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  • Scooter project

    One of our sons has a neuro-muscular condition that limits his mobility. He can walk and get around on his own, but his muscles tire, weaken, and hurt before very long. When we go out to a museum or someplace similar that requires a lot of walking, he uses a wheelchair, but even propelling himself in that wears him out. And of course the wheelchair is not very good once you get off of reasonably hard, flat surfaces.

    So one of the things I've been working on is an electric scooter for him to to get around on. Yeah you can buy them, but no 11 year old wants to cruise around on an "old lady scooter" (his words...). Plus most of them are heavy/bulky and don't do so well off of hard surfaces. We finally got to do some extended road trials yesterday:

    A pic of it:




    And a couple of (sorta large) videos:






    Not bad for a first outing. Still needs some refinement (like brakes...) but it went great even on the grass. It will easily negotiate most of the trails that we walk down to go fishing.

    This is still "prototype" stage, but am pretty happy with the result. It breaks down into smaller pieces without tools for getting into and out of cars and such. Going to invest some bucks for a much lighter battery pack that has equal or better capacity than the two sealed lead-acid bricks that are on there now. They near double the weight of the scooter.

    Of course he also wants a built-in IPOD dock, and a winter camo paint job.

    If we get any dry weather over the weekend I'm going to strap the GPS to it for speed and distance/charge tests.

    It is hard to convey how thrilled he is with this thing. He just zipped back and forth across the park for over an hour, a big stupid grin on his face. Tooling along like that must be a great feeling for a kid who never was able to even ride a bike.

    I can post some better pics of the scooter and how it breaks down when I get back out to work on it some more.

    Thought some of you might find this interesting.

    -Al

  • #2
    Way cool Al,
    Who wouldn't want one of those

    Goes at a pretty good clip to, maybe too fast ?

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    • #3
      Cool work Al.
      So what are the details on your existing batteries? How many AH? What's system voltage?
      With that we can make some suggestions. For max energy density some form of lithium is in order. Once we know the details I might have some novel ideas.
      Dave

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      • #4
        Outstanding! I know exactly how he feels. My condition has precisely the same effect.

        I presume you are using a commercial motor controller. You can get ones that have a braking feature built in. Motor braking is very effective. edit: It looks to me that the controller has a braking feature.

        It's 24 volt and the motor is 350 watts. The batteries are about 20 amp hour VRLA type.
        Last edited by Evan; 07-10-2010, 10:10 AM.
        Free software for calculating bolt circles and similar: Click Here

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        • #5
          That's teriffic! He looks like a fine young man as well!

          I'd much rather have something that my father had something to do with, too!

          Could you post the details about the motors? I presume that it's two 12's in series for 24VDC. I need to do some more work on a reverse for my Harley sidecar and what you have there looks like it would be perfect.
          Last edited by gnm109; 07-10-2010, 10:23 AM.

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          • #6
            that is very nice, great build, way to go....like Ken said who wouldn't want one. Must have been a great feeling making such a useful thing for you son.
            in Toronto Ontario - where are you?

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            • #7
              Thanks, guys.

              I know Evan has spent lots of time researching this sort of stuff, he was pretty close on the hardware.

              Some details:

              Frame is 6061 Al rectangular tube, mostly MIG welded construction, thanks to the guys on the welding forum here. The three major parts interlock as it is assembled, so no tools or fasteners are needed to stow it for transport. The frame, motors and controls weigh a bit under 30 pounds. The present batteries are around 26 pounds.

              System is 24V, two 12V, 18 AH SLA. They were picked up used (free) and are of unknown overall condition, but do charge normally and have decent running life. We have not run them to cutoff yet, so I do not know the ultimate range at this point.

              Motors are two 24V 250W PM electric scooter motors. These are the ones:
              https://www.electricscooterparts.com...ode=MOT-24250B

              These seem to generate plenty of power. It moves me around (at over twice his weight) without problems.

              Correct on the controllers, Evan, I used these:
              https://www.electricscooterparts.com...Code=SPD-24250

              I used one for each motor controlled by a common throttle signal.

              Evan, I don't know if these controllers have dynamic breaking built in. I got them mostly because they were a cheap and expedient way to see how this thing was going to work. They do have a "brake" connector on them which I presumed served only to cut power to the motor when a mechanical brake is applied. I may have that wrong. Do you know any more about these? I'm certainly not adverse to switching controllers for better capability. Dynamic braking would be a much simpler alternative to mechanical brakes, though I have some ideas how I might implement them.


              Ken, It is on the edge of being "too fast" perhaps, but he is a pretty sensible kid and not overly given to doing stupid/dangerous stuff. On the other hand, I believe it is not such a bad thing for young boys to have at least a bit of opportunity to push the envelope a bit, so I discarded my original plan to add a speed limiting to the controls. Of course once he got a feel for the way it ran, one of the first things he did was to race his little brother.

              gnm109 - The motors are 24V units, so likely won't be so good for your project. Electric reverse for a sidecar sounds like a cool and unique project.

              And thank you, you are correct, he IS a fine young man. He is in near constant state of pain and is often near exhaustion from doing nothing, has endured several years of very uncomfortable medical tests, but NEVER utters a complaint about anything. He is always in a good mood and very upbeat. In many ways he is one of the toughest people I know.

              Thanks for the comments and any additional ideas, guys. Like all such projects, it is never REALLY done.

              -Al

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              • #8
                I there was a contest for "Best Project" you would win hands down just because of that no so silly grin !!!!!!!!!

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                • #9
                  Awsome design, I really like how you kept most of the weight/stress over the back and front wheels, so that the frame could be minimistic.

                  Some of that wiring in the back looks like it could be secured a little better.. Any vehical has vibration issues to contend with loosening all the bolts and connectors.

                  Zip ties work well for the wires, As well as giving it a couple once overs with a wrench to tighten any bolts working there way loose (Usally, once tightened enough this stops..)
                  Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                  • #10
                    Next thing you know, he'll be wanting (and you'll be building) something like this... No "old lady scooter" stigma there!
                    Location: Saskatoon, Saskatchewan, Canada

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                    • #11
                      Originally posted by Black_Moons
                      Awsome design, I really like how you kept most of the weight/stress over the back and front wheels, so that the frame could be minimistic.

                      Some of that wiring in the back looks like it could be secured a little better.. Any vehical has vibration issues to contend with loosening all the bolts and connectors.

                      Zip ties work well for the wires, As well as giving it a couple once overs with a wrench to tighten any bolts working there way loose (Usally, once tightened enough this stops..)
                      Thanks, I did try to keep the weight back over the rear wheel, as you note. The seat post is angled forward like that in an attempt to shift enough weight forward to reduce the tendency to do wheelies. Pleanty of low-end torque with these motors. That seems to have worked as planned.

                      That is a fair observation on the wiring, it will be done properly. This was just the quickie setup to keep stuff out of harm's way so we could test the overall concept. I plan on doing a much more integrated setup on the wiring once all of the details are ironed out.

                      Right on on the vibration too. There are not many threaded fasteners on this, and I used split lock washers and removable loctite on most of them. A couple that I forgot were on the bottom of the seat. The nuts vibrated off of two if those bolts yesterday...

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                      • #12
                        Originally posted by Arcane
                        Next thing you know, he'll be wanting (and you'll be building) something like this... No "old lady scooter" stigma there!
                        Yikes! I better hope he never sees that or I WILL be building one!!

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                        • #13
                          Thats a nice scooter you made, im sure others will see it and want one.
                          Looks like if it could hold a fat old man and a set of golf clubs then I would like one.

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                          • #14
                            That's one of the coolest shop made scooters ever. I was amazed at the speed. I'd be interested to know the top speed when you find out. I use a power wheechair that's rated at 7.5 MPH (motors) and (batteries) for 30 miles on a 5% incline with a 250 lb person abord. I don't weight near that much so it runs forever.

                            I totally agree with him on the IPOD dock....it's a must have....
                            Last edited by Kenwc; 07-10-2010, 04:22 PM.

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                            • #15
                              Unfortunately no dynamic braking on those controllers. They will shut off the power when brake is applied. You can take advantage of that to rig your own dynamic braking by using the brake switch to operate a horn relay(s) wired to just one of the batteries for the relay coils. Use a separate relay for each motor. Wire it so that when it is closed it applies a resistor across the motor terminals. This will give pretty good braking and won't overload the controller if it happens to be in circuit when power is on. (shouldn't happen)

                              The resistors can be a couple of 55 watt headlamp bulbs. The motors will generate about half the rated 24 volts maximum so 12 volt bulbs shouldn't blow. They can be used as brake lights too. If the braking effect isn't enough just add another bulb in parallel.

                              I will have a look around online to see if I can find a reasonably priced controller with dynamic braking.

                              I didn't see the other motor or I would have revised my estimate of the wattage downward. I do think it goes a bit fast and he will probably flip it at some point, hopefully on the grass.
                              Free software for calculating bolt circles and similar: Click Here

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