Ultralight DIY mobility scooter hub motor and controller - AKM-Q75SX?

[joeka101]

Hi,

I've read as many related threads as I can find - apologies if this is duplication.

I am building a lightweight mobility scooter for my father (Wt approx 100kg). Ive tried modding a AovoPro scooter in to a trike but it's still too heavy and unstable (also poor torque for starting from 0mph).

Light weight is critical re: lifting out of boot. Trike layout. Im using an 8inch pneumatic tyre directly mounted to a front hub motor. Torque by far most important so using a geared motor. Max rpm 170-200 is adequate (speed limit for mobility scooters is 4mph / 6kph). Obviously no pedals so no PAS needed. Must be able to start from 0mph (throttle only). Simplest possible interface (ideally on-off, throttle and brake only).

Drive train is intended to be front AKM Q75SX 36V 250w with disc brake. I would rather avoid an LCD display (I'm aware KT controllers can run without one) as I have a separate lithium battery meter.

Few questions:
1 - would it be easier to use a 36V BLDC e-scooter controller if none of the other ebike controller features are needed? Or just use KT and no LCD (after initial setup).

2 - if using KT controller with no LCD, can on-off be as a switch on one of the jumped LCD cables to switch on the controller?

3 - how does throttle cruise control work for KT without LCD?

All thoughts welcome.

Cheers, Joe.

 

[comfybob420]

I'm working up my idea on a lightweight mobility scooter for myself since I've sustained serious leg injuries. I have a Segway Ninebot folding scooter that can start at 0mph. Weighs in at 30 lbs. I found a drywall/slab dolley that I believe with little modification, could replace the rear axle coming in at 19 inches wide with 8 inch pneumatic tires and according to the specs it weighs 16 lbs.
If it works out, I'll have a mobility scooter less than 50 lbs that fits in a trunk. And total cost less than $400
Will post my results

 

[MxusMick]

I harvest parts off kids play cars and kids scooters all the time, the axles, switches, motor.A brushed motor would not need a controller, those hoverboards have powerful 3 phase motors as well.A hoverboard masterchip is designed to go real slow, you want that, if you put a hoverboard motor on an ebike controller, way too fast.

 

[SlowCo]

 

[fill]

Just my take..

1) If the requirements above are all a headless KT controller should be ok.
2) yes switching the display pins 1,2 battery voltage and 'lock' will provide on/off but a battery isolation switch is also a very good idea in addition.
3) dunno, But some KT controllers come with a wiring h/w solution to enable/disable cruise control, 2x blue wires with a loop connector to enable/disable cruise control as discussed in this pedelec-uk forum thread no details there on how to specify this feature however.

good luck with the build..

 

[Chalo]

Im using an 8inch pneumatic tyre directly mounted to a front hub motor.

Drive train is intended to be front AKM Q75SX 36V 250w with disc brake.

How do you propose to inflate that 8 inch pneumatic tire?

 

[Chalo]

I harvest parts off kids play cars and kids scooters all the time, the axles, switches, motor.A brushed motor would not need a controller, those hoverboards have powerful 3 phase motors as well.A hoverboard masterchip is designed to go real slow, you want that, if you put a hoverboard motor on an ebike controller, way too fast.

Also a hoverboard based solution could use vector steering, with a caster for the front wheel.

 

[surgicalfpv]

I can relate when it comes to needing a scooter that is easy to load into the boot or trunk of a car... Most options are simply too heavy to dead-lift. That being said, there is a model that has a unique feature about it called the GB120 made by Golden Technologies in the USA. I believe they have dealers in Europe too. This model is a fold-flat model that you can stand up on its kick stand, then tilt the front two wheels so that they rest on the bumper of your car, once its positioned this way, you can grab the handles on the rear of the scooter and roll it into the boot/trunk of your car. This makes it soooo much easier to work with! This video below does a great job at explaining it. This guy makes a ton of DIY videos about mobility devices. See for yourself, and let me know what you think, its been a real life-saver for me. I've had 3 knee surgeries and cannot stand or walk for long periods of time.

I use a few different mobility devices, I have a GB120 scooter which I think is the best option for travel if you are 250 lbs or less. It's airline approved and cruise-line approved. It folds flat into a very compact shape (on 12" tall when folded) which allows me to store it almost anywhere. This is one of the lower priced travel scooters with a lithium battery that I could find after doing loads of research.

I also have a Baja Mobility Bandit which is my "off road" option. This thing is a BEAST! It handles gravel, sand, dirt, mud, inclines, and all sorts of obstacles. It's pretty fast for a mobility scooter too. The only con is that its heavy and hard to take apart. If you can manage to lift about 50 lbs., it breaks down into 5 pieces and can fit into almost any car though. I don't really know of any other powerful off road models that can do that. Now the Baja Bandit is not a cheap option, but it has ALL the bells and whistles.

 

[E-HP]

Im using an 8inch pneumatic tyre directly mounted to a front hub motor. Torque by far most important so using a geared motor. Max rpm 170-200 is adequate (speed limit for mobility scooters is 4mph / 6kph). Must be able to start from 0mph (throttle only).

Drive train is intended to be front AKM Q75SX 36V 250w with disc brake. I would rather avoid an LCD display (I'm aware KT controllers can run without one) as I have a separate lithium battery meter.

All thoughts welcome.

As mentioned, not sure how you'll mount that tire and make it work. Regardless, based on your modest speed requirements, I believe motor choice and winding is probably most important decision. It's best to get the slowest wind, highest gear reduction motor you can find.
Using the Shengyi motor as an example (I believe the Std wind is 201 rpm at 36V, but just using this for an example), you can see by choosing a winding that close to your top speed requirement, vs one with a faster wind, you can have almost double the torque at the start, all other things being equal (46Nm vs 24Nm). The problem with these small geared motors is that the nylon gears can only take so much before they strip out. In the example below, phase amps are limited to 20A (reading a few threads, others seem to recommend keeping the phase amps low to avoid stripping gears).
Anyway, you'll need to think through how you'll get the 8" tire to work first, which may limit your motor choices.
Something like the wheelbarrow motor sold by Grin may be an option, but I don't know much about it. It has a super slow wind and fits an 8" tire.

Geared Wheelbarrow Motor, No Tire

Electric Wheelbarrow motor with high 30:1 Gear Reduction Ratio, (3.1 RPM/V). Uses common 4.00-8 Tire size.

ebikes.ca

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

Wheelbarrow motor:

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca