DC motor speed control/ Electric wheelchair
Discussion
Hello,
I am trying to work out if I can use geared 12V motors from an electric wheelchair to drive a child’s car (homemade).
It’s a Toylander build, and the stock motors are two 12V 180W items from Parvalux. Since these are quite pricey, I had hoped to use used wheelchair motors instead, but it seems hard to find data on their power, current, RPM. Does anyone have any experience with such things? Are they gutsy enough to accelerate and push a plywood 1/2 scale Land Rover and an adult along at 4mph?
I’m also wondering if I can make my own speed controller using a pedal such as this:
https://www.amazon.co.uk/Brake-Vehicle-Accelerator...
...as an input.
Is this fanciful or achievable? I’ve done some electronics stuff in the past (school and university) - not for a while but I’m not a complete beginner. Is there any way I can use something light duty like this to control two 180W motors, or am I just going to wish I’d spent ~£650 on new motors and speed controllers?
Any suggestions or guides for electronics welcome.
I am trying to work out if I can use geared 12V motors from an electric wheelchair to drive a child’s car (homemade).
It’s a Toylander build, and the stock motors are two 12V 180W items from Parvalux. Since these are quite pricey, I had hoped to use used wheelchair motors instead, but it seems hard to find data on their power, current, RPM. Does anyone have any experience with such things? Are they gutsy enough to accelerate and push a plywood 1/2 scale Land Rover and an adult along at 4mph?
I’m also wondering if I can make my own speed controller using a pedal such as this:
https://www.amazon.co.uk/Brake-Vehicle-Accelerator...
...as an input.
Is this fanciful or achievable? I’ve done some electronics stuff in the past (school and university) - not for a while but I’m not a complete beginner. Is there any way I can use something light duty like this to control two 180W motors, or am I just going to wish I’d spent ~£650 on new motors and speed controllers?
Any suggestions or guides for electronics welcome.
Parvalux make wheelchair motors - see https://www.parvalux.com/electric-motor-applicatio... for info from them, including voltage, power and speed (rpm). The Toylander motors look like Parvalux wheelchair motors of a particular spec, very similar to some of those listed anyway. If you can find something suitable/similar from a wheelchair repair shop, eBay or somewhere else for a better price, then with appropriate fixing/mounting points they could probably be used.
For control you'll also need a speed/motor controller to go between the pedal and the motor(s). The pedal alone is not enough to control the motor(s). The Toylander control box is https://www.toylander.com/speed-control-box (they also list one with a shiny aluminium pedal). The control box is the bit that actually controls the motor, based on input from the pedal.
DC motor control modules come in lots of varieties, see (e.g.):
https://www.pololu.com/category/10/brushed-dc-moto...
https://www.robotshop.com/uk/brushed-motor-control...
https://uk.rs-online.com/web/c/automation-control-...
And whatever else you can find on eBay, Alibaba, etc.
Or you could build your own, (probably) using a PWM generator and MOSFET based H-bridge.
Whatever your purchase/build conclusion, you'll need one with a high enough current rating for your chosen motors (180W at 12V would be 15A (minimum) per channel/motor; other motors could need more (or less)) and able to interface to your chosen pedal (that Amazon pedal looks from the questions like it's a Hall Effect Sensor (HES) which needs +5V and outputs an analogue voltage based on pedal position).
There are various write-ups from people that have done it (or similar) (examples) - try https://www.google.com/search?q=wheelchair+motor+s... for more:
https://www.instructables.com/Electric-Wheelchair-...
https://www.allaboutcircuits.com/projects/building...
https://www.servomagazine.com/magazine/article/har...
It is all technically feasible to do yourself, if you've got the time, inclination and tools. If you're short on any of those, buying the Toylander stuff - that's guaranteed to all work together - might be easiest.
For control you'll also need a speed/motor controller to go between the pedal and the motor(s). The pedal alone is not enough to control the motor(s). The Toylander control box is https://www.toylander.com/speed-control-box (they also list one with a shiny aluminium pedal). The control box is the bit that actually controls the motor, based on input from the pedal.
DC motor control modules come in lots of varieties, see (e.g.):
https://www.pololu.com/category/10/brushed-dc-moto...
https://www.robotshop.com/uk/brushed-motor-control...
https://uk.rs-online.com/web/c/automation-control-...
And whatever else you can find on eBay, Alibaba, etc.
Or you could build your own, (probably) using a PWM generator and MOSFET based H-bridge.
Whatever your purchase/build conclusion, you'll need one with a high enough current rating for your chosen motors (180W at 12V would be 15A (minimum) per channel/motor; other motors could need more (or less)) and able to interface to your chosen pedal (that Amazon pedal looks from the questions like it's a Hall Effect Sensor (HES) which needs +5V and outputs an analogue voltage based on pedal position).
There are various write-ups from people that have done it (or similar) (examples) - try https://www.google.com/search?q=wheelchair+motor+s... for more:
https://www.instructables.com/Electric-Wheelchair-...
https://www.allaboutcircuits.com/projects/building...
https://www.servomagazine.com/magazine/article/har...
It is all technically feasible to do yourself, if you've got the time, inclination and tools. If you're short on any of those, buying the Toylander stuff - that's guaranteed to all work together - might be easiest.
Thanks for the replies. It is decades since I watched Robot Wars, but I didn’t know that.
Curly, thanks very much. I can’t believe of all the things I’ve searched, I didn’t put in “wheelchair motor speed controller”. I had got as far as watching people rig up MOSFETs and potentiometers on YouTube, but hadn’t searched for the most obvious thing. I’ve only started looking at wheelchairs recently - I was originally looking at mobility scooters, but a local repair shop sent me down the wheelchair route, so separate motors instead of a transaxle.
I hadn’t expressed myself very well, as I knew you couldn’t just connect the pedal to the motors, but I wasn’t really sure how to work out what you could plug in to the ‘magic box’ of the speed controller, and what you couldn’t. Looking at the different controllers available, it suddenly seems more reasonable that TL are charging what they are for a speed control unit, as some of the ones on your links are big money, presumably for a higher specification that I haven’t yet understood the need for.
I had to google what PWM was, and it instantly brought a lot of long-unused physics/engineering flooding back! I’ll look through the guides from people who’ve done it - they look really useful. Thanks again!
Curly, thanks very much. I can’t believe of all the things I’ve searched, I didn’t put in “wheelchair motor speed controller”. I had got as far as watching people rig up MOSFETs and potentiometers on YouTube, but hadn’t searched for the most obvious thing. I’ve only started looking at wheelchairs recently - I was originally looking at mobility scooters, but a local repair shop sent me down the wheelchair route, so separate motors instead of a transaxle.
I hadn’t expressed myself very well, as I knew you couldn’t just connect the pedal to the motors, but I wasn’t really sure how to work out what you could plug in to the ‘magic box’ of the speed controller, and what you couldn’t. Looking at the different controllers available, it suddenly seems more reasonable that TL are charging what they are for a speed control unit, as some of the ones on your links are big money, presumably for a higher specification that I haven’t yet understood the need for.
I had to google what PWM was, and it instantly brought a lot of long-unused physics/engineering flooding back! I’ll look through the guides from people who’ve done it - they look really useful. Thanks again!
I built a Toylander, and there is one very clear benefit of using a transaxle and single motor, which I have seen happen a few times with my lad.
TBH, a Toylander is not massively stable, it has a highish CoG that will get higher as your child gets bigger. They are very heavy indeed with batteries, and if they get driven "off road", holes and dips in the ground can lead to the possibility of "rolling it", especially with over enthusiastic throttle and steering inputs.
With a transaxle, the second the inside wheel lifts, all power immediately goes to it, it spins, and all drive to the outside wheel is lost. Net result, the vehicle immediately stops, the inside wheel drops, and it accelerates slowly away. If both wheels are driven on separate motors, you have the equivalent of an LSD in a sports car, and the power stays on.
I suspect that a factory Toylander twin motor setup is not as fast as one built from an 8mph scooter, and the lower speed may well negate this issue, however having a bit more poke is sometimes welcome, and you can buy the bits cheaply. I bought a donor scooter for £50, complete with all electronics, and paid the EGIS controller manufacturer a similar amount to reprogram the ESC from a wig-wag potentiometer to a standard pot with a reverse.
Build thread here...
https://www.pistonheads.com/gassing/topic.asp?h=0&...
TBH, a Toylander is not massively stable, it has a highish CoG that will get higher as your child gets bigger. They are very heavy indeed with batteries, and if they get driven "off road", holes and dips in the ground can lead to the possibility of "rolling it", especially with over enthusiastic throttle and steering inputs.
With a transaxle, the second the inside wheel lifts, all power immediately goes to it, it spins, and all drive to the outside wheel is lost. Net result, the vehicle immediately stops, the inside wheel drops, and it accelerates slowly away. If both wheels are driven on separate motors, you have the equivalent of an LSD in a sports car, and the power stays on.
I suspect that a factory Toylander twin motor setup is not as fast as one built from an 8mph scooter, and the lower speed may well negate this issue, however having a bit more poke is sometimes welcome, and you can buy the bits cheaply. I bought a donor scooter for £50, complete with all electronics, and paid the EGIS controller manufacturer a similar amount to reprogram the ESC from a wig-wag potentiometer to a standard pot with a reverse.
Build thread here...
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Sorry for the delay in replying to you. That’s really useful feedback HardDrive, thanks. I am concerned a bit about the weight - how heavy would you estimate the finished vehicle is? I don’t have a garage but we have an outbuilding in the garden for storing it, however the door is slightly too narrow for it to go in on it’s wheels, hence the weight being an issue for moving it around. I considered routing some material away from the reverse of some of the parts which don’t seem structurally important, but I don’t imagine the weight reduction would be very noticeable.
I’ve seen your finished car on the build thread, but I’ll take a more thorough look. Yours looks brilliant! I doubt I’ll be able to achieve that level of detail though - it has taken me long enough to get all the plywood cut and tidied up.
I’ve seen your finished car on the build thread, but I’ll take a more thorough look. Yours looks brilliant! I doubt I’ll be able to achieve that level of detail though - it has taken me long enough to get all the plywood cut and tidied up.
Edited by Prawo Jazdy on Thursday 19th November 17:29
They are very heavy indeed. It's got to be getting on 80-90kg or so. Forget the routing idea, won't make any difference. You absolutely need to be able to get it on it's wheels wherever it needs to be, and for any big steps you will need ramps.
I'll weigh ours at some point and let you know.
I'll weigh ours at some point and let you know.
Thanks. It definitely won’t fit through the door frame on its wheels, and I don’t think storing it in the kitchen will be popular with anyone except my son 
I may have to create some sort of trolley that it can go on on its side to go through the door. It’s either that or build a kennel for it in the (rather small) garden
I may have to create some sort of trolley that it can go on on its side to go through the door. It’s either that or build a kennel for it in the (rather small) garden
Prawo Jazdy said:
It’s a Toylander build, and the stock motors are two 12V 180W items from Parvalux.
I think they used to use EMD motors, but they went bust, so that makes sense. As I understand it the single motor system uses one 12v motor on a single wheel, and the two motor system uses a pair of the same motors, wired in series using a 24v supply. Therefore you in effect get an electric differential, presumably with an amount of lsd action but not a lot? I don't know is this is how wheelchairs and the like use these motors but it would make sense if they do. I believe most scooters etc are 24v?
I believe they use a 4QD speed controller but I could be wrong. https://www.4qd.co.uk/product/dno/
Obviously the other way of doing it is the way larger mobility scooters and golf buggies etc do it, which is with a single motor and transaxle unit which use an actual differential.
Weighting up the options for our 2yo who is obsessed with 'Daddys yellow car' (Westfield) and Daddys green car' ( 1924 Austin 12).
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