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

[no mods]

I don't know if if caps would fix it.. Wouldn't there be more signal descripency upon WOT vs partial throttle if it was current related? Caps might work if the issue was present under WOT but I think he mentioned the problem was @ lower rates. If I misunderstood your post fetch my bad. I'm eating lunch writing a workout reading endless @ a 7pt font on a BB.

 

[bigmoose]

Meth I'm impressed again! Oh, as for the throttle, connect it to Controller A, also buffer it. Feed the buffered signal into a "linear" opto isolator. Power the buffer from Controller A's power to the throttle. You may have to put a gain stage after the now isolated signal to get the span right for Controller B. Power this gain stage from what would have been the power and ground supply to the throttle for Controller B. This will open up the ground loop. Sort of like the problem we had 20 years ago extending an RS232 between buildings with large loads in them. "Local" grounds were shall we say, more than a few volts "different".

 

[methods]

Thanks for the help Fechter! We will implement the suggestions and check back in.

I am totally excited -> I finally found some V-brake bosses and welded them to my fork.
Why the hell did it take me so long :?



This is HUGE!!!!
To celebrate - I hit a new record: 50mph sustained at only 18A

ok, ok - 18A per controller.... and... at 91V... but!

I had not done a top speed run yet due to raw fear
I roped that thing out to 50mph sitting straight up in the seat.
Voltage steady at 91V.
Current steady at 18A per controller
50mph steady for almost a minute - 3.2KW

Want to know the best part???
Motors were not even warm.
Ok - they were warm - but I am used to them being Smoking Hot!
I would have called these 80F - 90F

Today is another fine day.

Now back to the problems:

Another 2WD problem -> When using separate throttles with the 18 fet controllers, if I barely crack the rear throttle and I exercise the front throttle the rear will start to act up. I believe this is inherent in the design as I *think* I may remember this happening with my old setup though it is definitely worse now. I think Pat has experienced something similar?

Also - Pat or I need to measure the voltage at the input when 1 throttle runs two controllers. I would swear that now that I have 2 throttles the bike has more poop.
The mid-range acceleration is truly close to "too much" for this frame. My ass slides off the seat, my hands grope for purchase on the bars, my a$$hole puckers up...

I need to swap the handlebars for something that is meant for speed. I also need to fix the damn seat that keeps bending back under acceleration.

-methods (edit to fix spelling)

 

[methods]

Oh, as for the throttle, connect it to Controller A, also buffer it. .....

Thanks BigMoose :wink:

You -> Always providing an elegant, well thought out, and correct solution
Me -> Always finding some hack way to do it lazy and Ghetto

-methods

 

[bigmoose]

^^ That's why you get things done, and I just write reports! for you; for me

 

[Arlo1]

Thats awesome that you total system is using about 2.2 hp to cruise at 50mph Thats alot less then a motorcycle and even more less then a car which is ~20-25 hp with a gas engine! Cant wait to see the top speed! Let me know if you need a test pilot!

 

[methods]

I am afraid I have hit the top speed for this KV combo.
Those motors will draw 100A loaded down...
If they are only drawing 18A each I am confident I have hit the wind limit.

My only choice now is to swap the motors for higher KV or run a booster pack.
I have had bad luck with voltages over 100.8 so that is out...

I am in the process of ordering (10) 10x6 wind rear 9C motors (these I have now are 9x7) and a bunch of other stuff. When they come in I will build up one of those and let er rip.

(btw: I am going to offer kits with the 10x6 wind rear 9C in a 26" wheel, CA, throttle, torque arms, and either a 6 fet or 18 fet controller soon. Price will be comparable to other kits but I will offer free shipping and 4110 modded controllers. This will be a "Cheapskate overbooster special" with the "End of the driveway warranty" on the motor :wink: )

-methods

 

[ZapPat]

Also - Pat or I need to measure the voltage at the input when 1 throttle runs two controllers. I would swear that now that I have 2 throttles the bike has more poop.
The mid-range acceleration is truly close to "too much" for this frame. My ass slides off the seat, my hands grope for purchase on the bars, my a$$hole puckers up...

I checked this yesterday while runing both throttles, and the controllers start to react at about 1.3V and WOT (max) is at about 3.4V. The throttle itself outputs 0.4V to over 4V, but the controller does not use the full range. The normal low-frequency signal from the throttle looks OK, so I'll have to try Fechter's simple RC filter mod (thanks Richard!) to see if it might be some high frequency spikes in the throttle line that are causing the havoc. I would like to connect it up to the scope, but only if this mod doesn't solve the problem. Bigmoose's suggestion of opto-isolation would work (thanks Bigmoose), but it would take too many parts and design time for my liking... If it ends up requiring this type of isolation then I will just wait 'till my own controller is done and stack two side by side for a real good 2wd setup (with other 2wd firmware based improvements too eventually). The 2WD version would roughly measure 4.5"X7"X2" - how does that compare to one 18FET ecrazyman anyways? It would only have 12FETs per controller (24 for the 2WD version), but I am certain that even with this I will get at least as good performance as the 18FET ecrazymans (the thermal and electrical design is *very* different).

Another 2WD problem -> When using separate throttles with the 18 fet controllers, if I barely crack the rear throttle and I exercise the front throttle the rear will start to act up. I believe this is inherent in the design as I *think* I may remember this happening with my old setup though it is definitely worse now. I think Pat has experienced something similar?

I have an "old" 12 FET infinion that does a very annoying "rata-tat-tat" (like sequence misfiring or something) anytime I have it on minimum throttle setting, and no matter which speed I'm going at. I just avoid minimum throttle setting when using this controller. It does it alone BTW, doesn't even need feedback junk from a sibling controller to do it.

As for the problem you describe above with your two throttle 2wd setup, it's not quite the same as mine unless you were blocking your front wheel front from spining during the test you describe (like your previous single throttle test). However it does kinda sound just like the initial problem you were describing a few days ago, where you had to always be 'rolling' your throttle for it not to act up... but I'm just saying this from memory of that post. If yours is still doing the same thing with two throttles as with one, there must be some feedback happening elsewhere in the system - maybe the main power leads or the logic power supply? My own common ground point is closer to the two controllers, and also I'm not pulling the huge currents you are, so my ride's symptoms may not be as severe as yours. One thing I did observe over a week ago though on my own one throttle 2wd setup though: If I cranked the throttle full open from standstill the controllers seemed to very often just cut off. It's as though the controllers had detected some fault and shut down the outputs. Droping the throttle would reset the fault. Starting up just a little bit lighter on the throttle, then going WOT right after that would avoid triping this fault mecanism. :?

Working with "black boxes" is annoying sometimes - I better get back to my own "semi-transparent box" design now!

 

[methods]

Just to be clear as to where I am:

Running 2 throttles on 2 controllers
The original problem of misfires has vanished. The controllers appear to work fine together.
There is still the standard problem inherent in the design - where just cracking the throttle causes misfires.

I am glad Pat and I are on the same page. We can work through these problems twice as fast.

Pat -> Re your experience with trying to take off at full speed:

Assuming your batteries are not dipping below LVC - it is most likely the protection circuitry in the controller. If you bump up the current limit another 30% my guess is that it will go away. With basically no current limit, if I try to launch at full throttle there are between 1 and 3 cogs then it explodes. Almost instantaneous - fast enough to work around. The Kelly controller on the other hand will explode off the line violently - but that is no necessarily useful for anything except getting hurt. Anyhow, I think the current is just jumping too far too fast and the control circuitry is cutting you off. Bump that current limit

-methods

 

[kfong]

Wow, I had dismissed 2wd as a possibility. It looked like it would overcomplicate a build, but after seeing your results. I like the idea! I won’t be looking at your power levels but the thought of a quiet hub motor with lots of traction in the trails has me wanting a similar setup, even if I have to stick to a steel non-suspension fork. Thanks for pushing the limits.

 

[Doctorbass]

( did you said previously you was not interested by speed??? )


Methods, What is the no load speed of the wheels?

I wonder cause you mentioned that you think you are limited by the kv.

I know my no load speed and my loaded speed and the ratio is important.

for my drag speed record, i had a motor at 145kmh no load and i've reached 94.4km/h on the drag lane with a front wind of 24km/h

let say 94.4 + 20km/h(wind effect) =114.4km/h speed no wind on road
if the no load speed is 145km/h then the difference is 27%

What is the differrence you obtained?

Doc

 

[methods]

I have to go home and measure again to be sure. Something around 65mph is the no load speed off the top of my head.
15mph difference - so about a 23% change (depending on how you calculate it)

It should be noted though that this is all subjective.
If I were to tuck down I could probably hit 52mph or faster.
I am also running big soft knobby tires... running 70psi on street tires would make a small difference.
If my pack were to droop a little or be slightly stiffer it would change by a few mph

I always thought the rule of thumb was to knock the freewheel speed down by 20% to get a good estimate.

Either way - 50mph is as fast as anyone should go on a bike without body armor - too fast really.

-methods

 

[John in CR]

Methods,

Find yourself a steel dual suspension bike and stretch it at least 6 or 8". The smallest bumps are killers about 30mph or so with a hardtail. Stretching the wheelbase and lowering the seat makes a bike feel just fine at 50 or more, though you'll probably want to slacken the head tube angle to be more like a motorcycle too.

Too bad I haven't started importing the motors I use yet. I think they're just what you need with the heavy duty great quality construction, and the no load 16 rpm/volt windings.

John

 

[GGoodrum]

I think his Electra already has a bit longer wheelbase, which I agree makes a big difference at speeds above 40 mph. I did a mountain bike conversion, for a friend, but being that upright at 40 was too scary for me. My Electra Townies have a much longer wheelbase, and you sit lower, so even at 45 it is not so bad.

As for suspension, my friend's mountain bike had a full front and rear suspension setup, but it still rode way too rough for me. Instead, what I did was put on some Schwalbe "Fat Frank" balloon tires, which only get inflated to about 30 PSI. It rides smooth as silk now.

-- Gary

 

[methods]

Project Mayhem is built on a Kona Stinky Primo with 8" suspension front and rear.
The wheelbase is short but it rides like a dream.
This will be the platform for my AstroBooster.

The Electra is just a good, simple bike for testing. Something I can scratch up, weld to, crash...

I am not so worried about feeling comfortable at 60MPH -> I am more worried about how I will feel if I crash.
50 is fast enough.

-methods

 

[MitchJi]

Hi,

Project Mayhem is built on a Kona Stinky Primo with 8" suspension front and rear.
The wheelbase is short but it rides like a dream.

-methods

Handles well and feels good at 35 or 40 mph?

 

[methods]

Hi,
Handles well and feels good at 35 or 40 mph?

The Projet Mayhem version only went around 42mph
Handled fine. Very responsive though - requires both hands on the bars.

When I had the cyclone on there I hit 55mph on a slight downhill
(contested as I never did get a video - system self-destructed)
I recall being scared - but I think I was more scared of the cops than crashing.

So yea, the Kona stinky is a great bike around 35 - 40mph...
The frame is a Medium and I am 6'4" so it is already too small for me
As I understand it - the Kona Stinky is a small bike in general.

-methods

 

[steveo]

I have to go home and measure again to be sure. Something around 65mph is the no load speed off the top of my head.
15mph difference - so about a 23% change (depending on how you calculate it)

It should be noted though that this is all subjective.
If I were to tuck down I could probably hit 52mph or faster.
I am also running big soft knobby tires... running 70psi on street tires would make a small difference.
If my pack were to droop a little or be slightly stiffer it would change by a few mph

I always thought the rule of thumb was to knock the freewheel speed down by 20% to get a good estimate.

Either way - 50mph is as fast as anyone should go on a bike without body armor - too fast really.

-methods

You should be rollin' with this bad boy .. "HEyyyyy LAdies""

-steveo

 

[aaronski]

(btw: I am going to offer kits with the 10x6 wind rear 9C in a 26" wheel, CA, throttle, torque arms, and either a 6 fet or 18 fet controller soon. Price will be comparable to other kits but I will offer free shipping and 4110 modded controllers. This will be a "Cheapskate overbooster special" with the "End of the driveway warranty" on the motor :wink: )

-methods

And I just bought my new one. D'oh! My wife's going to kill me when I get another one...

 

[ZapPat]

Running 2 throttles on 2 controllers
The original problem of misfires has vanished. The controllers appear to work fine together.
There is still the standard problem inherent in the design - where just cracking the throttle causes misfires.

I am glad Pat and I are on the same page. We can work through these problems twice as fast.

Pat -> Re your experience with trying to take off at full speed:

Assuming your batteries are not dipping below LVC - it is most likely the protection circuitry in the controller. If you bump up the current limit another 30% my guess is that it will go away. With basically no current limit, if I try to launch at full throttle there are between 1 and 3 cogs then it explodes. Almost instantaneous - fast enough to work around. The Kelly controller on the other hand will explode off the line violently - but that is no necessarily useful for anything except getting hurt. Anyhow, I think the current is just jumping too far too fast and the control circuitry is cutting you off. Bump that current limit

-methods

Thanks for those details, Methods, it helps make sense of some things I've observed. So your two 18FET controllers setup gives you this kind of behavior during a brutal startup... that's good to know. I agree with you that this sucks as normal behavior, wish it was more like the way you describe the way the kellys work.

My setup consists of two 6FET ecrayman controllers that I bought as unwired, FETless unmounted PCBs + hardware. I added 4110's, beefed up the battery buses, added extra ceramic caps along the bus and used nice silicone wires. I did not change the 63V caps and so I am limited right now to lower voltages which is OK for me most of the time. This might change if I order some slow and torquy 10X6 hubs from Jason (e-bikekit.com) - did you chage anything else but the caps when you moded your own 6FET box? (other than the logic supply too of course)

As for your current limit suggestion, they are already giving about 35-40A each so I'll try to up that a bit. I'll use solder instead of programming since I think the single shunts will not like seeing 50A+ without some reduction in resistance. I am using 3P12S Lipo's, so sag is really not the issue I'm sure.

Sorry for this slow response, my mom has been having some health issues so I've been distracted lately. I haven't even checked out the throttle signals on the scope yet, nor tried Fechter's simple RC filter suggestion. I also bought a nice norco downhill bike last week and of course I've already started turning it into an electric beast. No way am I pusing that thing UP any mountains!!!

 

[methods]

This might change if I order some slow and torquy 10X6 hubs from Jason (e-bikekit.com) - did you chage anything else but the caps when you moded your own 6FET box? (other than the logic supply too of course)

On the 6 fet boxes I replaced the cables with 10AWG Coper, used IRFB4110's, Soldered the shunt down to around 500uOhms or 750uOhms (IIRC), beefed the copper traces up considerably, and left the rest.
(of course I dumped that shit-rat wiring he includes and used my own pigtails )
I added no capacitors - mine came with 65V and I run 12S lipo.
Since then I sent the controller to Bob at AstroFlight.

Oh yea _ I added a programming harness too.

I programmed it to 50A for a few weeks then 65A
On a hot day the case will get warm at 65A

-methods

 

[ZapPat]

This might change if I order some slow and torquy 10X6 hubs from Jason (e-bikekit.com) - did you chage anything else but the caps when you moded your own 6FET box? (other than the logic supply too of course)

On the 6 fet boxes I replaced the cables with 10AWG Coper, used IRFB4110's, Soldered the shunt down to around 500uOhms or 750uOhms (IIRC), beefed the copper traces up considerably, and left the rest.
(of course I dumped that shit-rat wiring he includes and used my own pigtails )
I added no capacitors - mine came with 65V and I run 12S lipo.
Since then I sent the controller to Bob at AstroFlight.

Oh yea _ I added a programming harness too.

I programmed it to 50A for a few weeks then 65A
On a hot day the case will get warm at 65A

-methods

10AWG wire? I barely managed to pass the 14AWG through the small phase and batt pads without loosing strands. I run the 14awg to just out of the case then splice it out to some 10. And I tought for some reason that you were runing that thing higher than 12s. I also read in another thread that you found out that the 6fet 116 controllers are soft-start, it may explain the way my latest rear wheel setup acts a bit lame on the throttle.

In the last 6fet I just assembled I added some lead free solder to the shunt, wondering how much more conductive the lead free solder is (it has copper and silver after all...). I left the programming the same as for the 2wd bike using unsoldered stock shunts, which gave me 90A peak readings on the CA including both controllers (~75A readable on screen). It turns out I got 110A peak readings on the CA with only the one soldered controller (~80A readable on screen). This would mean that the soldered shunt is *much* lower in resistance than the stock shunt, so I'll have to lower the programming a bit to compensate. Mine is getting quite hot after only a few accelerations going around the house --> not good! Note to self: Use Method's neat icharger foam cutter idea to find out the shunt's real values...

I find that a 1wd bike with a controller at double current settings is less responsive than a 2wd bike using two half power controllers. I can see a few technical reasons why this would be true, but I wonder by how much under different circumstances? The 2wd excels at higher current demand applications, becoming more efficient and torque providing when accelerating or climbing hills. Of course traction is great, but appropriate power distribution between the front and rear wheels would still help much. Both drive power and regen braking power distribution could be taken care of automaticaly by the motor contoller's MCU(s). Altough some here seem sceptical about the usefullness of regen braking, but I find it a very pleasurable and safety-enhancing feature on an ebike, specialy one using non disk brakes. Of course if you don't stop often and don't bike in hilly places, it's of limited use. For trail and mountain riding it's a must in my opinion.

I'll have to take and post some photos of my quickly accumulating bikes sometime (it's addictive), incuding the two 2wd's.

 

[ZapPat]

Success!!

Here's my solution to the "one throttle on two controllers" problem. Sorry for not taking any inside pictures, but it's a pretty simple mod. I can now go wide open throttle at takeoff without having one of the controllers cutoff.


I just made two hefty connections between the two board's grounds, right where the ground wires enter the boards. Since they are back to back as you can see, the shunts end up on either side of the board. The PCB's end up having a weird angle relative to each other, or else the cases will not fit together smoothly. I tried it out yesterday on my second 2WD ebike build and had fun on some *very* soft and difficult to drive trail surfaces, but was limited by the mini Lipo pack I was using for the tests (1p12s - 5Ah). Here's the frankenbeast:


The bike is made from an old 24" frame (found at the junkyard), a 26" front suspension fork (1$ at garage sale), two nine continent hubs in 20" rims mounted with two 16"X3.00" motocross tires. Oh... and *no* brakes! It only uses the regen brakes to slow down (works well so far even on some pretty steep inclines). And of course it uses a good old wood 2"X3" as a footrest. These tires have CRAZY grip compared to any bike tires I've ever seen, but they weight about 7 pounds each, which is half the weight of each motor/rim. That makes for about 23lbs per wheel, so this thing wants to really stay on it's feet with all that low down weight.

On the second run I managed to rip the back valve out of the tube, I suspect from excess torque combined with the vaseline I used to mount the tires to the rims. I have now been told to use dish soap to mount the tires instead of vaseline which I will try when replacing the tube in a few days.

I'll might post another photo of this odd 2WD bike when I'm done mounting a more appropriate 3p12s lipo pack inside the frame and have finished cleaning up the wiring.

 

[Doctorbass]

Success!!

Here's my solution to the "one throttle on two controllers" problem. Sorry for not taking any inside pictures, but it's a pretty simple mod. I can now go wide open throttle at takeoff without having one of the controllers cutoff.

View attachment 1
I just made two hefty connections between the two board's grounds, right where the ground wires enter the boards. Since they are back to back as you can see, the shunts end up on either side of the board. The PCB's end up having a weird angle relative to each other, or else the cases will not fit together smoothly. I tried it out yesterday on my second 2WD ebike build and had fun on some *very* soft and difficult to drive trail surfaces, but was limited by the mini Lipo pack I was using for the tests (1p12s - 5Ah). Here's the frankenbeast:


The bike is made from an old 24" frame (found at the junkyard), a 26" front suspension fork (1$ at garage sale), two nine continent hubs in 20" rims mounted with two 16"X3.00" motocross tires. Oh... and *no* brakes! It only uses the regen brakes to slow down (works well so far even on some pretty steep inclines). And of course it uses a good old wood 2"X3" as a footrest. These tires have CRAZY grip compared to any bike tires I've ever seen, but they weight about 7 pounds each, which is half the weight of each motor/rim. That makes for about 23lbs per wheel, so this thing wants to really stay on it's feet with all that low down weight.

On the second run I managed to rip the back valve out of the tube, I suspect from excess torque combined with the vaseline I used to mount the tires to the rims. I have now been told to use dish soap to mount the tires instead of vaseline which I will try when replacing the tube in a few days.

I'll might post another photo of this odd 2WD bike when I'm done mounting a more appropriate 3p12s lipo pack inside the frame and have finished cleaning up the wiring.

Great Work!!

2wd seems more and more attractive built!! do you hear intense tire noise when riding?

Doc

 

[fechter]

Success!!

Here's my solution to the "one throttle on two controllers" problem. Sorry for not taking any inside pictures, but it's a pretty simple mod. I can now go wide open throttle at takeoff without having one of the controllers cutoff.

Interesting. So it was a ground loop problem. There may be other ways to deal with that, but don't argue with success.

That bike looks like an absolute beast

I might suggest some actual brakes and maybe something nicer for the footpegs :wink: