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

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

Postby methods » Sun Dec 20, 2009 4:15 pm

SOLVED

A member asked me to help him put together a 2WD bike. This gave me an excuse to disassemble two 1/2 twist throttles and build them into one.

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These particular throttles are from Ebikes.ca. There are many types of hall throttle - this particular model is very nice. The hall slides right out and there is room to mount a second hall in tandem.

Tips:

* In the minimum throttle position the magnet actually rotates a little too far. This actually raises the minimum throttle voltage. Glue in a small spacer (small zip tie?) to offset the minimum voltage. (Picture 007)

* The hall sensors behave the same upside down - mount the second one upside down to make room for the wires.

* Mounting the second hall in tandem will result in a slightly lower reading. The closer you get the hall the smaller the delta. This delta can be corrected with a small inline resistor or left. I am going to leave the delta to bias power toward the rear wheel. At time zero - 2WD is really just RWD - the front wheel is totally unloaded - so applying equal power will result in nothing but lost traction. At WOT the the power will be equal. At cruising speeds the offset will help (I hope) to avoid interactions between the two motors. Most of the load should be on the rear motor. At any given time the rear motor will carry more load than the front (as it should, unless you like loss of traction on the front wheel)

* Grind away some of the hall mount to get the second hall closer

* Move the strain relief zips ties around for a better fit

Off voltage:
Primary: 813mV
Secondary: 926mV
Threshold: 1.2V

WOT voltage:
Primary: 3.56V
Secondary: 3.48V
Threshold: 3.14V

Bias: 5% toward the rear


Credit to the member who suggested this modification earlier.


There - I have laid another egg. This offsets the fact that I tend to ramble OT. :wink: Those that got bored and stopped following miss out. :mrgreen:

-methods
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby ZapPat » Mon Dec 21, 2009 9:42 am

Cool throttle job, Methods! I very am curious to see how it works out. Your last post seemed to be pointing at the halls sensors as the culprits (as you thought in the beginning I believe), so I was a bit surprised to see you do this.

I can see that we are actually looking at two seperate problems problems here, one that only shows up in dual motor setups, and one that is a small but slightly annoying bug in the controller itself. The annoying bug is what we see when the throttle is just around the current cruising speed of the bike, and shows up as a "thud" in the motor. You explain this bug as "If I hold the throttle at say - 10mph put pedal to around 11mph I get misfires".

However, you also say "Infineons are particularly sensitive to poor hall signal. If your hall cable is longer than 4' you get the same "POP POP POPOP" behavior as you get with dual controller." I have yet to see this problem myself, and I had a setup with a very long hall sensor cable from the rear hub, and I had even wrapped the excess lenght around the bike frame - so I had at least six feet of cable without problems.

Now, the dual hub problem shows up like this: block one wheel from spinning while lifting the other one off the ground to let it freewheel. As the blocked hub's controller tries to make it spin, it creates large current pulses on the battery input. This creates "thuds" in the other (freely turning) motor, and does it worse the more throttle you give it. The controller will do this until it decides to cut off the motor altogether. The problem with this is that at low speeds and high torque demand (like right at startup or during slow trail riding), this same problem appears, making random but noticeable "thuds" in one of the hubs. It's not really a huge problem, but an annoyance. Anyways, your dual hall sensor throttle mod I believe will eliminate this problem (but will do nothing for the other real controller bug).

Your trike looks sooooooo fun to ride, I want one!!!! And all that space for batteries, front like you did and behind the seat even if need be. I just finished building my first 6p12s Lipo pack, and just barely managed to fit them into the bike's triangle. It is on my dual 9C hub, 26" road bike that I want to have long range with, so the 1300Wh should get me at least 50km without pedaling at ~40km/h. I'm hoping that it will help much with the winter roads I have to cope with...
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby methods » Mon Dec 21, 2009 11:07 am

I agree with everything stated above.

As far as my band-aid solution - instead of solving the real problem - I could not agree more. I did the band-aid just to get the show on the road but I think we really need to understand the real problem. Hopefully I will have some time next week as I have a week off work.

Enjoy your new 1.3KW pack
Best part is that you will be way above nominal for most all of your ride.

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

Postby auraslip » Fri Aug 26, 2011 3:09 pm

Couldn't you just use a separate 5v dc-dc to power the throttle?
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby Arlo1 » Fri Aug 26, 2011 3:37 pm

auraslip wrote:Couldn't you just use a separate 5v dc-dc to power the throttle?

Wow talk about a resurected thread! I think fetcher pointed out a way to do it.... I think you tie the 5v+ and signal together on each controller then leve the negatives seprate but I will have to dig to find this....
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby methods » Fri Aug 26, 2011 3:49 pm

All of those methods equaled fail when I tried. Too much noise.... An isolated DC-DC wont work because you have to tie the grounds together anyway so... it does not buy you anything.

The best solution IMHO is to build the double-hall throttle. It is the natural solution and builds in slightly less power to the front hub.

All of this could change too with the newer boards / algo's. Someone should try :twisted:

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

Postby auraslip » Fri Aug 26, 2011 4:02 pm

The best solution IMHO is to build the double-hall throttle. It is the natural solution and builds in slightly less power to the front hub.


That would be important! I was thinking of a way to limit the throttle to the front hub at starts anyways. Keep the front wheel from just spinning (also it'd reduce the need for giant torque arms) This would kill two birds with one stone. Probably the smoothest way to do it too. Just wish it worked with a magura.

XLYTE has a two motor controller out. Probably could just reverse engineer the circuit on that to figure it out?
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby methods » Fri Aug 26, 2011 5:00 pm

JozzTek converts Magura throttles to hall output IIRC. I dont see any reason they could not do two sensors instead of 1 - or you could do it. I like Magura throttles but a physical pot controlling 40KW or 50KW is really dangerous... A hall sensor with a magnet should last forever. Sounds safer to me.

http://www.jozztek.com/shop/en/throttles/23-british-throttle.html

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

Postby liveforphysics » Fri Aug 26, 2011 6:50 pm

This reminds me of something funny. The Sevcon controller manual calls out an "isolated double sensor throttle" for redundancy in the event some system fails, it only uses the lower value of the two throttle input readings.

We asked them, hey! Where do I find one of these???? They said, "umm... they make one in a foot pedal for fork-lifts... we've never seen any for a motorcycle... :-)"
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby auraslip » Fri Aug 26, 2011 8:08 pm

Yeah. I defiantly wouldn't want to be in a warehouse the day a hall sensor fails on a fork lift and sends pallets stacked to the roof flying everywhere. Very dangerous. Very big liability.

So when will high powered electric motorcycles get these?

WRT to the hall sensor magura: 130 pounds! SHIT.

JRH said somewhere that magura is either interested or actually producing a hall sensor based throttle in the future. Would be a nice day. Maybe someone can convince them to make one with dual halls to be used with two controllers or as a safety feature?
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby amberwolf » Fri Aug 26, 2011 11:09 pm

Would another possible solution to the double controller / single throttle problem be to run the hall to a pair of op-amps (or transistor amps) for tuning the gain to each controller, and then the output of those to separate analog-output optocouplers, or isolated instrumentation amplifiers (if such exist for this purpose), and then to each controller?

Yes, it's probably more work than modding a throttle for dual halls, but for those with no mechanical skills at the latter, the electronic splitter might still be within their abilities to wire up.

I guess the key would be to work out the circuit and test it before setting it up on the bike for that power-blasting test ride. ;)
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby voicecoils » Sat Aug 27, 2011 7:52 am

liveforphysics wrote:This reminds me of something funny. The Sevcon controller manual calls out an "isolated double sensor throttle" for redundancy in the event some system fails, it only uses the lower value of the two throttle input readings.

We asked them, hey! Where do I find one of these???? They said, "umm... they make one in a foot pedal for fork-lifts... we've never seen any for a motorcycle... :-)"


This is the dual hall foot throttle they talk about: http://www.evsource.com/tls_throttle.php

You could always have a conventional cable twist throttle operate a modified foot throttle for an excessively complicated system. You gain a hall sensor but add some additional failure points by adding the mechanical cable linkage. :lol:

JozzTek's throttle does look nice & worth considering for a high powered electric motorcycle for sure.
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby GrayKard » Sat Aug 27, 2011 3:51 pm

The throttle I modified with dual halls is still working fine after a year of hard use. Currently I am only using one of them as I only have a DD rear hub installed on the bike.

It was very easy to add the second hall and I'll do the same again if I build another 2wd bike.

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

Postby Jozzer » Sun Aug 28, 2011 7:16 am

That's not a magura we have on site, but a handmade solid aluminium throttle, hence the price. We're currently looking at ways to get this machined in bulk to cut costs. I'm not sure how easy it would be to fit with twin sensors, since we have the sensor fitted to the end of a bolt, so it can be changed without the need to strip the whole thing down.
We also offer a choice of spring strenghts and operating range (1/8 turn as standard). Output is full range, 0.05v-4.95v..
For dual Kelly controllers on one throttle, we just tied gnd from both throttles and used just one controllers 5v supply to power them, this worked out well..

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

Postby Arlo1 » Sun Aug 28, 2011 9:13 am

So last night on my bmx with 24s 2p lipo and X5 and a 24fet running ~180 amps peak (detuned a bit for less waste) I was ripping and hit the railway tracks then my throttle fet funny and my bike slowed down I twisted off then on and it was ok for a bit then nothing again so I let off and wham it went full throttle.... I have ebrakes thank god and used them to keep the controller shut off till I pulled over and found the cheep plastic housing was busted so the magnet was spinning away from the hall in both directions! I carefully road home but man I now understand we need something with a fail safe!
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby methods » Sun Aug 28, 2011 6:43 pm

Jozzer wrote: For dual Kelly controllers on one throttle, we just tied gnd from both throttles and used just one controllers 5v supply to power them, this worked out well..

Jozz


IIRC the Kelly of that power range has optically isolated inputs doesn't it? Even if it doesn't, I think the problem we are seeing with these infineons has to do with the firmware. It is not the best.


Arlo1 wrote:So last night on my bmx with 24s 2p lipo and X5 and a 24fet running ~180 amps peak (detuned a bit for less waste) I was ripping and hit the railway tracks then my throttle fet funny and my bike slowed down I twisted off then on and it was ok for a bit then nothing again so I let off and wham it went full throttle.... I have ebrakes thank god and used them to keep the controller shut off till I pulled over and found the cheep plastic housing was busted so the magnet was spinning away from the hall in both directions! I carefully road home but man I now understand we need something with a fail safe!


This happened on my KMX trike. I "pulled up" too hard on the throttle which caused the plastic grip to pop out, release the spring, and then pop back down. The throttle was then free to slide back and forth hammering full throttle. The 20A ebike guys may not understand... but anyone who has built a monster and had it get away from them sure does :shock:

I was once walking my bike through the living room past my mother in law when I accidentally blipped the throttle. It climbed all the way up my front door and bounced the front tire against the ceiling and left a burnout on the floor and door. Freaked her the hell out :P I keep the bike turned off now until I am on top of it :wink:

Another night we were prepping one of Steve's bikes for the TTXGP... We had just finished and the rider was going to test it out. She had NEVER ridden an electric before and she clearly had no idea how hard they kick off the line. (this is a full size race bike with dual Agni and 80Ah Lipo, not a bicycle) The controller was on and everything was ready to go but due to a bug in the Kelly firmware it was locked up. Ok - that was not such a big problem... the problem was that she had the bike pointed at a group of us, she was sitting all the way back on the seat, back straight, and she was rolling the throttle all the way up and down, back and forth saying "it doesn't work". OMG - I was waiting for that bike to explode out from underneath her... The Kelly has a "high pedal lockout" but that only applies on powerup. If the problem had been a loose connection or something like that and the controller had kicked on while at full throttle. Pfffftttt.... what a mess.


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

Postby bobale » Sun Aug 28, 2011 7:07 pm

methods wrote:The 20A ebike guys may not understand...

methods wrote:I was once walking my bike through the living room past my mother in law when I accidentally blipped the throttle.

Well I managed to make a damage with a lot less than 20A. I've just connected the battery, and blipped the throttle ever so gently to see did it power up, but my hand was wet and bike managed to run away from me and go clean through a bathroom window (which just came from a glass shop) which happend to be propped up the wall 5 feet in front of the bike :D.
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby methods » Sun Aug 28, 2011 7:19 pm

Good Job :mrgreen:

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

Postby bobale » Sun Aug 28, 2011 7:33 pm

Oh yes, about your bike. I've just seen video on second page. Holy smokes, that thing accelerates like it's being shot out of a slingshot. :shock:
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby Jozzer » Sun Aug 28, 2011 7:42 pm

I had exactly the same plastic throttle failure once a few years back, also on a KMX, though fortionatly only with about 5kw of power. I wouldn't consider using one on a motorcycle except in emergency.

This much power is really bordering on needing a contactor and easily reachable kill switch tbh, however safe you make the throttle, one short in the right place in your throttle cable wiring and your controller will see WOT. E-brake is the next best thing
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Re: 20KW 2WD having misfires (but can do a double burnout)

Postby texaspyro » Mon Aug 29, 2011 1:06 pm

liveforphysics wrote:The Sevcon controller manual calls out an "isolated double sensor throttle" for redundancy in the event some system fails, it only uses the lower value of the two throttle input readings.


The best dual sensor throttles have the two sensors outputting differential type signals... one goes up as the other goes down. If the two values do not agree mathematically you know there is a fault. Having both sensor signals move in the same direction can mask shorted wiring faults, etc. And for the real paranoid, you want the two signals to be generated by different technologies (like a pot and hall sensor).
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