Electric Wheelchair Attachment - DIY

Hi,
we would like to share a build we were a part of - DIY electric wheelchair attachment.
On the market you can find 'ready to ride' solutions but most of them are slow (25km/h) and the range is not so long.

The concept was simple:
-50km range
-as fast as possible (but still safe at the same time) +/- 45km/h



We started with regular wheelchair and Rapid S-1100 SL ebike kit with 12,5Ah 48V battery:

• 1000W planetary geared hub motor

• 48V 22A controller

• 48V 12,5Ah battery ~673 Wh - Samsung 25R cells

https://ebikers.eu/en_GB/p/Rapid-S-1100-SuperLight-Conversion-Kit/45
https://ebikers.eu/en_GB/p/Battery-Guru-BG600-battery-12,5-Ah/42

Motor was laced into 20" fatbike rim with 4" tire



To make a frame one bike had to be salvaged - for headtube and fork









Frame and wheelchair are connected in 3 spots for safety reasons



Battery is shrink-wrapped so enclosure had to be designed and made



It was 3D printed with PLA and metal sheet was added to add durability and rigidity.
PLA has low melting point so in future it will be remade with ABS or PETG or fiberglass









It took only one night to print









First test (there is no headset, that is why everything is shaking)

[youtube]FNj1XO_sGhg[/youtube]

The frame still needs painting but for now everything works fine



[youtube]q9_CqwSwag0[/youtube]

The wheelchair wheels will be changed

Nicely done! My son, who is a quad, has had a davinci mobility attachment for a number of years but it has active pedaling also.

The way you have setup this one with the front end weight bias is going to work well for traction. My son’s has a bbs01 crankset for power and it isn’t optimal for traction.

That looks great! The test pilot seems to be enjoying it too. I bet you can get the front tire to spin if you slam the throttle.

How hard is it to detach the drive unit? Ideally you'd want this to be possible without getting out of the chair.

Bigwheel said:

Nicely done! My son, who is a quad, has had a davinci mobility attachment for a number of years but it has active pedaling also.

The way you have setup this one with the front end weight bias is going to work well for traction. My son’s has a bbs01 crankset for power and it isn’t optimal for traction.

Click to expand...

We also did a conversion with mid drive, we used TSDZ2. It might be easier to install for wheelchairs with active pedaling but as you said at cost of traction.

fechter said:

That looks great! The test pilot seems to be enjoying it too. I bet you can get the front tire to spin if you slam the throttle.

How hard is it to detach the drive unit? Ideally you'd want this to be possible without getting out of the chair.

Click to expand...

Agree, the perfect setup is when person can mount the drive attachment on his own.
At this moment you need an extra hand to detach the drive.

Let's say it is version 1.0 with room for improvements

As the op probably knows the level of injury will dictate what can or can’t be done in regards to this or any adaptive endeavor. For instance the one my son had could easily be used for self hook up but his level of injury won’t allow it and he needs assistance. But once it is in place it works well for him.

I use the tsdz2 on my emtb but in his case cadence sensing works better as it only takes crank movement to activate instead of pressure which he lacks ability for. So in his case the bbs01 works better.

But back to the traction issue I really want to convert his to a tdcm igh hubmotor and a schlumpf mtn drive. This would give him a more weighted front end and a wider range of gears, currently he has an 8spd. Alfine.

Keep up the good work there as there is definitely a market for this concept that isn’t being fully exploited. Most spinal chord injury hospitals have adaptive programs and would be a good place to reach out to if you are looking at this from a business perspective.

Cool! But that fender on the front wheel ain't going to help much if you hit water...

I would try and add a second brake disk on the other side of the motor. And use a separate brake lever on the right side for it. Now you have only one brake and if that fails at 45km/h...
Hopefully you did use the brake switch to the controller. You could also weld the clutch in the motor so you can use regen braking on the geared hub.

Unfortunately hub has only one mounting point for disc brake.
Yes, fender is a little bit too small


Upgraded wheels

Incredible job, and hope either it helps others by providing a template or you're able to market the concept. Also, (please forgive the diversion) bigwheel, I'm really impressed with what you've accomplished for your son.

Agreed, this is really cool. Nice welds, too.

After a few hundred kilometres of test.



The traction on loose terrain is ok, but still the motor can do the wheelspin at any speed :?
More weight on front axle is needed

Looks amazing. Great job. I'd suggest a smaller front wheel except your ground clearance is minimal now.

ebiker_pl said:

The traction on loose terrain is ok, but still the motor can do the wheelspin at any speed :?
More weight on front axle is needed

Click to expand...

Great to see it is being used and enjoyed!

Normally if a handcycle is used on a wheelchair then the wheelchair has a second rear axle to move the wheels further back and thus shifting the weight more forward to the driven handcycle wheel. See the explanation in this video from about 50 seconds:


[youtube]8rX84FUJbUI[/youtube]

If it is used mostly off road then a different tire might be a better choice also (enduro/trails/cross tire).

SlowCo said:

ebiker_pl said:

The traction on loose terrain is ok, but still the motor can do the wheelspin at any speed :?
More weight on front axle is needed

Click to expand...

Great to see it is being used and enjoyed!

Normally if a handcycle is used on a wheelchair then the wheelchair has a second rear axle to move the wheels further back and thus shifting the weight more forward to the driven handcycle wheel. See the explanation in this video from about 50 seconds:


[youtube]8rX84FUJbUI[/youtube]

If it is used mostly off road then a different tire might be a better choice also (enduro/trails/cross tire).

Click to expand...

Great video! Thanks for sharing, 2nd axle is the way to go!

That looks so good you could get mass market appeal.
You should put a solar panel on one and do the sun trip!

Update after first 1000km




No issues with the attachment so far, everything works really well!
The only upgrade we would like to make is add second battery or install bigger one.