SLA battery pack.


I remember we just conected each black (ground) , and blue (speed reference) wires of both controllers to the throttle.
Im not sure but I think we use only one controller to feed the throtlle (red cable with 4.2 V or some like that).
We didnt open the controllers.

The behavior of ebike was like light electric tractor. very powerful. Not much speed were reached due high currents that 2 motors absorbed. (more than 45A for small but heavy 14AH SLA batts)

Regards
Rodrigo

 

[liveforphysics]

I am waiting on my bike from to do star delta 2wd with 16" wheels!!!

i can't wait1!! here is a sneek peak of my drag bike on a shitty bike chasie...

http://www.youtube.com/watch?v=FOMFlZVPf6I - 140ish pound rider

http://www.youtube.com/watch?v=dfef7JgL240&feature=related -190lbs rider

-steveo

Bike looks quick steve! Great work!

 

[karma]

Time ago a friend and I installed 2 350W hub motors in one ebike ...
Here the video :
http://www.youtube.com/watch?v=QM35qeiYYN4
And here a picture :

We use 9C motors, two 33A controllers , 1 twist thotlle , and four 12V 14AH SLA battery pack.


I remember we just conected each black (ground) , and blue (speed reference) wires of both controllers to the throttle.
Im not sure but I think we use only one controller to feed the throtlle (red cable with 4.2 V or some like that).
We didnt open the controllers.

The behavior of ebike was like light electric tractor. very powerful. Not much speed were reached due high currents that 2 motors absorbed. (more than 45A for small but heavy 14AH SLA batts)

Regards
Rodrigo

yes i remember that video you were one of the first to post that setup on youtube :wink:

 

[rgody]

I found other interesting 2x2wd vehicle :

More information :
http://rohorn.blogspot.com/2006/11/my-first-venture-into-recumbent-design.html

Note the 2 wheel steering system

More information : rohorn@mho.com

Regards

 

[methods]

That is GANGSTER

I am going to build a recumbent tadpole trike soon.
Just trying to figure out how I will get enough traction for what I want to do.

-methods

 

[Arlo1]

That is GANGSTER


Just trying to figure out how I will get enough traction for what I want to do.

-methods

2 or maybe 3? wheel drive?

 

[methods]

3WD

Two 10x6 9C's up front in 16" wheels
One 6x10 9C in the back in a 26" wheel?

I have the motors, controllers, and batteries.
I just need a frame.

-methods

 

[ZapPat]

3WD

Two 10x6 9C's up front in 16" wheels
One 6x10 9C in the back in a 26" wheel?

I have the motors, controllers, and batteries.
I just need a frame.

-methods

Sounds good for motor KV / wheel diameter ratios (0.60 vs 0.61).

But there's one problem. The front wheels on most all trikes are one sided mounted only. Any ideas on overcoming this problem?

I have been dreaming of this kind of trike myself for a while, but I was thinking of only a 2 motor, dual front wheel drive using two NC hubs. I've been checking out the KMX trikes similar to what Matt used (I think it was him) for that powerfull dual RC drive trike he made - they seem hefty and fairly cheap.

 

[MitchJi]

Hi,

But there's one problem. The front wheels on most all trikes are one sided mounted only. Any ideas on overcoming this problem?

Maybe:
http://endless-sphere.com/forums/viewtopic.php?f=3&t=13176

Can you use 2 hub drives on a Trike?

First of all you will have to find motors with a stub axle, which i think Renaisance cycles has for Clyte motors they sell.

 

[methods]

Back from the dead....

After my bad experience with this dangerous 2WD monster I decided to try an X5 again.

Well to hell with that. I have already replaced the hall sensors twice and last night I blew sparks out of the vent holes.
I am building another 2WD Bike

This time it will be my wife's downhill bike. It already has a 9x7 9C on the front and just yesterday I got a shipment of (20) Rear 26" 9x7 9C motors.
All I have to do is bolt one on the back and slap another controller in there.

IIRC Pat and found a solution to the misfire issue correct?
Didnt he just have to tie a solid ground between the two throttle grounds?

I think this time I am going to do something a little different.
I am going to run a much lower current limit on the front than on the back.
Maybe 20A on the front and 40A on the back.
I hope that this will improve the traction control issues.

-methods

 

[Arlo1]

Can't wait to see it! So with all the stuff you have wrecked is it still cheeper then driving a car to work?

 

[methods]

I dont do it because it is cheap or because it is green - I do it because it is bad ass. :wink:

-methods

 

[Arlo1]

Yup me too and now with all my scrapes and bruises I feel like a kid again! :lol:

 

[methods]

Finished lacing up a 9x7 rear.
It is ready to go.
I have no less than 23 universal torque arms now so I dont have to grind/weld up a 10mm wrench every time I want to build a new setup
I also have 80 miniature torque arms that I can use as blanks for welding up custom drops.
These things fit over the 9C axle like a glove! Almost too tight.

I am debating on drilling them out too.

-methods

 

[ZapPat]

IIRC Pat and found a solution to the misfire issue correct?
Didnt he just have to tie a solid ground between the two throttle grounds?

Yes, I did make two ground connections directly between the two PCBs with heavy wire. Note that this was done with 6FET infinion (116's really) controllers using IR4110's, and I have since ditched these for dual 12FETs (using 60V IR3006's) and have been using these for a while now. I did not fix the grounds of the new controllers together inside the cases as I did with the 6FET ones before - I just used 8AWG wires, as short as possible and connected them together outside the cases... and the throttle stutter problem is fairly noticeable. :|

Same problem as before - With the rear wheel locked, the front motor stutters as it spins. I am quite certain that the dual 6fet setup I had before was much more immune to this problem, but the rear controller wasn't up to the job and I had to pamper it too much. One day comming back from a ride I drove up the ramp back into my lab, but I went too fast and flipped off the ramp and hit the dual controller. The next time I turned on the breaker, sparks flew out of the thing!! This is what stimulated me into building up two new controllers for the bike. The 12FET PCBs don't lend themselves as well to the ground jumper mod since their heavy ground trace don't go all along the side of the board where the shunt is, but I have no idea what the 18fet PCBs look like. Anyways I decided to keep them seperate and not join the cases end to end, but now I have to live with much more throttle stutter on the takeoff.

I did look into the problem a bit recently to try and find the source, so connected my scope to various points on the controllers to see where the junk is comming from. It turns out it looks to be what I expected - when one of these controllers has a stalled motor it cuts out abruptly before trying again and again, and this causes a very big current spike in it's power lines. Of course these big current spikes create large voltage transients between the two controller's ground reference points, which is what craps up the throttle signal. I measured the amplitude of the ground differential spikes at up to 2V peak to peak which is more than enough to wreck havoc on the throttle signal. At least I am pretty sure this is what's going on.

I have been using the bike despite the startup throttle stutter since it's great for offroad use anyways (those big fat 20" tires have incredible grip!). I was driving though mud holes 6" deep the other day and had no problem getting into and back out of them even at low speeds and while navigating around rocks. I want to test out Fechter's dual throttle RC filter idea posted earlier here, but with winter coming on here I've been working more on my own controller project and been doing less bike work lately. The bike also got a flat again recently, and this time I'll be getting a motorbike tube for it, 'cause it's a devil to change. But I do what to try it on the snowmobile trails this winter, it sould be real fun with the 2wd! If I lived close to a sandpit I would be horsing around in there all the time with this thing, it's great fun for doing tight circles while it chucks the sand out from under both wheels at the same time!

I think this time I am going to do something a little different.
I am going to run a much lower current limit on the front than on the back.
Maybe 20A on the front and 40A on the back.
I hope that this will improve the traction control issues.

This is how I have mine setup right now, and yes it helps quite a bit with handling. But don't just play with the battery current limits, you can also play with the phase current limits without danger. Mine are setup right now like this (note that my shunts are soldered so the limits are actually a bit higher, no CA yet to confirm real currents):
Front: 40A battery, 60A phase
Rear: 57A battery, 150A phase
This combo helps avoid the front spining up too much at low speeds since it is limited by the phase limit during low speed acceleration. As your speed goes up, the front will be pulling you along almost as much as the rear so this will give you good high speed torque. Have fun playing with the front/back and battery/phase current limit ratios, and let us know what you find works well.

Pat

 

[methods]

You stole my phase current idea :?

Yes -> I have been thinking a lot about traction control and what is different between low RPM and high RPM
The easiest target is the phase current.
On my 18 fet controllers I am now to the point where I phase current limit up to about 20mph then I get a little turbo boost when it comes out of phase limiting.
Quite exciting

Thanks for your info on the grounding issues.
I am thinking that we may be able to solve this in a simple way...
Not sure what that is yet - but I am sure afterward everyone will be like "duh - yea - thats what I would have done"

You know I have noticed this misfire issue with just a single motor running 44V and a 20A current limit.
There is a problem with how they handled stalling / low RPM in the software.

I have 20 motors to play with and I have been challenged to build a 16" 9x7 9C so we will see.
Imagine a 9C at 88V on that small of a wheel......

-methods

 

[tostino]

Would running a lm317 right off the battery pack to power throttle, and then just splitting the return line to both controllers work? It'd probably be pretty inefficient, because you would need to get the pack voltage under 37v for the lm317. Lotsa heat waste in resistors .

Just a thought.

 

[ZapPat]

You stole my phase current idea :?

What can I tell you, great minds think alike

Thanks for your info on the grounding issues.

New update as promissed --> I've put my first 2wd bike (dual 26" hardtail) back together after fixing up the controller pair today. I did not mount the controller PCBs together as close as previously (that time I did both end to end with two short and thick jumpers between grounds on the edge of each board - see photo posted already). This time I stacked them belly to belly each in their own cases, and there are two short 10awg wires (under one inch) runing between the same two ground spots as before. I also beefed up the power cables to 12awg instead of of the 14 I used the first time. Both positive and negative leads of the controllers are about three inches total before joining to common points just out of the controllers.

Anyways, now for the important bit: The setup described above still exibits the throttle stutter problem, but it is not as bad as on my other monster 2wd bike that has no added ground jumpers between the two 12 FET controllers (just short power leads before joining ouside of cases). I guess the way I had these two controller PCBs before with the much shorter ground bridges inside the common cases made the disturbance even less noticeable - to the point I thought it didn't do it at all.

So next thing to try is Fechter's RC filter idea I guess.

You know I have noticed this misfire issue with just a single motor running 44V and a 20A current limit.
There is a problem with how they handled stalling / low RPM in the software.

Could you expand on this? Are you saying that the controller software is a bit buggy when it comes to handling a stalled condition, and that you feel this "strugling stutter" even on your single hub bike? And do you mean it's worse at low voltage and low current limits, or just that it does it no matter what settings?

 

[ZapPat]

Would running a lm317 right off the battery pack to power throttle, and then just splitting the return line to both controllers work? It'd probably be pretty inefficient, because you would need to get the pack voltage under 37v for the lm317. Lotsa heat waste in resistors .

Wouldn't help tostino, because the problem is most likely taht the current spikes made by the stalled controller are changing the ground potential between the two controllers. That means that an analog signal common to the two of them, like the throttle, will appear to vary between controllers because of voltage difference created by the spike.

 

[mwkeefer]

Zap & Methods,

This may seem obvious but have you tried to set the current of both controllers to a rated current of 22a and a phase current of 45a? I think this "misfire" your talking about (once methods said he's seen this on a single controller install too) is actually an internal current limiter... I hit that a few times when trying to amp over 35 on the 9FET, until I smothered the shunt on that one... it pushes 58A now.

A quick reprogram to default limits could detect this... also be sure that regen is disabled, not jumped and fake indicate only and ebs level 0 are setup...

I won't ask if youve checked the throttle voltage range, I'm sure you have!

Looks like I will be joining you guys in another day or two, dual hub setup 26". guess I'm in for fun eh?

I saw you tied GND together inside then outside the case... Have you tried to link the MCU reset, vcc, gnd and clock lines? That would get both MCU running the same base levels and may handle the issue if it is a stall current situation.

Just my .02, guess I will get to try this myself soon = )_

-Mike