Transforming a $156 scooter into a 20mph wheelchair

[nonoise]

...
I DO know that horsepower is in some ways irrelevant; speed of a motor vehicle is always a direct function of available torque at that speed. Watts when dealing with AC motors is V x A= W (roughly-AC is not DC!), so it implies that "you can't have one without the other" (love & marriage) They do go together like an electric carriage I guess.


Brushless motors are 3 phase and have 3 power wires/no ground, and use alternating current. The Halls generators, which are a kind of electronic position sensing switching device, inform the controller of rotor position and hence when to turn on or off the next phase legs to rotate the motor, which leaves you with 36! possible combinations of sensor and phase pairings, only 2 of which work!
Apparently some brushless/3 phase motors will work without sensors but none I've seen so far....clip...

Brushed DC motors are easy to control and reverse-just reverse the poplarity. I think you can reverse a brushless 3 phase motor by finding the right timing for the phases and the sensors, but that would require 8 wires to a 4 pole double position switch with 4 wires being heavy enough to handle high current, something not at all practical! I'm counting on these new controllers to do that with two wires.

So I should tell you about a couple of things I learned along the way with my recumbent trike and smart drive hack. First the trike, It was a 36 volt brushless 500 watt rear hub motor with *reverse*. After construction by the ebike shop, it would not go uphill good enough. So I requested an upgrade to 48 volts. But they told me I would have to upgrade the controller also. They also said that alone would not solve hill climbing. They claimed I really needed a more powerful wattage motor. They were not wrong, but the extra voltage enabled me to get a run at these hills and make it over the top.The take away here is voltage and watts of the motor may need to match the controller. However this costly lesson was years ago, and I know newer controllers are more forgiving.

As for going in reverse, geared motors never used to do reverse. Those are the smaller ones. The bigger pan motors can do reverse.

As for those hall wires, you don't need them. The controller/motor will figure out what to do on the first startup. Smart Drive doesn't use them and I didn't either on my clone. There is an issue still in getting the wire colors correct. Yellow might connect to green. There seems to be no standard. If you know the name of the motor and controller you might find the code on the internet. I might still be able to find mine, but they are old.

[Gordy1]

So I should tell you about a couple of things I learned along the way with my recumbent trike and smart drive hack. First the trike, It was a 36 volt brushless 500 watt rear hub motor with *reverse*. After construction by the ebike shop, it would not go uphill good enough. So I requested an upgrade to 48 volts. But they told me I would have to upgrade the controller also. They also said that alone would not solve hill climbing. They claimed I really needed a more powerful wattage motor. They were not wrong, but the extra voltage enabled me to get a run at these hills and make it over the top.The take away here is voltage and watts of the motor may need to match the controller. However this costly lesson was years ago, and I know newer controllers are more forgiving.

Your bike shop was definitely correct about needing to upgrade the controller to match the upgrade in battery voltage. Whilst some controllers specifically state that they can handle two or three different voltages, most are designed for only one.

I just caught up with a mate who is far more intelligent than me...I asked him about how torque relates to power (Watts) in a hub motor, as I didn’t notice any difference when upgrading voltage on a motor. He gave some interesting responses (which I hope I’ve remembered correctly!):
1. The larger the diameter of a hub motor the larger the “lever arm” (between the centre and the magnets around the perimeter), so the larger the torque.
2. The wider the hub motor is, the longer each magnet is, which again increases the torque.
3. The more amps (and/or volts) you can supply to the motor, the greater the torque.

So by just measuring a couple of things on two different hub motors (which have the same power (Watts)) you can tell which has the greater torque. (Apparently the number of windings within the hub motor also has an effect on torque, but you can’t tell the difference between two motors without opening the motors up.)

Obviously larger powered/wattage motors get larger in size, so also provide larger torque, but I thought he provided some useful info if you need to compare motors before buying.

He also said that electric motors have such high torque anyway, than I may not have noticed a slight increase in torque when increasing battery voltage. He’s probably right (as he usually is, but not in a smart-arse way, thankfully!).

[pfcs49]

Gordy1: "Your bike shop was definitely correct about needing to upgrade the controller to match the upgrade in battery voltage. Whilst some controllers specifically state that they can handle two or three different voltages, most are designed for only one."

Yes, I wonder about that. Some people (Endless Sphere) talk about simply putting 48V to a 36V controller but you must replace any electrolytic caps that aren't high enough voltage (and two caps in the KDX controller meet that criteria) but (most? all?) controllers have upper and lower voltage cutoffs to protect the battery. How to do that?
The replacement ones have a "learning" line you connect upon powering up the first time. Allegedly it does the logistics of timing the sensors to the phases; don't know, haven't tried one yet. Perhaps it resets cutoff parameters to the new supply voltage?

I'm off the electrics/frankenscooter for now. I've never really been satisfied with the implementation of the lower latch deal. The first was foolproof/rigid, but difficult to adjust the final tension; the second was quick but susceptible to the tensioning lever on the eccentric clamp possibly coming loose during use.
I need this to fit my trusty Ti Sport as well as the new aluminum piece of shit Medicare demanded I take. Both have different footplate architecture and thicknesses which requires the latch to work in two different positions 1/4" apart, complicating any over-center snap shut implementation.
Yesterday I finally got the Ti out of the GTI where it resides, and tried it. Worked. Sucked. Decided to make a 3rd implementation.
The third time is a charm!

(I figure I need to get complete with the basic design so this works as well as possible, then I can do whatever with electrics and motors, and build another "chassis" that works.)

PS: when I get the latch nailed down, I WILL make a video. I'm not bragging. This is the easiest, fastest to mount trike deal of all those I've seen.
Anyone in a manual chair needs this! I can't tell you how freeing it is to wail down the lane at nearly 20mph in your good ole chair! It's alternate reality!
It's like the fantasies I had when I was 7 about beating my arms hard enough and levitating!

[pfcs49]

Done! And it is a winner!
It is the easiest of the three to use and it absolutely locks in the foot plate. Just need to take it back apart paint it and slap it together.
It looks like my Thanksgiving day agenda is to get back on the electric part so I can make the hilly dirty cheer scooter

Here it is, first clamping the TiLight foot plate template, and then in the disengaged State.
If the vertical shaft & knob is pre-adjusted to the chair (which would be normal unless changing chairs), then after I've landed the foot-loop into the pair of receivers, I put down the aluminum lever on right which swings the 1/2" horizontal clamping bar down; it will have slight resistance as it brushes the footplate on it's way a little forward where it stops against the green part; it' semi-locked but since it went over-center, it is now above the footplate. That's what the knob and vertical shaft are for. Three CCW turns of the knob and the clamping bar is tightly pressing the footplate loop into the two "U" shaped receivers and the chair is locked to the machine.
Plug the two pip pins on the upper "radius" rods, turn it on, and GO!

[vjls]

Theoretically, Watts is the same as horsepower and horsepower is a function of torque and RPM. Perhaps an electric motor produces a constant torque at all RPMs? (IC motors, torque falls off as RPM increases BUT horsepower is a function of RPM so it peaks after torque has fallen a good bit)
I know there's some factor with these brushless motors that there's an inherent speed limit on them, perhaps dependent on AC frequency? I should do some reading but having too much fun still!
I DO know that horsepower is in some ways irrelevant; speed of a motor vehicle is always a direct function of available torque at that speed. Watts when dealing with AC motors is V x A= W (roughly-AC is not DC!), so it implies that "you can't have one without the other" (love & marriage) They do go together like an electric carriage I guess.


Brushless motors are 3 phase and have 3 power wires/no ground, and use alternating current. The Halls generators, which are a kind of electronic position sensing switching device, inform the controller of rotor position and hence when to turn on or off the next phase legs to rotate the motor, which leaves you with 36! possible combinations of sensor and phase pairings, only 2 of which work!
Apparently some brushless/3 phase motors will work without sensors but none I've seen so far.

Brushed DC motors are easy to control and reverse-just reverse the poplarity. I think you can reverse a brushless 3 phase motor by finding the right timing for the phases and the sensors, but that would require 8 wires to a 4 pole double position switch with 4 wires being heavy enough to handle high current, something not at all practical! I'm counting on these new controllers to do that with two wires.

The Chinese aren't terribly helpful with their info. We are supposed to be electrical engineers! I dread to have to go through the drudgery of trying 36 combinations of wires! The Halls and phase wires are mostly color coded the same; but my reading informs me that there's no agreement about the timing of them and many will need to just do trial and error
Of course, the KDX wiring uses much more compact MPCs (Multi Plug Connectors) than the aftermarket ones. That's why I got myself both kinds of kit so I can make adapter harnesses OR change one set of connectors to unify, but first I need to get one swapped, then (hopefully) the other controllers will be identical in their color coding. I may be dreaming.

PS: I've enjoyed your projects and videos. Great stuff and I hope I can get to your level! (there's STILL a 15 year old in me that wants to fly!)

that is so neat i was wondering how thaat was coming get that out there lets see some video have fun

[maddog]

Done! And it is a winner!

Nicely done, you should be proud, I know how much thought and time goes into things like this. One step forward, two steps back until you finally have what you want. I am working on my car wheelchair lift trying to add a backrest to give me more stability while I drive. Right now I am going through the 300,000 car seats for sale on ebay to find the best fit. All these homemade projects take a lot of effort to get right but it is rewarding when you do.

[comad]

One design that looks too simple to work properly I think
See this YouTube Video

[juniorsenior]

I know that the gen 1 Firefly had two speed limits which could be changed via the controller if you knew how (ie it involved some special sequence of buttons, it wasn’t an obvious selection on a menu). What speed are you currently limited to?

Gen 1 was 250W, and the wheel diameter was pretty small. Having now played around with larger wattage hub motors (which includes a 500W 36V set-up that can go at about 35km/h), I’m not convinced that the Firefly one could have gone much faster than the higher factory setting. Although I admit that I don’t actually know what ends up being the limiting factor in hub motor speed. Chinese controllers don’t seem to specify a speed limit, but that may be because they don’t know what diameter of wheel the controller will be used on, and that obviously affects the speed (but not the hub rotation speed).

I took a look inside the hub and it is indeed a geared motor. There are like 10 wires connecting it. That pretty well eliminates an upgrade possibility, correct?

[nonoise]

I took a look inside the hub and it is indeed a geared motor. There are like 10 wires connecting it. That pretty well eliminates an upgrade possibility, correct?

It depends on how hot the motor windings get. I've seen some videos of hubs smoke and catch fire on bench tests pushing their limits.

[pfcs49]

I took a look inside the hub and it is indeed a geared motor. There are like 10 wires connecting it. That pretty well eliminates an upgrade possibility, correct?

A brushless motor with Halls position sensors will have at least 8 wires (3 phase, 2 power/ground for sensors, 3 sensors signal; if it has a temperature sensor sensor it will have at least one more for the sensor, possibly a pair.

Sounds like a fairly normal/swap-able deal.

[juniorsenior]

https://www.aliexpress.com/item/3284...5585243bbpPBep

Would I (theoretically) be able to put this motor in? Would it be easier replacing the existing Firefly controller and putting everything to their controller?

Here's what I am worried about - 1st gear is GREAT for apartment/indoor use. I worry if I don't have that gear that I would constantly be spinning my tire and leaving rubber marks on the floor. Do their controllers have electronically limited "gears"?

[pfcs49]

Good questions and I don't know the answers yet!
You certainly could run that motor off your controller and I expect you'd still have all the functions intact.
I haven't yet crossed that Rubicon but will soon.
To get the aftermarket motor working, all you need to do is get the timing of the 3 phases and the 3 sensors right, The wiring has a protocol. Here's one of many articles about swaps.
https://www.google.com/url?client=in...-t7gkBxpJM13No

If you have the Yellow, Green, Blue heavier phase wires, and 3 lighter Y, G, B wires (Hall sensor signals) and Red & Black (B+, B-/ground) small wires, hook them up to match, limit the current, and hope it's good to go!
If not, there's info in my link about swapping things around until you find the right combination; I think there's 36 possibilities! But that should be your only difficulty. If you do have one or two extra wires, they're probably to a temperature sensor. If you DO have extra wires, I'd investigate before buying a motor. If you disconnect it/them, does the device still function? While they're apart, you might put an ohmmeter across them, or if only one extra, from it to the black/ground Halls sensor wire. I hunch it's a NTC resistor/sensor. If you get a good ohm reading (somewhere between 600 and 2K ohms), heat the motor with a hair dryer and the resistance should go down considerably with temperature. Now, you've pretty much confirmed what it is and I wouldn't hesitate to run the aftermarket motor without it.
If it won't run without that circuit, you could substitute a resistor across the pair to fool the controller OR possibly install your own overheat sensor on the new motor. Many are available from Digikey or other electronics suppliers.

Pay attention to what he says about current limiting until you get it right! I made up a 12" jumper with battery plugs at each end and a fuse holder in one leg w/5A fuse.

Most aftermarket controllers have a pair of "learning" lines. Allegedly once you have the phase and sensor wiring hooked up the controller will see which way to time things and you're done.
I haven't yet tried this because my first gambit is to try swapping a controller, but there's a 6 pin and a 3 pin multiplug from the handlebar controls & display to the motor controller. I'm obsessing trying to parse the logic of those circuits hoping I can find a way to swap controllers while maintaining the original functions like cruise, 3 speeds, mph, odo, voltage, etc which IMO are real nice to have.

[pfcs49]

I wired up extension harness from the battery box up to the parcel bag so I can run a pair of the batteries if I want to. I am hoping that doubling the current available will make it go up hills better but I expect that the motor controller limits the current so you can’t burn the motor up! At least it’ll go twice as far

[pfcs49]

Tonight I made up some conversion jumpers (KDX flat/small gang connectors>>>white, large, box type) so the aftermarket throttle (KDX style plug) and KDX motor Halls plugs would connect with an aftermarket motor controller that has a reverse function. After all the concerns about solving a 36 step electrical puzzle, the controller worked out of the box!
The reverse function works-just need to rig a handlebar switch.
The controller is a little bigger in all 3 dimensions so it will require a hack (quite literally) to get it into the battery box, but not much of a problem.
First step is to get out to the big hill and see if dual batteries gives more torque, then I'll be delighted to hack away!

After I figure out if I can rewire the handlebar wiring to the new controller so the original throttle and processor/display work with aftermarket motor controller, and all that's nailed down, then I'll cross my fingers and substitute the 48V 10Ah battery and see if it still works with the original display/throttle.
It sure would be nice.

[nonoise]

It looks like you had no trouble matching colors. I wonder if these things are becoming more standardized. I did do some Reading up on where my first parts came from and they have leaped forward so far now most of it doesn't even look like what you have. ebikes.ca Yours is like my stuff. Except you have better controllers since they do more. One note is that that I quit using that thumb throttle in favor of a motor cycle style twist throttle. But I think you already are there. The thumb type is dangerous, too easy to get accidentally flipped. Been there, done that.

[pfcs49]

Today I did the big hill with one and two batteries.
The thing goes a little faster up a very steep hill, 4mph two batteries vs 3mph one battery, but I'm looking for enough torque to rip up such an incline. I need to finish up with the reversing controller, seeing if I can get the multi-function dipslay/controller to work with the aftermarket motor controller. Once I've exhausted that pursuit, I'll try a 500w/36V controller and see if it climbs hill fast without burning out the motor, then I will move on to testing 48V scenarios.

[nonoise]

I'm really curious if your system will reverse as it should be a geared motor. Way back when I had to go with a direct drive motor because I wanted to have reverse for my recumbent trike. But those larger diameter motors meant shorter spokes. And short spokes would not stay tight in a small diameter wheel.