Electric Bike Help

This is probably a long shot but---My wife has MS so we bought her a trike. This became too difficult for her to pedal so we bought an electric front hub motor (3 wire PWM, 250W, 24V). Unfortunately there is no speed adjustment; just on (fast!) or off.
So, I investigated the no-name, no schematic "Controller for Brushless Motor". Green, blue and yellow wires to the motor. Orange and pink wires that disappear into the 7 pin connector (possibly connected together?). Finally a red and black wire pair that connects to the handle bar on/off pushbutton and probably switches the battery 24V. The controller's label has a note that there is a "throttle adjustment voltage 1.2 -> 4.4V.
So, we want this thing to have a slower top speed (kinda funny to say that on Apexspeed!). What are the chances that a variable resistor spliced into the handle bar switch could lower the amperage to the controller and thus reduce the speed?
Marty

Hmmm.. I'm interested as I'm building my wife a track cart out of some old mountain bikes and a scrapped wheel chair.
If that is a 24v motor, have you tried running at lower voltage - like say 12v? I find some of the scooter/bike conversion blogs are always upping the voltage for more power - so less = less?

Just off hand that VR might get hot. Make a nice DC toaster?

Cheers - Jim

In a DC motor, rpm is proportional to voltage. Just make certain that any potentiometer you utilize can handle the load.

does the place you purchased the hub motor from offer a speed controller that will work with it?

I would recommend against the spark-o-matic variable resistor idea that would need to dump the power as heat or worst case, short out with full power on. I recommend off the shelf parts that are made to work with the motor you have. I have built a Pulse Width Modulation speed control for some lab tools, but DIY will be more expensive than buying the china controller for the china motor you have. Looking through the e-bike forums will probably get you better results than on here. SCCA has not been too favorable towards electric power.

Understand the need for slower top speed as there are speed limits in paddock. I picked up a Rad Mini folding fat tire bike for Dana to be able to walk courses and get around at events. The racks for hauling drinks, tools, anything short of tires is handy. After her back finally went kaput, it's now my pit bike. I've had to repair the components inside the speed controller. Bouncing down the interstate metal fatigued some capacitor leads. Some RTV silicone helped as a vibration damper during the repair to prevent the break down in the future.

Thanks everyone.

"have you tried running at lower voltage - like say 12v"
Might be a good idea and then I would have a spare battery too!

"does the place you purchased the hub motor from offer a speed controller that will work with it?"
They appear to not have any idea what they are selling. Probably buy kits from China and slap their own sticker on. They weren't even interested in finding a schematic for me. They did suggest I buy the higher priced, higher powered kit which has a twist grip controller and many more wires into the motor.

Amusingly enough, I thought I would be able to find a similar model controller by looking at Google Images. No luck. They all seem to use a similar aluminum box but with a vastly different array of wires exiting.

Marty

do you have a part number and manufacture on for the motor you have?

Quote:

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Originally Posted by TedV

do you have a part number and manufacture on for the motor you have?

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Yes, it's a Bafang 8Fun 250W/250 Series.

I would suggest posting your questions to a drone forum or looking to that community via searches, etc for help with the controller. Drones are probably the largest non-industrial users of brushless DC tech.

actually better forums are https://endless-sphere.com/forums/ then scroll down to the electric bicycles section. Another one is https://electricbike.com/forum/ The drone forums will find the wife in a flying bike. hhmmm.. :thumbsup:

The color of wires from the motor makes a difference as I think there are a few options. For instance, red/black/green might be the easiest to use a simple PWM controller on Red=+V, black=ground, green or another color usually for the hall effect speed sensor. If wires are something like blue/green/yellow it has a phase array like a stepper motor and needs a controller to match.

Since you said you have wide open or nothing, I'm thinking you have the red/black/green. I'm not liking the vendor you're dealing with don't know what they are selling. Kits are usually the way to go as everything is supposed to work together. The kit they want you to buy sounds like the phase array motor. Kits may have switches on brake handles in the kit so the power gets cut to the motor when the brakes are applied. You don't need any Audi un-intended acceleration at the worst possible moment.

There are some PWM speed controllers on amazon and ebay with rotational pots to set the output speed along with an on/off switch. Not as good as a thumb control or twist grip as just let go of the hand control and it should go back to zero output. You don't need cruise control on an ebike.

A lot of this is speculation as I do not have all the components you are dealing with in front of me. My day job involves tracking down data sheets, schematics, and electronics assembly from soldering under a microscope to wiring harnesses using welding cable.

Double and triple check all schematic, wire connections and operations of the bike. You can only let the smoke out of electronics once. Also a crash can be worse than letting the smoke out.

Thanks Ted,
Actually, I mentioned in the original post that I do have "

wires are something like blue/green/yellow it has a phase array like a stepper motor and needs a controller to match". I wish I had your talent for searching for schematics and things. As it is, I have no idea what is in the controller box. I'll try the forums that you noted.
Since I used to be involved in English cars, I am familiar with the Lucas concept of "smoke". That and laying under the car and having oil drip on my face.
Marty

Marty,
DOH! my bad. I misunderstood. It's easy to get confused via the internet. lol I thought the wiring you found was schematic for generic speed controller on the web and didn't match up to the motor wires. What all parts do you have? I thought you didn't have the controller but somehow got the motor to turn over wired directly to battery. If you post a picture of the sticker on the controller box you have, I might be able to find more info. Also, info on where you got it.

I looked at my bike. The Bafang motor only has 3 wires to motor but can't see the internal wire for colors without breaking open the sealed harness insulation. Part number on my spare speed controller is LSW765-48M which has a cutout voltage at 40V. Meaning it wont work for your 24V system. Substitute 24 in the product number and all the controllers I find require Hall sensor wiring to the motor. The other multi pin connectors connect to intermediate harness that go to the dash, throttle, pedal assist sensor, brake levers, etc.

If your motor only has the 3 wires, has the speed controller, has the master on/off switch and all you are missing is the throttle control, a variable resistor might be all you need. Look at the sensorless brushless BLDC motor controller at https://makermotor.com/pn00110-24c-b...ontroller-17a/ Down the page it has some explanations on the wiring that might help. Note the section, connect to potentiometer for manual control. I'm now hoping all you are missing is the pot to dial the speed you want. More rider friendly than a dangling or zip tied pot might be throttles like found at https://www.electricscooterparts.com/throttles.html

Morning Ted,
Now you are expecting me to know how to post pictures!?

The label says:
Controller for Brushless Motor
Rated 24V
Max 15A
Rated 7 A
Throttle Adjustment Voltage 1.2 - 4.4V
Product Number LSW1124-1 x17110003887
CE: G3M20211-1592-16

The controller wiring is:
Red 24V and Black ground which is routed from the battery through the handlebar momentary contact switch
Green, Blue and Yellow to the motor
Orange and Pink that go to the 7 pin connector but don't come out the other side (My first thought was that might be a good location to insert a pot or even a fixed resistance but not knowing how to guess at resistance, I didn't want to LET THE SMOKE OUT!)

The battery is a Samsung 10.4 AH 30K

Don't forget, Sunday is Flag Day!

Marty

yeah, I'm not even sure how to post pictures on here. :confused:

Do you have a link to the web page you got it from that has any kind of pictures or info? Or was it a local dealer with no internet sales?

I'm finding all kinds of different specs on controllers with similar partial numbers. The product number and CE# together still returns controllers with more than 7 wire connections.

The boards can be wired up several ways. Are there only 7 wires going in-out of the controller? All the voltage and current goes through the momentary switch so it gives the equivalent of turbo boost WFO throttle any time the button is pushed? I still feel I am missing something.

Is this motor a simple DC motor, or an actual PWM motor? If a simple DC motor, you can only control the speed by varying the input voltage. If a PWM motor, yes, you can try simply varying the voltage, but with the generation of lots of heat and low efficiency. For a PWM motor, you really want a proper PWM controller that varies the pulse width. Plenty of them available on line very inexpensively.

Quote:

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Originally Posted by R. Pare

Is this motor a simple DC motor, or an actual PWM motor?

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Bafang 8Fun should be a Brushless DC (BLDC) motor so it is not a simple DC motor. It needs a Sensorless controller if only 3 wires come out of the motor. Sensor controller if it has 3 big wires and 5 little wires coming out of the motor. Endless Sphere has info on how to sort out the phase connections to the motor from the controller if the same color wires don't work out when connected. There isn't an industry standard color code on china e-bike parts. more like suggestions.

"Do you have a link to the web page you got it from that has any kind of pictures or info? Or was it a local dealer with no internet sales?"

I bought it from an outfit called LEED electric bike (e-bikerig.com). I recall the site having pictures of both the motor and the controller but no actual details. I have been trying to find a St. Louis based local electric shop but haven't had any success.

As a funny aside, a few years ago I built a street car based on my old DSR except two seats and with a Honda CBR1000RR motor. The local license agency would not recognize the motor so I thought it would be good to try electric. At the time, I never could reconcile the 1000 Lb of lead-acid batteries so I sold it. Looks like I probably would have run out of electrical talent on that one too.

Marty

looked over the LEEDS site. I stumbled across what they call a 24V push button controller that sounds like what you have. If I understand it all (and I still feel I am missing bits) your choices are:

1) Assemble what you have and the wife taps the power button on the handle bar as needed to run the speed she wants. This will be herky jerky and in my opinion a pain.

2) I don't think this one is for you. Open up the speed controller. Research the board you find. Make connection and wiring changes to let you set it up to run a potentiometer as a throttle. Maybe someone on an ebike forum has done it. I don't have the time to search that out. A pulse width modulation connection that replaces the on/off button could work here. If I have to explain the circuit and how to track down how to build it, this is not the option for you. Not to be brutal, but this is the hard way. My coworker fried $5K+ worth of electronics in the last 2 days in name of research as a couple of 300+ connections of a new board to a daughter board or something yet to be discovered screwed the pooch. Smoke can be expensive.

3) find another speed controller like the one I linked earlier that indicates the wiring for a throttle that will let you run the motor you have and the battery you have, add a twist or thumb throttle, system on/off switch, Battery monitor is included on some of the throttles I linked on the electricscoooter page. Like R Pare mentioned, this is the way. ( anyone here watch the Mandalorian? or do I hear an echo??)

4) any of the local colleges have a FSAE team? Find an electrical adept student willing to whip something up. I know members of the local team here are pulling their hair out, bored, pissed that it has gone to a virtual competition. Several are looking for a challenge as they are bored. If you were closer I would be working on your controller. I fully understand how it is when someone who wants to get around the event site, can't. It sucks.

Back in 2015, I opted for a complete working folding bike easy button that would work for my lady at $1500. I could have done a non-folding bike at $800. I could have done a DIY build with parts for $400-$500 but I had no time. Unless the folks at LEEDS can help you sort out what you have to work for your needs you may have to ramp up the cash outlay. From personal experience with someone who doesn't feel or control much below the belly button. Watching them get around and enjoy is bliss.

As side note, I have tried to get electric propulsion included in SCCA competition. A good fit for autocross. Low sound levels, short runs that will not over tax the batteries, the controller, or motor. a very good fit if a little engineering (math) is applied. I have supplied alternative energy rules developed by the FIA that include extreme battery safety. I have supplies sections of rules that have the FIA/CIK sanction where the FIA/CIK covers rules accepted by SCCA for karts. I've included data, lap times of equivalent EV karts to gas motors that follow the FIA/CIK rules of 125cc shifter karts. The SCCA SEB then moved the goal posts stating that "electric has too great of a potential" and therefore not allowed. Not realizing that simple watt meter and math can be used to police the power. But I'm not bitter. :ha::beer: LOL