Rebuilt kids electric cross to 3000w

Dixonk

100 mW
Joined
May 7, 2022
Messages
47
Hi there, new to the forums and apologize in advance if this is the wrong section of the forums to ask a question.
To make a long story shorter
I bought a 500w 24v electric cross for my son and after the first hour literally he out grew the tiny power it had, q few days later he got bored but expressed the want to continue riding so my father had this idea. Why not take the escooter 36v 1000w motor and slap it on the bike?
He gave me the motor and I bought a 36v lithium battery and rebuilt it with a bms more suitable, all said and done. It went better. Couple of weeks later he really wanted to take it to next level so we went to a motocross club to ride on genuine tracks, but the low power wasnt enough, so I ordered a 3000w 72v kit brushless kit.
Had to do some fab work to fit the motor and controller (which grew in size drastically, well.. only thr controller really..) in the frame.
All said and done.. built a new 72v battery and wired everything.

Test ran it today and its just insane, slight touch on the throttle the whole bike just does a wheelie..

I didnt think 3000w would have this kind of power.. without changing motor and stuff which involves a fair bit of work, can I somehow easily limit the power of the motor to say 1500w/2000w or regulate the volts going to the controller/motor?

Im at a loss, Ive watched videos of people riding ebikes with 8/12kw and thinking 3kw would be somewhat equal to a 65/80cc cross but me sitting on this bike Im lifted off the ground, theres no way I can put my son on this thing.

Any ideas how to limit this thing??
Best regards
 
Without pics or links to sale pages for items you have, it's tough to give any specific suggestions, so some general ideas:

If it is a chaindrive to the rear wheel, change the sprocket ratio for more speed at the rear wheel but less torque. Bigger rear sprocket is more torque, bigger front is more speed.

Or change the current limit of the controller (reducing the power of the system). If it's programmable, you can do it in it's settings. (if you don't already have the stuff to program it coming with it, or offered on the same page it was bought from, it probably isn't programmable)

If it's not programmable, you can reduce the current limit by desoldering one of the battery current shunts, if it has more than one. If it has two, removing one cuts current in half. If it has three, by one third. Etc. If it only has one, you can't do it this way (there are other ways...but they're not all as easily reversible as this mod is).
 
I forgot about linking what I have, good call. Thank you for the reminder.
Its this kit
https://www.amazon.com/VEVOR-Electric-Brushless-Motor-3000W/dp/B099WNGRVZ

Its a chain drive motor, im worried changing the size will make the issue worse? It launches me right off the bat, I guess its worth a try but I really need an easy way to adjust the power of this thing so my son can grow into it. Limiting torque and speed would be awesome.

Ill try opening up the box aswell and see, but im not really sure what to look for.

But on my controller it says 72v 80amps - in the end I want to be able to have a display of some sort to see battery percentage and perhaps change power settings if thats even possible? Im quite clueless to these things.

Does the above information tell you anything about my problem? Would you also need pictures of the "retrofit build"?

Would something like this fix my problem long term?
https://www.amazon.com/HalloMotor-Intelligent-Programmable-Controller-Colorful/dp/B07BY26XPV/ref=psdcmw_sfl_3405141_t2_B09T797P7N
Not sure what assistance level is but I suppose thats speed?

Edit: i did the soft start thing and that made it slightly better but only just initially of the throttle, if it wasnt so sensitive my son would be able to ride it but it does like 70% accel for just 5% throttle and then the rest. The initial kick is wild. Do you think a sprucket change would Do it better? And just blew a 35a fuse going slightly uphill, shouldn't that hold?

Thanks in advance for any help!
 
Dixonk said:
I forgot about linking what I have, good call. Thank you for the reminder.
Its this kit
https://www.amazon.com/VEVOR-Electric-Brushless-Motor-3000W/dp/B099WNGRVZ
If you look up vevor here on ES, you'll see a few threads about that type of kit, that may have info you can use.




Its a chain drive motor, im worried changing the size will make the issue worse?
If you mean changing the sprocket size? No, if you change the front sprocket to be larger, or the rear to be smaller, it will reduce torque. (it will increase top speed, but that's easier to control in a few ways, most easily by not using full throttle. ;) ).

Ill try opening up the box aswell and see, but im not really sure what to look for.
If you look up "shunt mod" here on ES and on google image searches, you'll see what the shunts can look like. The only really easy ones to deal with are the ones that look like fat bare silver wires in rows right near one edge of the board, usually next to some big cans (capacitors).

- in the end I want to be able to have a display of some sort to see battery percentage and perhaps change power settings if thats even possible? Im quite clueless to these things.
You can use a typical RC wattmeter that's rated for more than the fully charged voltage of your battery and for more than the max possible current draw of your controller, wired between battery and controller, to see battery info.

To change power settings you'd need a controller capable of that, using the display that comes with the controller (they're mostly not inter-compatible so you can't usualy just go buy a display to stick on a controller you already have; getting them as a kit is the simplest way to do this). Or use a controller that can talk to an app on your phone via bluetooth/etc to change settings (though I despise apps for this purpose for many reasons, including that they often don't work right, if you can even understand the badly-translated labelling).

Would something like this fix my problem long term?
https://www.amazon.com/HalloMotor-Intelligent-Programmable-Controller-Colorful/dp/B07BY26XPV/ref=psdcmw_sfl_3405141_t2_B09T797P7N
It might; it depends on it's throttle control style. The best throttle mode you can get for your purposes is Torque control, which changes the current the motor sees, rather than the voltage/speed the motor sees (whcih is how most controllers work, and why you end up with problems like you have now, in high-powered setups).

FOC type controllers generally use the throttle for torque / current control, so they would be easier to control in this situation, assuming the throttle itself that you have has a useful rotation vs output range.



Not sure what assistance level is but I suppose thats speed?
I don't know what you mean by that.

Edit: i did the soft start thing and that made it slightly better but only just initially of the throttle, if it wasnt so sensitive my son would be able to ride it but it does like 70% accel for just 5% throttle and then the rest. The initial kick is wild.
Do you have a voltmeter? If so, measure the signal wire on the throttle, relative to the throttle ground wire, while turning the throttle from all the way off, to all the way on, and note how much voltage you get for how much rotation.

If all the voltage change is within a tiny amount of throttle movement, then you might just want a different throttle. There are numerous cable-operated throttle grips for gas-engine stuff that will also work with electronic cable-operated throttles, like these:
https://www.aliexpress.com/item/32954909008.html
I use that one on the SB Cruiser trike and it works well; pulled by a cheap ATV thumb control from amazon.

That way you can use teh same throttle unit with different cable-pulling devices to get different amounts of throttle for different amounts of grip/etc movement. Eaiser to experiment with than changing the whole thing out (and usually more reliable).


Do you think a sprucket change would Do it better?
What would do it "better" depends on what better means for you. Anything that accomplishes the goal still accomplishes the goal. ;) If better means easy to do, then if it's easy to change sprockets (easier than other fixes), then doing that is better. If it's hard to change them, or really expensive, it is probably not better.

To change them you do want to figure out how much speed it already has. If the speedometer is on the driven wheel, just run it offground and see how fast it goes, and take off about 20% to get the approximate loaded top speed.


And just blew a 35a fuse going slightly uphill, shouldn't that hold?
What is the controller's current limit rating? Whatever that is, is what the fuse would have to be able to handle, continuously. If the fuse is already rated for that, then the controller is not obeying that current limit, and you'd have to progressively test with bigger fuses to find out what it is, or use an ammeter that can handle at least several dozen amps (like many RC wattmeters can), to measure it and then pick a fuse rated above that.

here you say
But on my controller it says 72v 80amps
so you must use a fuse rated higher than 80A or it will blow everytime the controller draws more power than that, which is likely to happen a lot.

Remember, the fuse is really there to protect the system wiring, and perhaps the battery. It should be installed right at the output from the battery, and it needs to be small enough so that the wiring can't be overheated by the current it's rated for. Similarly, you want to limit system current (by fuse or in the controller) to what the battery itself is capable of continuously handling without heating up or serious voltage sag (which causes heating).

If your wiring and battery are not capable of handling 80A, then you'll need to change those to ones that can, before using this controller. Or else change the controller to one that doesn't draw more than the wiring and battery can handle, or modify this one so it won't draw more than they can handle.
 
Wow, this is alot of information to take in, its going to take me a couple of times re-reading your post to digest and understand. English ain't my native language, while im not horrible at it, its far from perfect haha.

FOC type controllers - im terrible sorry for lack of understanding. What is that? And without asking too much, could you perhaps link me a good suitable controller thats programmable, with or without display? For my 3000w 72v motor? Off amazon.com ?
Im worried this controller is abit too much and big for my battery 😅 and I would love to give me son a good experience using this bike.

Thanks alot for your help so far!!
Ordered bigger front sprocket and smaller rear sprocket along with a bigger one aswell. Changing chain and sprocket sounds far easier than soldering off something in the controller. I rather change that thing but theres so many listings everywhere and I dont know what to order.

My best regards
 
In the item description, I see a wire called "3 - speed". If you attach a switch to that connector, you should have 3 speed settings that are pre-programmed into the controller. This would be worth a try. You don't even need a switch to test, just place a jumper wire between the black wire and either of the other wires (one at a time). Typically with no switch attached, it defaults to speed 2. connecting one wire or the other to ground enables speed 1 or 3. In some cases, it only changes the top speed. It may also change the current limit, depending on how they programmed it.

Most controllers like that one have some way to program them, but it may not be easy and you would need their programming software. You might try asking the seller if they can give you the software. With the software, you can program the current limit wherever you want it.

If that is not an option, there are hardware hacks you can do, as Amberwolf was pointing out. If you open up the controller and take a good picture of the board, we can probably find the shunt, which controls the current limit. By modifying the shunt, you can make the current limit whatever you want, but it will be fixed. Lowering the current limit will reduce the maximum torque you get but not change the top speed (unless the current reaches the limit first).
 
Thank you for the additional information, Ive tried the 3 speed switch you wrote about and it does reduce the motors RPM it seems but not the initial torque.
Top speed is the only thing that changes it seems.

At this moment Im more looking to replace my controller with something more suitable and programmable but my lack of knowledge in this regard makes it difficult.
Writing 72v 3000w controller on amazon gives me alot of different controllers but they all look similar to the one was given with the kit.

Im interested in learning more but im quite clueless to where to begin, haha.

Ive ordered new sprockets and chain but I also want to get a new controller. My current 72v 3000w 80A controller scares me abit. Dont want to damage the batteries and such and my son doesnt need this power right now 😁

If above fails, I'll try to make modification to the controller I have but I'll rather replace it than fiddle with it.
Im all ears regarding a replacement

Best regards
 
Is this a Kuberg cross? If so could you post some pictures for the forums. It is overall lacking of Kuberg photos
 
skeetab5780 said:
Is this a Kuberg cross? If so could you post some pictures for the forums. It is overall lacking of Kuberg photos

Hi, unfortunately its not a kuberg as I dont have funds to buy one. The bike im working with is some chinese kids bike, alot of them looks exactly the same but different names.
20220505_133152.jpg
20220504_175259.jpg


Didnt find any better pictures im afraid
 
Why not use a Cycle analyst?

If you are not familiar with the CA it gets wired inline between your throttle and the controller. It has a shunt that measures current and a speed pickup as well as a temp sensor. The throttle signal from the users hand gets manipulated by the cycle analyst before it goes out to the controller allowing you to tame any controller as you see fit.

You can tune the throttle ramp rate of any controller as well as create different profiles to limit current/speed/acceleration etc. It will also function as a dashboard and will give you a temp sensor if you want to install it in your motor.

I think its perfect for your application and will work for any future controller changes you might have. You should also get the standalone shunt with it.

https://ebikes.ca/shop/electric-bicycle-parts/cycle-analysts/ca-sa.html

3kw can do surprise wheelies at low speed on a 26" adult mountainbike. I would imagine that is completely insane for a kid. Nicely done! :D
 
DanGT86 said:
Why not use a Cycle analyst?

If you are not familiar with the CA it gets wired inline between your throttle and the controller. It has a shunt that measures current and a speed pickup as well as a temp sensor. The throttle signal from the users hand gets manipulated by the cycle analyst before it goes out to the controller allowing you to tame any controller as you see fit.

You can tune the throttle ramp rate of any controller as well as create different profiles to limit current/speed/acceleration etc. It will also function as a dashboard and will give you a temp sensor if you want to install it in your motor.

I think its perfect for your application and will work for any future controller changes you might have. You should also get the standalone shunt with it.

https://ebikes.ca/shop/electric-bicycle-parts/cycle-analysts/ca-sa.html

3kw can do surprise wheelies at low speed on a 26" adult mountainbike. I would imagine that is completely insane for a kid. Nicely done! :D

I just ordered a far driver ND72300 controller,bluetooth adapter and a display, hopefully this will do..
Thank you for linking the cycle analysts, I actually tried to order one but apparently they couldn't ship to my address or something. Just got an error and I dont know why..
Feel left out here in Sweden!

I havent been able to drive this bike but I kinda said screw it and geared up my 6yr son and put him on this bike and he just took off, no wheelies or anything, granted the throttle really gave him a kick but he didnt fall off and kept riding.. this thing is blazin fast for him.

I feel quite happy about this bike, the goal was to keep up with pw50s on track but I think this one is faster. Its the damn throttle sensitivity? Or the kick it does initially thats making it somewhat dissapointing..

I wish I could order the Cycle analyst sounds exactly like what I want for my sons bike, do you know if they ship to Sweden? Or where I can buy one that do?

Best regards
 
Photos for those interested
First bike, initially 24v 500w now 1000w 36v, this has good top speed for my son around 35-40km/h (this is estimated from my eyes) but doesnt have enough torque to really shine on kids tracks. Currently 9T front and 77T rear sprocket
20220510_200257.jpg

Battery slides in from the back and plugs to a C14/C15 typical computer / PSU connector - 36v 14ah
20220510_200247.jpg

New bike, initially 24v 500w now 3000w 72v
20220510_200311.jpg

Controller now sits under the seat and is a huge piece
20220510_200357.jpg

Battery location, its not pretty but hey.. first timer
20220510_200650.jpg

Same sprocket setup as above, really want to change but dont really know to what. I have no experience
20220510_200718.jpg

Motor
20220510_200424.jpg
 
That looks really fun. I'm not surprised he was able to ride the 3kw bike. Kid brains are unbelievable. Its the unintended throttle twisting that is really scary. Especially if there are jumps involved. If that controller is anything like the cheap BLDC controllers of the past then a slight twitch of the wrist will send him into orbit.

Every cheap controller I have ever seen is speed based throttle. So when you go half throttle its throwing max current at it to achieve half speed. It makes the throttle response extremely violent and twitchy. The current based throttle logic on the fancier controllers is so much more natural. Nothing wrong with having that much power but after about 2000watts a speed based throttle is annoying even on an adult sized bike.

I am surprised the cycle analyst wouldn't ship to Sweden. As far as I know Grin can sell anywhere in the world. Back before there were a lot of controller options it was the only good way to have a high powered bike. Maybe send an email to Grin's support. I'm sure they can send you one unless there is some weird Canada Sweden tension I haven't heard about.

The nice thing about the CA is that it can tame pretty much any controller so if you can't figure out how to program the fardriver right away you could still use the CA. Its a nice diagnostic tool to have around if you are going to be messing with lots of electric vehicle projects. I run every new build through my CA the first time as a way to double check the current settings I have programed into the controller.

Good luck.
 
DanGT86 said:
That looks really fun. I'm not surprised he was able to ride the 3kw bike. Kid brains are unbelievable. Its the unintended throttle twisting that is really scary. Especially if there are jumps involved. If that controller is anything like the cheap BLDC controllers of the past then a slight twitch of the wrist will send him into orbit.

Every cheap controller I have ever seen is speed based throttle. So when you go half throttle its throwing max current at it to achieve half speed. It makes the throttle response extremely violent and twitchy. The current based throttle logic on the fancier controllers is so much more natural. Nothing wrong with having that much power but after about 2000watts a speed based throttle is annoying even on an adult sized bike.

I am surprised the cycle analyst wouldn't ship to Sweden. As far as I know Grin can sell anywhere in the world. Back before there were a lot of controller options it was the only good way to have a high powered bike. Maybe send an email to Grin's support. I'm sure they can send you one unless there is some weird Canada Sweden tension I haven't heard about.

The nice thing about the CA is that it can tame pretty much any controller so if you can't figure out how to program the fardriver right away you could still use the CA. Its a nice diagnostic tool to have around if you are going to be messing with lots of electric vehicle projects. I run every new build through my CA the first time as a way to double check the current settings I have programed into the controller.

Good luck.

So its common for these relatively cheap controllers to have a sensitive throttle respons?
I have to be really gentle with the throttle to not flip over, feels really dangerous and scary, this makes me wonder who this kit is really for and why it is sold like this to begin with.
Im not really complaining as the price of 200usd was within my budget but now its, 200usd+250usd for the new controller and perhaps an additional 160usd+shipping for the CA v3 because that thing looks really helpful as I want to make something similar for myself so I can ride with my son, that would be extremely fun and I think he would appreciate it aswell!

Speaking of the CA, which one of them should I get? Theres a few to choose from, any ideas? I emailed them so Im hoping they ship to Sweden and I just made an error when I tried..

Speaking of a few other things, how do you know if a battery is suitable for X Ah?
I mean.. theres controllers 15A,20A and my current one at 80A. How do you know if battery can handle it?
The current motor is 3000W 72v and it feels responsive and fast.. do a more "adult sized" dirt bike need more?
As Im thinking of building one myself, this kit for 200usd seems reasonable and easy enough to save up to but I saw another motor rated at 3500 or 5000w for 500usd.. is this a massive difference?
Say I wanted to build something for 600-700usd excluding bike,battery.. that could hit offroads on par or better than my sons 3000w motor.. what should I be looking for?

Sorry for the wall of text and thanks for everything so far!
 
Its extremely common for the cheap controllers to have violent throttle response.

The cheap controllers are basically all the same just scaled up with more mosfets for more power. They were originally designed for low powered ebikes. As mentioned the throttle is asking for a speed. So if you change the throttle angle it applies full current until it gets to the speed your throttle is requesting. With a low powered bike this feel pretty natural because the full current is not capable of wheelies. You can maintain speed without changing the throttle angle. If you reach a hill it applies more current and the rider just leaves the throttle in the same place and continues at that speed.

In the early days of home built ebikes these were all that was available. As the diy community wanted more power the companies building these controllers left everything the same but added more mosfets so the same "brain" could now provide more current. It makes high power very affordable but the control logic was never made for current levels that could flip you off the bike.

So the answer to your question of "who are these made for" is anyone who wants a lot of power for cheap. More advanced control strategies are found on more expensive controllers.

That being said, if you have some device to limit the rate the throttle signal can rise then you can have a lot of fun with cheap controllers.

Thats why the Cycle analyst has a current measuring shunt. By measuring the current it can modulate the signal to the speed based controller to trick it into acting like a current based controller.

If you do get a CA you should get the one without the proprietary waterproof connectors. Get the older style one since you will be adapting it to your non Grin controllers. You probably also want the one with the external speed sensor and an external shunt.

As for what to buy to join your kid on rides, thats really up to your riding level. 1hp is about 750watts. So if you know what bikes you like to ride then you can estimate how much power you will want.
 
There are a wide variety of batteries all with different advantages. The construction of the battery along with the specific chemistry will make it either energy dense or power dense. Batteries are chosen based on their intended application. So laptop batteries are going to have lots of energy but at low power. RC drone batteries are going to have lots of power but less overall energy for their size.

When battery shopping you can usually find the recommended C rating of the cells. 1C is whatever the ah number is. For example a 10ah battery at 1C is 10 amps. Most generic of the shelf ebike packs are built for about 2-5C. You can get RC Lipo packs that are rated for 50C or more in short bursts. So it all depends on what your use case is.

For racing in short bursts with a light vehicle you want high C rated cells. If you have a large vehicle you can use a bunch of low C rated cells and still end up with a lot of power because each battery cell isnt working as hard but it will be heavy. You have to find a compromise between range, power, cost, weight.

This is why cars like tesla have lots of range and power. The cells are relatively low power cells but there are a huge amount of them. If they wanted to use a different cell they could probably make the same power with 20% of the weight but they would have a very short range.
 
DanGT86 said:
Its extremely common for the cheap controllers to have violent throttle response.

The cheap controllers are basically all the same just scaled up with more mosfets for more power. They were originally designed for low powered ebikes. As mentioned the throttle is asking for a speed. So if you change the throttle angle it applies full current until it gets to the speed your throttle is requesting. With a low powered bike this feel pretty natural because the full current is not capable of wheelies. You can maintain speed without changing the throttle angle. If you reach a hill it applies more current and the rider just leaves the throttle in the same place and continues at that speed.

In the early days of home built ebikes these were all that was available. As the diy community wanted more power the companies building these controllers left everything the same but added more mosfets so the same "brain" could now provide more current. It makes high power very affordable but the control logic was never made for current levels that could flip you off the bike.

So the answer to your question of "who are these made for" is anyone who wants a lot of power for cheap. More advanced control strategies are found on more expensive controllers.

That being said, if you have some device to limit the rate the throttle signal can rise then you can have a lot of fun with cheap controllers.

Thats why the Cycle analyst has a current measuring shunt. By measuring the current it can modulate the signal to the speed based controller to trick it into acting like a current based controller.

If you do get a CA you should get the one without the proprietary waterproof connectors. Get the older style one since you will be adapting it to your non Grin controllers. You probably also want the one with the external speed sensor and an external shunt.

As for what to buy to join your kid on rides, thats really up to your riding level. 1hp is about 750watts. So if you know what bikes you like to ride then you can estimate how much power you will want.

Thank you so much for the informative post,

Is it these two that I need?
https://ebikes.ca/shop/electric-bicycle-parts/cycle-analysts/ca3-dps-n-bracket.html
https://ebikes.ca/shop/electric-bicycle-parts/ca-accessories/shunt-ca3.html

or the
https://ebikes.ca/catalog/product/view/id/1199/s/bundle-ca-hc/category/44/
along with the shunt?

or
https://ebikes.ca/shop/electric-bicycle-parts/cycle-analysts/ca-sa.html

I'm sorry these stuff doesn't make much sense to me, haha. I just started doing these things so I'm all new to mostly everything electric related.

Thank you in advance!
 
I think your last link is just a combo with the first 2 links. They all look correct to me. That shunt with the throttle wires coming out of it is very useful as well so you can leave the CA harness intact and just connect your throttle output to the controller via those wires.

Grin switched connectors a few years ago to the waterproof higo style connector. You probably want to avoid that one since your controllers likely don't have the mating pins.

You probably want to stop by the accessories page and pickup a programming cable for the CA as well as an accessory switch. The CA will support multiple speeds or power modes that you can change on the fly with a 3 position switch or a potentiometer. For $12-20 its easier to just get one that is plug and play to the device. The programming cable allows you to configure all the settings with your computer and upload them to the CA. It's easier to look at on a computer screen than scrolling thru all the menus with just the 2 buttons on the dash.

By the time you are all done you are probably going to be into this device for $200-$250. I understand this is a lot of money. There are definitely other more advanced controller options out there that don't require a Cycle analyst. It really just depends on how many different bikes you plan to build in the future. The CA is a bit of a holdover from the old days when controllers were not very programmable.

You could also read up on these controllers
Fardriver
Votol
Nucular
KT
VESC
BAC (ASI)
Kelly

In my opinion the Nucular is the most user friendly advanced controller on the market. Sadly there was about a 1 year waiting list before it became impossible to do business with Russia where they are based. The future for them is a bit unknown at the moment. The guy behind the Nucular controllers is talking about possibly relocating. I hope they do.
 
DanGT86 said:
I think your last link is just a combo with the first 2 links. They all look correct to me. That shunt with the throttle wires coming out of it is very useful as well so you can leave the CA harness intact and just connect your throttle output to the controller via those wires.

Grin switched connectors a few years ago to the waterproof higo style connector. You probably want to avoid that one since your controllers likely don't have the mating pins.

You probably want to stop by the accessories page and pickup a programming cable for the CA as well as an accessory switch. The CA will support multiple speeds or power modes that you can change on the fly with a 3 position switch or a potentiometer. For $12-20 its easier to just get one that is plug and play to the device. The programming cable allows you to configure all the settings with your computer and upload them to the CA. It's easier to look at on a computer screen than scrolling thru all the menus with just the 2 buttons on the dash.

By the time you are all done you are probably going to be into this device for $200-$250. I understand this is a lot of money. There are definitely other more advanced controller options out there that don't require a Cycle analyst. It really just depends on how many different bikes you plan to build in the future. The CA is a bit of a holdover from the old days when controllers were not very programmable.

You could also read up on these controllers
Fardriver
Votol
Nucular
KT
VESC
BAC (ASI)
Kelly

In my opinion the Nucular is the most user friendly advanced controller on the market. Sadly there was about a 1 year waiting list before it became impossible to do business with Russia where they are based. The future for them is a bit unknown at the moment. The guy behind the Nucular controllers is talking about possibly relocating. I hope they do.

Alot of information! I ordered a fardriver which is on its way from China - will probably take a month if not more before it arrives.. (if it does) haha.
Took abit from my savings and ordered a CA aswell, just have to figure out how to program that thing so the bike is better for my son, any tips in that regard?

Thanks alot for the help, if I end up using the CA or fardriver on my sons bike - i guess whichever is easiest and I'll grab the other one for my own future bike..
Theres way too many motors and controllers out there, this is giving me a real headache haha.. how do you even know if a kit is good or not?

Best regards
 
Dixonk said:
Took abit from my savings and ordered a CA aswell, just have to figure out how to program that thing so the bike is better for my son, any tips in that regard?

The CA is best used with the dumb controllers that have no programmable settings/etc. Then the CA does all the smart stuff, and doesn't conflict with anything hte controller is trying to be smart about. ;)

When using the CA for limiting, it depends on what you want to restrict as to how you'll set it up. If you want to restrict just sudden power bursts, you can use the throttle ramping features to prevent any sudden increases in throttle (but still let it ramp down very fast to let power off as quickly as needed).

You can use current-throttle or power-throttle modes to let the CA smooth out the throttle response, so that the throttle is no longer controlling hte speed, but rather is ocntrolling the current or power of the motor (more like a gas engine's throttle).

You can also limit speed of the whole thing, so that it can't exceed a certain speed, regardless of how much power is available or the conditions you're riding under.

There's other parts of it you may also use, but some stuff like any of the PAS / torque sensor modes don't apply to your bike, as i doesn't have the pedals to do this. (there are ways you could use those inputs for other controls to do similar things, but I can't see any need for them here).


I recommend going thru the entire manual first; print it out if you don't have a hardcopy and make notes on the pages with stuff you need for settings you think you want, so you can specifically set those as needed during setup. Then mark stuff you know you don't want, so that can be disabled / etc during setup. Whether you use a function or not, you'll still need to verify that section is setup as needed for your specific requirements during setup.

You can do this manually in the menus on the CA itself, or you can use the USB-serial cable to do it on a computer via the setup program; the latter is easier because it's all on one page (more or less; you still have to scroll up and down) (and you can save various setups as separate files to swap out for experimenting), but you can access all the important settings directly within the CA's onboard menus.





As for how you may know a kit is good or not? Well...it's tough. :/

The best you can do is determine what specifically you need a bike / etc to do for you, and under what specific conditions it needs to do that. That lets you figure out the power you must have in a kit. Then you make a list of the specific ways you want the system to work for you, like what you need a display (if any) to show you, and any settings you want to be variable and user-programmable. Then which of those things you need to be field-settable (in the display/etc), and which you can live with using only a computer / etc to program them.

ONce you have all that, then you can severely narrow down the field of controllers / motors / batteries / etc., as very few will do all the things you want. Sometimes none of them will, as kits, and you'll have to pick and choose various parts that will do what you want. Sometimes you simply can't find the things that do everything you want, and then you either compromise on those things, or you don't build it, or you do what a few have done and design and build their own stuff that does do it. :lol: (like me; I couldn't find reliable controllers that had the features I wanted for my cargo trike, so I started a project to hack a Lebowski controller brainboard into an EV car controller powerstage...I still haven't completely finished that).

But you can usually find all the important requirements in at least separately-available parts, if not in a kit. Can take a while, so the best way is to make your lists of requirements/etc, then post them, then people may be able to suggest stuff that does them.


Note that the more programmable a system is, the more adaptable it is to your needs, the harder it is to setup in the first place, because you can't just setup the bits you need, you have to setup the whole thing to work as you need it to, or it often doesn't work at all. :(
 
One thing you might consider is looking for a motor sprocket with more teeth. The one that's on there is extremely small and that can't be good for noise and wear. By going to a larger front sprocket, the motor will be geared higher, so more likely to hit the current limit and less likely to wheelie. Top speed will be higher, but the 3 speed switch or a throttle limiter can bring it back down to whatever you want.
 
Thanks alot for everyones input,

I'll download and print out the manual for the CA and go step by step, but maybe someway to just lower the initial torque or "kick"? would suffice, would make it alot more fun to ride for my son, its really the only downside to it at the moment. it isn't as quick as I expected it to be once I dared to slowly throttle the bike up, son handles it way better than me but I didn't want him to max it out - could be due to the lower front sprocket but it reaches a 50km/h, it needs to have good enough torque so he can complete the track but certainly doesn't need that top speed at the moment. It's way faster than the pw50 from what I've seen.

I've order both a bigger front sprocket and bigger rear sprocket but it seems to be taking forever to reach here, could be due to the chain size as its only a 25H at the moment, should maybe change to T8F as that seems to be way more common on bikes.. you learn as you go..
It's funny thought, the bike "stock" at 24v 500w retails for around the same price I got the bike second hand with the new motor kit at 3000w.. I'm glad I didn't buy this new, certainly not worth the money!

Regarding motor for myself - I was thinking first of going cheap and using the same motor kit my son has in his bike but 4hp doesn't sound nearly enough for a midsize bike - have to follow my budget carefully as I certainly don't have much money to spend..
do someone have any kind of information about this motor?
https://www.alibaba.com/product-detail/YMMotor-3500w-5000rpm-72v-DC-Mid_1600486543502.html
or if a qs138 would be much better?

I would have to use my ebike batteries I bought for cheaps to build batteries, I have enough cells to make a 72v 30ah battery to start. I dont think I can spend more than 700-800 absolutely max on motor and controller in total.. and safe up money for a better battery overtime.

Best regards
 
Dixonk said:
I'll download and print out the manual for the CA and go step by step, but maybe someway to just lower the initial torque or "kick"? would suffice, would make it alot more fun to ride for my son, its really the only downside to it at the moment.
That's what the throttle ramping can do, and/or using power or current throttle control instead of "speed".

First I'd try the power or current throttle modes, with ramping set at 99v/s (fastest it will do). If it's still not tame enough, set the ramping to whatever takes enough time to reach power it gets set to that it works the way you want. Start at like half a volt/second, and work up or down from there.

Set the throttle down ramp to 99v/s for "instant off" so if you let go of throttle it stops applying power, regardless.
 
Since you are OK with the total amount of power but just want to tame the throttle ramp I would suggest removing all the power limits thru the CA3 and setting the throttle in Pass-thru mode. This will eliminate some of the more tricky gain settings that come into play when you are actually trying to limit power. I think you will be fine just using the throttle ramp/time settings to do the taming.

I would start like this:

Begin with the throttle input and output voltage minimums. Start with the wheel in the air and the CA throttle set to bypass. Your controller is looking for about 1v closed throttle and around 4v full throttle. There is a throttle input/output display screen on the CA3 that will show you the throttle signal in vs what its sending out. You can use this screen to figure out at what voltage the controller starts to turn the motor. You will set your minimum throttle out just below this point. You also can use this screen to figure out the minimum signal your throttle is sending out when its closed. You can set the minimum throttle in just slightly above this point and it will eliminate the dead spot at the bottom. Even without the throttle output of the CA3 going to your controller you can use this throttle screen to make sure everything is set as responsive as possible. Its pretty clever. Basically you are looking for the CA to not be sending any signal out when the throttle is closed but you dont want the first 10% of throttle twist being ignored either. Once you get that set set the CA in pass through and move on to the throttle output ramp rate settings.

Try a throttle ramp up of 0.3 - 0.5 volts per second to start and increase from there. When you get up around 5-6v per second it becomes almost imperceptible to human brains and will probably feel exactly like the controller did without the CA. Do this testing with smooth continuous accelerations. Once you get the acceleration how you want then move on to the fast throttle up settings.

Start with the Fast throttle up rate to 1-2V/sec. The fast throttle up eliminates the dead band or slack in the throttle when the bike is rolling along at speed. It ramps the throttle up super fast until it feels a slight load then it reverts to your normal throttle ramp. It makes the bike feel way more responsive from a roll. Otherwise a bike rolling along at moderate speed will feel like there is a delay and then a hard kick. A motor free spinning with no load will consume about 1-2 amps. If you set the Fast throttle up current threshold at 2 amps then when you are rolling along at speed and you tip into the throttle it will will quickly ramp until it feels 2 amps and then it knows it has caught up. Once this is all set correctly the bike will feel very responsive but not any more violent than it does when accelerating constantly from a dead stop. If you set the fast up current threshold too high then it will kick for just a second and then smooth out to normal acceleration. The goal with this is to eliminate all of the slack/delay when throttling from a roll but not have it overshoot because its ramping up super fast. Its a bit of a balancing act.

If you got the programing cable and the CA3 parameter editor you can post screenshots of your settings and we can probably help a bit if you are having trouble. The instruction manual is really good too. I'll look around for one of my CA files from a 4kw chain drive motor I had. That might give you an idea of some starting points.
 
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