Q128 alternatives?

Hi, I'm currently using a 48v Q128 wound to 201rpm which is in a 20 inch wheel to power my wheelchair trike thing , I'm building another and was wondering if there was a more energy efficient way of getting the same sort of torque as the q128 gives without spending a fortune more and would other options be as reliable, thanks in advance for any help

I think the consensus is the akm-128 (and it's clone the q128) are among the best hub motors. What controller are you using and what is the maximum current ? Using the KT controller and it's PAS levels definitely maximises the range afaic. The other option would be mid motor but I'm sceptical it will be more efficient. What problems are you having ?

If you can tolerate a smaller wheel, then a 16" rim will be 25% slower at same rpm, and so give more torque at any given speed.

 

If a serious amount of redesign is possible, and an even smaller wheel would work, and speed is not important, then the Bafang wheelbarrow motor might be worth a look.

 

I have not tried any of the above myself.

You could run it at 36v to convert it to 155 rpm if you need less speed, or you could go right down to 24v to get 108 rpm. 155 rpm in a 20" wheel would give about 9 mph at 36v. You can compensate for the loss of power and torque by increasing the current. A 48v motor at 15A gives the same power and torque with 20A at 36v. The only difference is the lower maximum speed. The Q128H can comfortably handle 25A.

Thanks to all for the help so far, It would have probably helped you if I had given you an image to begin with, so it will be my only form of propulsion so needs to be strong enough to withstand that, I want to use one of the 48v or 52v battery's I already have, it has to be 20 inch as it is v brake only. I'm currently using a s-ku95 controller with a led810 display, it would be good if I could use the same set up but not essential.

Also are there any particular dealers best to buy from

 

 

 

Forgot to mention I have 125mm between drop outs so can put spacers on for a 100mm front hub but unfortunately can't quite fit a rear hub on there.

The more I say the more this sounds like a bodge job but it has done 5-8 miles daily for 4 or 5 years on rough terrain.

Edited December 16, 20241 yr by Matthew Hutchinson

So is this a self built add-on to a normal wheelchair, or adaptation of a commercially available add-on?

 

Either way an impressive machine that serves its purpose.

Forgot to mention I have 125mm between drop outs so can put spacers on for a 100mm front hub but unfortunately can't quite fit a rear hub on there.

The more I say the more this sounds like a bodge job but it has done 5-8 miles daily for 4 or 5 years on rough terrain.

What are you trying to improve?

So is this a self built add-on to a normal wheelchair, or adaptation of a commercially available add-on?

 

Either way an impressive machine that serves its purpose.

It's an adaptation of a product from the early 80s , they were actually on tomorrow's world if you are old enough to remember it, I added a variable rear axle using bmx steering stems to hold it on so the axle is now behind the wheelchair bringing more weight in to the front wheel, removed the original 150 watt wheel and gubbins and for the q128 and then improved the way to connect it to the wheelchair because I can be quite rough and was breaking the aluminium set up so remade it in steel.

Invention proves a real winner

"A DISABLED woman in Barnoldswick has a new found sense of freedom thanks to an invention first highlighted on the television programme Tomorrow's World.

Forty-seven-year-old Jeannie Crangle, of Rainhall Crescent, is the first person in West Craven and even the Pendle district to own a Powertrike, a device that motorises wheelchairs.

Jeannie has been in a wheelchair for the past three to four years and before the Powertrike had to rely on family and friends to help her manoeuvre around the town or on her mobility scooter."

https://www.thetelegraphandargus.co.uk/news/8017557.invention-proves-a-real-winner/

 

Pdg powertrike "inherently dangerous" says judge

THIS pair of convicted fraudsters boast they can give disabled people their "freedom".

"After four weeks of repairs Mary, from Barnsley, tried it again. "The bike nearly killed me," she said. "As I approached a crossing it would not stop.""

https://www.mirror.co.uk/opinion/money-opinion/p-s-investigates/pdg-powertrike-inherently-dangerous-says-533930

I just spoked up an AKM128H into a 26" wheel, These motors have gotten more expensive since I bought my first one in 2019. I paid something like $130 USD shipped then. This most recent one cost me $175 USD shipped. Just a bare motor, Sapim spokes and a rim were almost $100.

 

The nice thing is that the 135 mm rear motor has a pair of spacers held with a hex bolt under the freewheel to set the O.L.D. at 135mm. WIthout a freewheel, you could trim the spacers and use the rear for your 125mm front fork.

 

There are less expensive hub wheel kits available on aliexpress but I stubbornly want the Aikemas.

I'm building another and was wondering if there was a more energy efficient way of getting the same sort of torque as the q128 gives

 

I don't really understand, do you need a longer range? what makes you suspect your current solution isn't energy efficient ?

I'm guessing more time spent at low speeds, well below peak efficiency, than in a bike installation.

Invention proves a real winner

"A DISABLED woman in Barnoldswick has a new found sense of freedom thanks to an invention first highlighted on the television programme Tomorrow's World.

 

Forty-seven-year-old Jeannie Crangle, of Rainhall Crescent, is the first person in West Craven and even the Pendle district to own a Powertrike, a device that motorises wheelchairs.

 

Jeannie has been in a wheelchair for the past three to four years and before the Powertrike had to rely on family and friends to help her manoeuvre around the town or on her mobility scooter."

https://www.thetelegraphandargus.co.uk/news/8017557.invention-proves-a-real-winner/

 

Pdg powertrike "inherently dangerous" says judge

THIS pair of convicted fraudsters boast they can give disabled people their "freedom".

"After four weeks of repairs Mary, from Barnsley, tried it again. "The bike nearly killed me," she said. "As I approached a crossing it would not stop.""

https://www.mirror.co.uk/opinion/money-opinion/p-s-investigates/pdg-powertrike-inherently-dangerous-says-533930

To be fair it's not something I would give to an old person, they are quite tippy, not something that bothers me, as much to my wife's annoyance I'm constantly riding on its side on two wheels because it's fun, it's like anything you just have to be aware of it's limitations but it's allowed me to go places I could never go before, it's a lot of fun and I can see people looking at it enviously because it looks fun unlike a standard mobility scooter

I don't really understand, do you need a longer range? what makes you suspect your current solution isn't energy efficient ?

That's a good point I'm beginning to think there is no point in changing, I thought that as it had been a few years things might have moved on and I was using something old and clunky but TBF I think I might just order another q128 and stick with that

I'm guessing more time spent at low speeds, well below peak efficiency, than in a bike installation.

 

But a 201 rpm motor in a 20" wheel won't go very fast ?

But a 201 rpm motor in a 20" wheel won't go very fast ?

Roughly 5/7 as fast compared to 700c wheel at any given rpm.

 

So in a bike situation, maximum assistance speed drops to about 11mph, and the recommended 'don't go slower than' speed of about 8mph drops to about 5.5mph. Quite fast for a wheelchair!

 

So could be spending a fair proportion of time below 50% efficiency. For shortish journeys with a biggish battery, unlikely to cause failure type issues, but eating more battery than a motor operating in its happy place.

I can't offer any tech advice [mention=19220]Matthew Hutchinson[/mention] but just to say I love your adaptation on the trike and 'getting out there' - bravo sir