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

[DISH]

Thanks for the additional info!

Issues like this can be difficult to analyze as there can be minor wiring differences which can have major effects when it comes to ground loop issues. Your comments suggest that most of your problem was caused by PWM noise on the throttle control signals caused via the ground loop back to the battery.

Your argument is straight forward - not hard to follow at all.
In actuality - the worst cases I get is near freewheel and at very low motor loading - I am talking like 5 - 10A
At those kinds of currents with the size cabling I am running I should not be seeing volts of drop... maybe mV....

EXCELLENT observation and very helpful!!!

That would be the worst case situation as the PWM is active to hold off the motor speed and causing all kinds of spikes and noise on the common ground line.

Under those conditions your PEAK current drawn from the battery is still quite high but average current is low and that is what causes the noise to appear on the common ground loop. The throttle signal is not only sensitive to DC level shifts but noise as well and millivolts of level shift or noise riding on the DC throttle signal is enough to cause problems.

A very small amount of noise on the throttle control signal can get magnified as a very small change in throttle control signal causes the PWM signal to change which then gets fed back to the throttle control signal via the common ground loop which then causes more change in the throttle control signal! This creates a feedback condition where things can get really weird very quickly and is why it's so difficult to figure out what is going on.

I used the large 1.0 volt drop reference only to make things easier for discussion. I thought it would be easier to understand what I was talking about if I stuck to whole numbers (like 1 volt) rather than .001 or millivolts. Sorry if that misled the discussion as millivolts of noise or DC level shift can cause problems due to the feedback issue mentioned above.

The troubling thing is that this is not happening while one motor is pumping 100A and the other is freewheeling...

Once again a very helpful observation!

When the throttle is wide open PWM should be inactive meaning there is no PWM noise on the common ground between the controllers. The test you mentioned (100 A to one motor while other is freewheeling) suggests that most of your problem may be PWM noise on the throttle control signal and the simple RC filter that someone suggested early on should eliminate that, provided of course you do not also have a DC level shift problem going on at the same time you have a PWM noise problem. An RC filter will kill the noise but will not correct any DC level shift issues.

If this is the case, anything that can be done to keep the 5V rails equal and the 5V Grounds equal will help.

The 5 volt rails should already be pretty well isolated by the internal regulators and filter caps in the controllers. The 5 volt voltage level usually doesn't vary much from controller to controller unless of course there is something wrong with the regulator and in that case I think you would notice it running that particular controller by itself.

I am going to try bringing out a +5V 12AWG wire and a 12AWG ground tap - as close to the uC as possible.

I suspect that you will find that tying the grounds together with a VERY SHORT piece of HEAVY wire plus putting the cases of the two controllers together so that they are in electrical contact with one another will be a BIG help but you may still need the RC filters on the the throttle control lines. I don't think that tying the 5 volt lines together will help and in fact may be a bad idea as you could end up injecting the common ground loop noise directly into the 5 volt bus. The 5 volt bus should already be pretty well isolated due to the internal regulator and filter caps.

In my circuit I am bringing out 5V, GND, and Throttle from each controller and tieing them to the same potential at the Y point where the throttle is.

That's a good start but the wires going to the throttle are too small in diameter to have much effect on eliminating the common ground loop issue back to the battery where large currents are flowing.

 

[Arlo1]

i would prefer a Honda crf250r anyday of the week

soft cocked it and went back to hub motors...
Perhaps we can all pitch in and buy him a nice pink frock to wear
when he goes riding now

He already has a pink frock collection, each one is labled for the day of the week.

I agreed with everything except that letter "F" in the CRF250R... Surely that was a typo, and you meant to say CR250R. 2-stroke for life! 4-strokes on dirt are for the pink-frock crowd. I want to fear for my life everytime the powerband hits, and you just don't get that from bikes with the letter "F" in the name.

Your funny. Its like this luke I spent 5 years racing motocross and try to turn pro till I ran out of money and I had to work for a living. For the first 3 years I raced a 2 stroke and loved it I built my own race engines without cheating I have a record for one dyno in calgary for most Horse power from a 125 and I built that engine to have a brod power band in fact through the whole rev range It made more power! That was my favorite bike then the 4 strokes came and they had more power out of the crate! I road just one and 2 days later I owned one. You see I was stubborn as you but when the race rules alow a 4 stroke to be 2 times the engine displacement you have to ride it. Now I will never look back. Its all about having a better bike. Oh and me and a friend used to do 5 dolar holeshot races on our 125s we were the only 125s the rest were 250 two strokes and it was always me and my friend who won ALWAYS. And don't tell me about a hard hitting power band on a 250 2 stroke lol they almost dont have one now how about a cr60 theres a hard hitting power band!

Now back to the problem at hand My number one concern is the electric engine has to be submersable! Number two, liquid cooled just makes sense. Number three, Wye delta should be done for at least 2 speeds! I am at a very good position to help with this I work at a motorcycle wrecking yard and my boss whould love to help with this, we should be able to find a rolling chassis that will just need a motor. I don't care if we use 50 ah of 24s lipo It will be built to run for a good while.
Oh and I compared this to a four stroke not a 2 stroke because the 4 strokes are known for there torque and an electric bike whould have more torque!

 

[methods]

I am not getting any emails for any of the threads I post to
Something is wrong

-methods

 

[DISH]

I'm not either if that's of any help

 

[DISH]

I'm not either if that's of any help

And now all of a sudden all my posts appear TWICE

Notice that both have the same exact time stamp. I edited the second one just to see what would happen...

 

[methods]

I think there was a lag on the server last night
Other weird things were happening too.
Seems to be back on track now.

-methods

 

[ZapPat]

Some 2WD-on-ice testing news for those interested:

I tested my 2wd motocross-tire bike on some hard packed snow + ice the other day and it really rocks for grip!! I tested it on a hill on which I had just flipped my rear wheel drive norco bike on (ouch!) while driving up using moderate acceleration. Once the rear wheel started loosing grip it just continued pushing the rear towards the front, sending me into a sliding stop going sideways on the road.

I traded bikes with my friend who was driving my 2WD, and proceeded to do acceleration and braking tests on the same hill I just flipped on. The results were incredible!!! For one thing the 2WD bike has much more power which usually would mean being more prone to spining out, yet it accelerated much faster than the RWD while maintaining control. What happens is that when the rear wheel would start sliding out from under, the front wheel pulls forward and thus rectifies the bike's direction without the rider having noticed anything at all.

As for braking control comparison, I only had front disk brakes on the RWD norco so needless to say it was downright dangerous braking with it on the ice! The 2WD still only uses regen for it's braking, and it made for excellent handling while braking - no loss of control whatsoever. I was going back and forth on the icy patch on the road - accelerating, braking, accelerating, braking... It was surprising and fun! The inherant ABS-like behavior of the regen brakes is great on loose gravel and even ice it turns out!

Pat

 

[Affliction]

I've been running a 2wd bike for two winters now. Dual chrystalite 408's with 20A controllers and separate throttles.
At 48 volts it tears though any snowfall on my commute to work. Studded Swalbe tires help too :d
I previously had 1 throttle to two controllers and had this stuttering effect; this was not really a concern tho but control of drive traction was on icy surfaces. I bought a left twist throttle for the other bar and now have alot better control plus 2 totally separate drive systems for when 1 fails.
I read this entire thread and I'm impressed I wish I could do a double burnout
There is alot of input on trying to make only one throttle work for both hubs but on my experience this is actually detrimental to the fun and control a dual throttle setup can provide.

 

[methods]

Got an interesting PM...

Guy says that he was running two controllers - an Infineon 18 fet and an xlyte 18 fet (actually the same controller in two different boxes) with one throttle.
Claims that one controller (the infineon) started showing poor behavior after some time
It would cut out at 90% throttle, then 80, then 70, ... then 10%

He proposed that an over-voltage condition on the A/D of the Infineon trashed the A/D

Considering the above talk about the possibility of an OV condition on one controller given all the variables I am thinking this could just be the case.
Working toward that argument he was running a pair of 5303 motors and I imagine the two controllers must have had different current limits.

Sounds like a perfect storm to me.....

BUT -> This is speculation and lets not go hammering any nails in the dual controller single throttle coffin. I asked him some questions and this may pan out to just be something silly. I know for a fact that we can run 2 controllers and 1 throttle - it is just a matter of thinking about it hard enough and finding the simple solution.

-methods

 

[ZapPat]

Dual X5's/18FET controllers ---> Too bad he's having funny problems.

From your description of the problem, Methods, I don't think it's the same problem at all as I've seen on my 2WD. He might well have managed to fry one of his controller's throttle AD input with a large voltage spike, but I can't see it slowly reducing it's throttle response range before busting outright... :?

What's his ground wiring like? This is the most crucial part when using two throttles.

I'm considering modifying a hall throttle to have two sensors inside, each independant. User Affliction said that he actually prefers using two seperate throttles, but I really can't see myself trying to maintain good control of one throttle on each hand at the same time - they're already bad enough alone! I also think Methods tried it once, but didn't like it I think. I wonder why Affliction likes it this way more than only having one throttle? I didn't get the part about the 'icy surface' driving, but I guess you kinda have twice the control you had before over your no power to full power throttle range.

 

[Arlo1]

Ok so how about this.... Is it possible to just use the 5 volt power from one bord and feed it to the other 5 volt curcit on the other bord?
I think this should be the fix. which is done one of two ways both have the grounds linked from one bord to the other.
Option A dissable the 5 volt power supply on one bord and bring the 5volt in from the other bord so they match
Option B just simply run a wire from one bord to the other to link the 5 volt supplys.
If I understand this right the problem maybe that both bords have slightly different 5volt curcits and they proly vary as things go on. So matching the 5 volt curcits and the grounds should work. I think the ecu takes a reading from the throtle and references it to ground but if the other bord has a spike in the 5 volt curcit then it will feed that to the throtle line and it will make a funny reading.

 

[ZapPat]

Ok so how about this.... Is it possible to just use the 5 volt power from one bord and feed it to the other 5 volt curcit on the other bord?
I think this should be the fix. which is done one of two ways both have the grounds linked from one bord to the other.
Option A dissable the 5 volt power supply on one bord and bring the 5volt in from the other bord so they match
Option B just simply run a wire from one bord to the other to link the 5 volt supplys.
If I understand this right the problem maybe that both bords have slightly different 5volt curcits and they proly vary as things go on. So matching the 5 volt curcits and the grounds should work. I think the ecu takes a reading from the throtle and references it to ground but if the other bord has a spike in the 5 volt curcit then it will feed that to the throtle line and it will make a funny reading.

The problem is not the 5V supplies being of different values, but rather the grounds in each controller being pushed to different levels. This would not be a problem if we used one throttle for each controller, because each throttle would be free to follow the ground reference (ie 0V) in each controller. Now when using only one throttle, if there is a current spike in one controller that causes (lets say) a 1V difference between the controller ground levels, then one controller will see a throttle level that's very different from the other one - causing a stutter.

To make matters worse, the no-power to full-power throttle input range on these controllers can be quite small, specially with high power setups. So even a 0.5V difference on the controller's throttle inputs can easily turn into a huge power output difference.

 

[methods]

Two throttles may be cool for low power but it is dangerous for high power.
Hazardous.

You have a great idea Pat - 1 throttle two hall sensors. Beautiful solution. Eliminates 99% of the BS
If you implement it the naive way - by just stacking them - the 3-4mm offset could be corrected with a very small inline resistance.

I have a shipment of 20 throttles arriving this week. I will crack a couple different brands open and see which is best suited to the mod.

Thanks Pat for coming up with such a simple and eloquent solution...

-methods

 

[gogo]

The throttle sync issue seems like a good excuse to go to a cable and remote sensor box setup. These cheap ass plastic throttles seem like a weak link to me.

 

[ZapPat]

I do not know if I have read this thread correctly, but if we used (2) Hub motor's on a single ebike, give "about" the same autonomy of a single Hub motor because each of them are sharing the load, it's correct?

Then at 100 Volt 50 Amps for each motor's gives, better take off than a single one hub motor even if we use 100 Volt and 100 Amps on it. If it's true (2) X5 will never heat too much in this configuration.

Yes, two hubs can actually be more efficient than only one - but only when you are pumping more than a certain amount of current into them. And with X5's you will have to be asking a fair amount of torque from them before the 2WD comes out more efficient than a single hub. At 10kW I'm sure you will be a winner on efficiency if you go with a 2 X 5kW setup. High torque accelerations will be much more efficient, and much less heat will be produced in each motor (I would guess less than a quarter of the previous heat rise due to having only 1/4 of the I^2*R losses per hub!). But if you are just rolling along a flat road with a dual X5s at 40 km/h you won't be gaining anything for sure. You would eat up big hills though!

In this 2WD set up you are able to climb a sand hill that I single hub X5 motor are not able to do right?

You'll need good tires, but I bet you would have a great time on sand with a 2WD! I once found a small surface of sand while riding along a river and had so much fun doing donuts (tight circles) - it spits out sand from both tires! The gyroscopic effect effect from the front hub's spining mass makes for a very interesting steering effect when combined with a rear hub. I've found my dual 9C hub pretty hard on my arms on difficult off-road rides, but I got used to it pretty fast.

I'm just curious to know how your ebike react when turn with it on tight corner a mean like when we riding an ICE motocross? Is easy to turn or it's very hard?

This is pretty hard for me to say for sure because I've never riden a powerfull ICE motorbike, and don't even have a powerfull rear wheel drive ebike yet. For sure the gyroscope effect in the front hub makes the steering resist sudden changes in direction, but this can have it's advantages. I once was saved by this effect when I hit a hole in the road as I was riding down a hill without my hands on the handle bars. I just managed to grab at the handles as I hit the hole, but the front wheel had already turned 90 degrees into the hole - sideways. But like magic the wheel twisted right back towards the front with very little aid from me... saved me from a front flip onto the road at almost 30km/h! The el-crappo rim had such a huge warp in it that it didn't spin freely on the bike anymore, I had to stand on it to make it flat enough to be able to limp the bike home.



Let us know when you try your dual X5 setup, bikeraider! Come to think of it, you could use a lighter 9C on the front, just choose a close RPM/v caracteristic for the hubs. There will likely be a difference, but you could adjust one of the controller's speed settings to conpensate for the speed difference of the hubs. That might make a cool 2WD...

Pat

 

[methods]

The throttle sync issue seems like a good excuse to go to a cable and remote sensor box setup. These cheap ass plastic throttles seem like a weak link to me.

Being an electronics guy I place more faith in a magnet and a hall sensor than I do in an electromechanical device. The idea of pulling on a spring-loaded potentiometer just sounds hideous to me

The failure mode of the hall sensor throttle is well understood. If the spring or the hall fails inside of this cheap plastic throttle you can recover.

On a cable pull device, the failure mode can be catastrophic. If the spring fails the potentiometer can stay in the full throttle position. If the potentiometer fails it could apply any voltage to the throttle input. If the fasteners fail on either the handle or the box the throttle can be engaged. A stick or twig on the trail could also yank the throttle line as well (as has happened to me with brakes and gears)

-methods

 

[AussieJester]

Not being an 'electronics guy' i would be looking at a more mechanical way around the issue, i would be looking at gutting two lever type throttles, using one lever to control the internals of two..'piggy back' them if you follow my line of thought...would this not fix the issues?

KiM

 

[Toorbough ULL-Zeveigh]

linear taper coax stereo pot.
no ex-audiophiles on board?

 

[Affliction]

From your description of the problem, Methods, I don't think it's the same problem at all as I've seen on my 2WD. He might well have managed to fry one of his controller's throttle AD input with a large voltage spike, but I can't see it slowly reducing it's throttle response range before busting outright...

Connecting a single throttle to two controllers is just a recipe for disaster. I've blown throttle control on my own controllers doing this!
Not sure what happened but one controller fried a chip on the other and the fried one would no longer work without the throttle input from the other controller. Since I have gone to two independant throttles. Left and right half twist, The control soon becomes second nature.
Why try for one throttle anyway? It seems stupid to me now after getting used to having two. I did single throttle and it was ok but two is better!

 

[methods]

Like I said - maybe fine for a 36V 20A bike.

I almost killed myself with dual throttle.

-methods

 

[Rassy]

Not sure what happened but one controller fried a chip on the other and the fried one would no longer work without the throttle input from the other controller

This statement makes me think you may not have "fully" paralleled everything. I have been using one throttle to run two and three wheel drives and never experienced any problems. This includes both brushed and brushless hub motors. In all cases I applied the following rules:

1. The battery packs must all be the same and tied together in parallel. I.e., If you have a 48V 10AH pack for each motor/controller these packs need to be put together in parallel ahead of the controllers.

2. The motors/controllers/wheel diameters must all be the same.

3. All three throttle wires must be paralleled together.

If the above isn't observed, things will become unbalanced and too much current may try to flow through the throttle wires to balance the batteries, etc. Not being an electronic guy I have no idea what might really happen, but it probably wouldn't be good.

 

[wasp]

if it was me i would just use 2 thumb throttles and physically link them together so pushing one moves them both... but thats me

 

[Arlo1]

Thumb throtles are dangerous! I have one on a 100v 18 fet unlimited in a 20 inch bmx with x5304 and its basicly one of those circus rides the general people can't do without crashing but me the carny can

 

[methods]

I second that.

My dual throttle setup had a thumb control for the front wheel and twist for the rear.
To make it even more evil the thumb throttle was from Kelly and it would get stuck in the full blast position if you pushed down on it too hard.
Dont buy throttles from Kelly. Their controllers rock but those thumb throttles suck.

-methods

 

[gogo]

The throttle sync issue seems like a good excuse to go to a cable and remote sensor box setup. These cheap ass plastic throttles seem like a weak link to me.

Being an electronics guy I place more faith in a magnet and a hall sensor than I do in an electromechanical device. The idea of pulling on a spring-loaded potentiometer just sounds hideous to me

The failure mode of the hall sensor throttle is well understood. If the spring or the hall fails inside of this cheap plastic throttle you can recover.

On a cable pull device, the failure mode can be catastrophic. If the spring fails the potentiometer can stay in the full throttle position. If the potentiometer fails it could apply any voltage to the throttle input. If the fasteners fail on either the handle or the box the throttle can be engaged. A stick or twig on the trail could also yank the throttle line as well (as has happened to me with brakes and gears)

-methods

Mainly I'm pissed because I replaced a broken Currie half throttle and the replacement cracked right away. They are cheap enough that maybe I should just carry a spare. I wonder if the Magura is any sturdier.