Speeding up an electric wheelchair

[prestosterone]

I've been bumming around the forum looking for advice but I've come to a bit of a stand-still on a project I'm working on.

I'm attempting to increase the top speed on an older electric wheelchair, nothing significant just 5 or 6mph faster, but I'm really at a loss on how to move forward.

Some people have said the motors are capable of much more speed but the voltage is capped (likely through the controller) and a simple rewiring could get around this problem and deliver more kick to the motors. Another option that people bring up is to simply put bigger wheels on the chair, but that appears to also require some ratio work to make it work properly.

I was just wondering if anyone had done anything like this before, had any experience with modifying wheelchairs, or could recommend where I might find someone who would know/be interested in helping out with this type of project.

Anyone?

 

[KieranM]

you could rewire it so that it bypasses the speed controller, so its direct current flowing from the battery to the motor, but first check the voltage of the battery's and the motors

 

[anderkart]

Some people have said the motors are capable of much more speed but the voltage is capped (likely through the controller) and a simple rewiring could get around this problem and deliver more kick to the motors.

You could run a simple test to see if your controller "caps" the voltage by connecting a volt meter to the motors (+/-) inputs, then run it full speed while under load, meaning with you in it.

Then do the same test with your volt meter connected directly to the batteries output connections. I'd guess that if this voltage drop test found more than about a 1 volt drop, your controller would in fact be capping/reducing and you could install some other type of controller that delivered full power. (at the same time you might be able to add yet another battery connected in series to really get that motor spinning

 

[KieranM]

bare in mind that adding batteries will change the chairs centre of gravity.

 

[Kaptain Krunch]

bare in mind that adding batteries will change the chairs centre of gravity.

if its mounted low it wont matter.

 

[Linksep]

Bigger wheels and/or tires don't need ratio changes, they are the ratio changes.

 

[anderkart]

I was thinkin If the additional battery was mounted low, centered and forward it might just help keep all that new found power from popping wheelies.
Ahhh... better install some wheelie bars anyway, they'll look cool even if not needed

 

[KieranM]

as far as i can remember i think all wheelchairs come with the safety bars for doing wheelies accidentally

 

[prestosterone]

Yea the wheelchair already has tip bars on the back (most do) because it's already not the most balanced. So if I was going to add another battery, would I wire this into a series with the other 2 batteries currently on the chair or would I have to route it through another way to avoid the controller?

 

[anderkart]

Simply adding another battery (connected in series) with your current controller might just give you the added performance your seeking, or I suppose the higher voltage/amperage could just as easily end up damaging the controller and/or other components as soon as you hit the switch.

I'd imagine a wheelchair controller system is quite a bit different than one someone might install on a go kart cause it has to operate each drive wheel separately for steering. I've never tinkered with one, does yours have a separate motor for each drive wheel? (or does it just have 1 motor and achieve its steering from some other method?)

Post the brand/model and maybe we can find an online schematic to see what all were dealing with here.

I'm still not sure if your handicapped or just wanna build a faster toy, but if its the later have you considered using a gas engine instead of electric power?
Check out some of these videos: http://www.youtube.com/results?search_query=gasoline+powered+wheelchair&search_type=&aq=f

 

[prestosterone]

It's one of these: http://www.maddenspharmacy.com/arrowaction.html

It's called an Action Arrow Storm Series. It uses 2 motors, one on each rear wheel, controlled through a joystick. I want to keep the electric motors because they're quiet. As I said earlier, I'm not looking for a HUGE performance boost, rather just a few mph faster.

 

[prestosterone]

Oh I should also point out it's for indoor use, another reason for not wanting a gas motor. This also means I won't necessarily need as much torque, as it will be driven on smooth surfaces and not on say grass or loose dirt/gravel

 

[Linksep]

Just put taller tires on it and that will increase your speed equal to the % increase in tire size.

i.e. If you go 10 MPH on stock 10" tires you'll go 14 MPH on 14" tires (40% bigger tire=40% more top speed). That assumes your motors aren't already putting out max torque at top speed (unlikely).

 

[prestosterone]

I measured and the wheels, from ground to the top of the rubber is 13 inches, meaning I'd need about 18-20 inch wheels to get the desired speed boost. Where in the world would I find 18-20 inch wheels? Any ideas?

 

[Linksep]

Well, I just looked at the Invacare website (manufacturers can be a great source of info), by looking at the online parts catalog for your chair it appears your chair was at one time offered with a "Performance Plus Package" that apparently consisted of a 7-25/32" driven pulley instead of the standard 10-17/32" pulley. The part # for the performance pulley is 1007102. According to the website the pulley is discontinued and it says call 1-800-333-6900 Extension 3722 for more info.

If you can't possibly locate the performance pulley, you might be able to get this 20" tire from Northern Tool & Equipment to work; or maybe you could do the performance pulley and 20" tires to really make that thing haul butt (relative to other electric wheelchairs).

While 5-6 MPH faster doesn't sound significant when you say (or type it), remember... that's just a shade under twice as fast as the chair is now.

 

[prestosterone]

Great find on those tires, thanks! Hopefully I can find someone who can modify them so they can connect to the specialized hubcaps on the chair.

In terms of the pulley, I was poking my nose around the catalog and couldn't find the performance pulley you mentioned. Do you happen to have a direct link?

 

[kpfx.ca]

Just stumbled across the conversation... doing relatively the same project with a heavy duty front drive Jazzy.

Wouldn't recommend changing the 24volt to 48 in series... you'll fry the controller "electronics"... There are some wheel chair techs out there that may hack the controller for you...

I just ordered in some ATV tires & rims... 21x7" 10x5" rim- should increase the speed 40%.... over the stock 15x4" ~ will have to make some adapter plates.

planning to squeeze the frame width/ turning the batteries side ways to compensate for the extra width... got a light weight seat.

curb killer