Hello all,
I'm new here, and I'd like to get some input about motorizing an electric mobility scooter with a gasoline engine so my father can get the range he needs without having to worry about whether or not he'll make it home in the evening.
I'm an engineer. I have a mill and a lathe, and can build most anything. I've built engines, cars, and a Go-Ped ESR electric stand-up scooter that does 40mph.
However, I'm completely new to these motorized bicycle kits and am hoping you guys can help me understand how they work, and help me select a motor for the job at hand.
First, a bit about the mobility scooter. It is powered by a 1.5hp 24V electric motor that is coupled to a 17:1 transaxle and 10" tires. At 4000rpm (no load max), the motor moves the scooter approximately 7mph. I'm not looking to greatly improve speed; it would be fine if the scooter went no faster than this. 10mph would be great too; no more than that.
The electric motor shaft protrudes and is used for an electric drum parking brake. This will be removed, and a sprocket will be fitted such that I can attach the gasoline engine. The scooter will be fitted with a mechanical disk brake from a mountain bike.
So, I simply need an engine and sprocket ratio that will spin that sprocket 4000-5000 rpm. Judging by the amperage consumed by the electric motor when hauling a full load, I believe I need approximately 0.4hp on flat ground to do this.
I wish to bump-start or drag-start the gasoline engine. My father is unable to pull a cord like that.
I prefer four-stroke engines for obvious reasons. (noise, smoke, CARB approval, etc.)
I'm attracted to the Dax Titan 50cc 4-stroke and if that turns out to be a good candidate, I wonder if I can do the following:
1. Defeat the freewheel on the output sprocket; use a regular fixed sprocket instead.
2. Defeat the centrifugal clutch (turn a hub on the lathe, weld it in place)
3. Use the disengager to either engage or disengage the engines gearbox from the electric motor shaft discussed above.
4. To start, stop the scooter, engage the disengager (connect motors gear box to electric motor shaft), start the scooters electric motor moving (simply accelerate forward on electric power), thus drag-starting the engine. Once it starts, proceed on electric+gas, or just gas...whatever you please. There is up to 1.5hp worth of electric power available to apply backwards through the gearbox to drag-start the engine. I would not need to bump-start, it would drag start.
5. To stop, squeeze the disengager, apply the brakes. If you forget to disengage, the brakes will be enough to stall the engine (safety/emergency only). Usually, you'll just disengage and the motor will stay running. To use gas power again, it would be necessary to stop the engine and drag-start again, or perhaps you could get good at rev-matching things close enough where you could simply engage at a proper rev-match rpm. Would you destroy the disengager if you did this?
6. With the disengager disengaged, the electric scooter simply works as usual. The only additional drag is the sprockets which freewheel since they are disengaged from the motors gear box.
What's wrong with this idea? Can I drag start the motor in this manner or is the mechanical advantage of the gearbox too great to turn the motor over by back-feeding power into the gearbox in this manner?
Is there a 4-stroke kit better suited for this duty?
Should I be looking at 4-stroke engines without the gearbox? I could likely achieve 4000-5000rpm and get enough power even if I were to direct-drive or 1:1 sprocket drive.
If this won't work, then I always have the 2-stroke option...it looks to be simpler and more intended for this sort of bump-start application. I prefer the 4-stroke however. Quieter, more integrated, and an over-all nicer package given the application at hand.
Thanks for any help!
Sorry for such a long first post; I'm just excited and want to order the parts asap before I get too busy to finish this project for my dad.
I'm new here, and I'd like to get some input about motorizing an electric mobility scooter with a gasoline engine so my father can get the range he needs without having to worry about whether or not he'll make it home in the evening.
I'm an engineer. I have a mill and a lathe, and can build most anything. I've built engines, cars, and a Go-Ped ESR electric stand-up scooter that does 40mph.
However, I'm completely new to these motorized bicycle kits and am hoping you guys can help me understand how they work, and help me select a motor for the job at hand.
First, a bit about the mobility scooter. It is powered by a 1.5hp 24V electric motor that is coupled to a 17:1 transaxle and 10" tires. At 4000rpm (no load max), the motor moves the scooter approximately 7mph. I'm not looking to greatly improve speed; it would be fine if the scooter went no faster than this. 10mph would be great too; no more than that.
The electric motor shaft protrudes and is used for an electric drum parking brake. This will be removed, and a sprocket will be fitted such that I can attach the gasoline engine. The scooter will be fitted with a mechanical disk brake from a mountain bike.
So, I simply need an engine and sprocket ratio that will spin that sprocket 4000-5000 rpm. Judging by the amperage consumed by the electric motor when hauling a full load, I believe I need approximately 0.4hp on flat ground to do this.
I wish to bump-start or drag-start the gasoline engine. My father is unable to pull a cord like that.
I prefer four-stroke engines for obvious reasons. (noise, smoke, CARB approval, etc.)
I'm attracted to the Dax Titan 50cc 4-stroke and if that turns out to be a good candidate, I wonder if I can do the following:
1. Defeat the freewheel on the output sprocket; use a regular fixed sprocket instead.
2. Defeat the centrifugal clutch (turn a hub on the lathe, weld it in place)
3. Use the disengager to either engage or disengage the engines gearbox from the electric motor shaft discussed above.
4. To start, stop the scooter, engage the disengager (connect motors gear box to electric motor shaft), start the scooters electric motor moving (simply accelerate forward on electric power), thus drag-starting the engine. Once it starts, proceed on electric+gas, or just gas...whatever you please. There is up to 1.5hp worth of electric power available to apply backwards through the gearbox to drag-start the engine. I would not need to bump-start, it would drag start.
5. To stop, squeeze the disengager, apply the brakes. If you forget to disengage, the brakes will be enough to stall the engine (safety/emergency only). Usually, you'll just disengage and the motor will stay running. To use gas power again, it would be necessary to stop the engine and drag-start again, or perhaps you could get good at rev-matching things close enough where you could simply engage at a proper rev-match rpm. Would you destroy the disengager if you did this?
6. With the disengager disengaged, the electric scooter simply works as usual. The only additional drag is the sprockets which freewheel since they are disengaged from the motors gear box.
What's wrong with this idea? Can I drag start the motor in this manner or is the mechanical advantage of the gearbox too great to turn the motor over by back-feeding power into the gearbox in this manner?
Is there a 4-stroke kit better suited for this duty?
Should I be looking at 4-stroke engines without the gearbox? I could likely achieve 4000-5000rpm and get enough power even if I were to direct-drive or 1:1 sprocket drive.
If this won't work, then I always have the 2-stroke option...it looks to be simpler and more intended for this sort of bump-start application. I prefer the 4-stroke however. Quieter, more integrated, and an over-all nicer package given the application at hand.
Thanks for any help!
Sorry for such a long first post; I'm just excited and want to order the parts asap before I get too busy to finish this project for my dad.
