# Using a Mobility Scooter Motor for a Riding Mower



## sameh4 (Sep 17, 2021)

I pulled an electric motor, complete with its gear box and electronic brake from a golden mobility scooter, which I found from Facebook Marketplace. I tested it and it seems to work fine, rotates in both directions.

The label on the motor is torn but the part number I found shows that it's an ASI Technologies Part number 10517, which leads me to believe it's this motor.

The riding mower I am using is the John Deere RX73. It was free from next door neighbor. The current engine is 9HP Kawasaki 290cc, it runs OK, it smokes a bit but it does run and mower moves fine, and deck engages.

This is my first conversion. My education and work is in software engineering and robotics, so I am probably one or two notches past newbie but not very far. 

Looking online at previous examples of mower conversions, they all recommend to use a separate motor for the mower deck, which makes perfect sense. So then the scooter motor would just have to drive the tractor.

I have many, many questions but I'll start with just a couple:

1. What calculations can I do to have an idea of whether this motor will be powerful enough to drive the mower. Based on the datasheet, I see that at Heavy load, it can produce 58 ft-lbs of force, with 114 RPM's, so does that mean it only has (58 * 114) / 5252 = 1.25 HP? Will that be enough to drive the mower (without the deck)?

2. I have not yet done the exact measurement, but it looks like the transaxle from the gear box (meaning the distance between the wheels on the scooter) is shorter than the width between the two wheels on the mower. I don't have welding equipment but I have used jb weld epoxy many times. Assuming it really is shorter, what are my options?

Thanks in advance!
Sameh


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## cricketo (Oct 4, 2018)

1. Yes
2. You either have to weld, or machine the extensions. If you were really lucky and diameter of the two axles matched, then you could extend using seamless pipe, cross drill and pin. I doubt you're that lucky. Get yourself a Lincoln "buzzbox" AC welder for $100 on Craigslist and start practicing.


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## brian_ (Feb 7, 2017)

sameh4 said:


> 1. What calculations can I do to have an idea of whether this motor will be powerful enough to drive the mower. Based on the datasheet, I see that at Heavy load, it can produce 58 ft-lbs of force, with 114 RPM's, so does that mean it only has (58 * 114) / 5252 = 1.25 HP?


Yes, that product of the torque and speed is only 1.25 HP. For confirmation, the spec sheets lists the output power under those conditions as 942 watts; a horsepower is 746 watts so that spec is 942 W / 746 W/HP = 1.26 HP.



sameh4 said:


> Will that be enough to drive the mower (without the deck)?


It sounds marginal to me, especially considering that it has to drive the weight of a person plus substantial battery across turf - scooters usually run only on hard surfaces, without cargo.

I think a similar axle with mounted electric motor from a golf cart would likely be more suitable. It would also be easier to narrow the golf cart axle than the widen the scooter axle, but I realize that the scooter axle is what's available.


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## sameh4 (Sep 17, 2021)

brian_ said:


> Yes, that product of the torque and speed is only 1.25 HP. For confirmation, the spec sheets lists the output power under those conditions as 942 watts; a horsepower is 746 watts so that spec is 942 W / 746 W/HP = 1.26 HP.


Thank you very much for the confirmation and clarification, exactly what I was looking for!


brian_ said:


> It sounds marginal to me, especially considering that it has to drive the weight of a person plus substantial battery across turf - scooters usually run only on hard surfaces, without cargo.


The intent behind this project is to autonomy, but you're making an excellent point.



brian_ said:


> I think a similar axle with mounted electric motor from a golf cart would likely be more suitable. It would also be easier to narrow the golf cart axle than the widen the scooter axle, but I realize that the scooter axle is what's available.


It's worth looking into it. I maybe able to find a junked Golf cart just like I found the Junked scooter.

Thanks again!


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## MattsAwesomeStuff (Aug 10, 2017)

At first I thought you were going to attach a blade to a functional mobility scooter, and you had my new favorite project.

Instead... w op w op (apparently a slur that gets censored). You're just using mobility scooter motors to power a blade.

Even a small lawnmower, with now power drive, is at least a few horsepower, no?

It's probably too small is my guess.

That said, you can probably overvolt it and with some added cooling fans or a scrap CPU cooling pipe thingy, I dunno, maybe it'll be fine. The community regularly feeds 120+ volts to 48v forklift motors to squeeze more power out of them. I would do something similar here. Good thing is you don't really need speed control for the mower, just full speed and let 'er rip. 1.25hp for drive is certainly plenty. It'd get you up to 50km/h 30mph if you wanted it to, all day every day.

Seems like the kind of project that's more fun to goof off with and get used to taking stuff apart and putting it back together, than necessarily the need to end up with a good finished product. If so, full speed ahead. It'll either work, or it'll be underpowered. No big deal.

Your admission cost is to take lots of pics, share your failures, and let us know if it worked out at all.


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## sameh4 (Sep 17, 2021)

MattsAwesomeStuff said:


> It's probably too small is my guess.


After reading several posts from you on this forum, I've learned your guesses are pretty accurate. 



MattsAwesomeStuff said:


> Seems like the kind of project that's more fun to goof off with and get used to taking stuff apart and putting it back together, than necessarily the need to end up with a good finished product. If so, full speed ahead. It'll either work, or it'll be underpowered. No big deal.


While I agree that it is a good learning project, and I could potentially end up with a nice platform for testing out autonomous software (as opposed to testing in simulator), I don't want to spend heaps of time if I am going to have to junk it later anyways.

What would be your suggestion in order to avoid this? Use a Golf Kart motor as @brian_ suggested? Would you suggest something else?

I have been thinking about the Golf Kart motor idea. The problem there is I don't have a hitch or a truck, so I can't get a junked one home and pull the motor then get rid of the scraps. I'd have to find a Gold Kart "junkyard" and ask them if they'll let me pull out the motor there. A quick look on ebay shows some pretty big price tags

What are your guys thoughts about all this? What would you do?


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## Electric Land Cruiser (Dec 30, 2020)

My buddy build an RC mower/plowbot out of a mobility scooter drivetrain. He used a walk-behind mower deck and it was well sized. I don't think a ride-on mower deck would work, too heavy.

He used an Ardupilot autopilot and FPV stuff and could plow or mow from his big screen TV. He never did get it working autonomously. Sensors and Ardupilot is a lot better now than it was back then 2015-2016.

Video of plowbot:


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## sameh4 (Sep 17, 2021)

Electric Land Cruiser said:


> My buddy build an RC mower/plowbot out of a mobility scooter drivetrain. He used a walk-behind mower deck and it was well sized. I don't think a ride-on mower deck would work, too heavy.


It's funny you say this because that was exactly my initial intent when I got the scooter motor. But then I saw my next door neighbor putting the riding mower into his truck, so I took it. 

I think I'll stick with the snow thrower, and once that's finished, I'll get back to the riding mower. It's pretty small and does not take too much space in the garage


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> Instead...
> You're just using mobility scooter motors to power a blade.
> 
> Even a small lawnmower, with now power drive, is at least a few horsepower, no?


Yes, much more than one kilowatt is needed, but most of the power goes into turning the blade, which will have a separate motor in this case. The mobility scooter motor is not to power a blade, it is only to propel the machine.


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## brian_ (Feb 7, 2017)

sameh4 said:


> The intent behind this project is to autonomy, but you're making an excellent point.


If you don't need it to be ridden by an operator, even at an early stage, that radically changes the requirements.


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## brian_ (Feb 7, 2017)

Electric Land Cruiser said:


> My buddy build an RC mower/plowbot out of a mobility scooter drivetrain. He used a walk-behind mower deck and it was well sized. I don't think a ride-on mower deck would work, too heavy.


The ride-on is too heavy for the scooter powertrain with an operator, but might be okay as an autonomous (or remote-controlled) vehicle. The advantages that I see of a small ride-on over a walk-behind are that it has a larger deck (so faster mowing) than typical walk-behind (the John Deere RX73 has a 30-inch deck), and that it has an easy place to mount a battery pack... but the scooter motor might still be inadequate.


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## sameh4 (Sep 17, 2021)

brian_ said:


> If you don't need it to be ridden by an operator, even at an early stage, that radically changes the requirements.


Thinking more about this: An average scooter rider is probably 180 to 220 lbs; give or take. Then there's the weight of the scooter itself, which is no less than 75 to 100 lbs. So at peak, we're probably talking 350 lbs?

The riding mower on its own weighs 345 lbs; I looked it up on the spec sheet, then there's probably another 50 lbs for the other batteries and the motor for the deck.

Now I could take off the deck and just make this project about having an autonomous vehicle testing platform. And then in the future change out the motor and transaxle to a more powerful one when I have it. That's a good option I believe


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## sameh4 (Sep 17, 2021)

Electric Land Cruiser said:


> My buddy build an RC mower/plowbot out of a mobility scooter drivetrain. He used a walk-behind mower deck and it was well sized. I don't think a ride-on mower deck would work, too heavy.
> 
> He used an Ardupilot autopilot and FPV stuff and could plow or mow from his big screen TV. He never did get it working autonomously. Sensors and Ardupilot is a lot better now than it was back then 2015-2016.
> 
> Video of plowbot:


@brian_ The RC mower/plowbot in this video shows a trike with rear steering. In your option, what are the disadvantages to this approach.

On the positive side: I can see why you would want the front of the robot to have the most weight to power through the snow.

On the negative side: can't think of much, just intuitively seems wrong, but that could be lack of experience.


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## brian_ (Feb 7, 2017)

sameh4 said:


> The riding mower on its own weights 345 lbs; I looked it up on the specks sheets, then there's probably another 50 lbs for the other batteries and the motor for the deck.


Right, but that includes the engine and transmission.


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## sameh4 (Sep 17, 2021)

brian_ said:


> Right, but that includes the engine and transmission.


Right! I just logged in to say that.


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## sameh4 (Sep 17, 2021)

Thanks for your help everyone! I plan to remove the deck, engine, transmission, and attach the scooter motor.

If I am successful then at the very least I will have a platform for testing autonomous software.

If not I am sure I will learn many lessons hopefully.

I think what I will do is start a new thread to track progress and other other questions there.

Any suggestions on which subforum?

Thanks again!


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## brian_ (Feb 7, 2017)

sameh4 said:


> @brian_ The RC mower/plowbot in this video shows a trike with rear steering. In your option, what are the disadvantages to this approach.
> 
> On the positive side: I can see why you would want the front of the robot to have the most weight to power through the snow.
> 
> On the negative side: can't think of much, just intuitively seems wrong, but that could be lack of experience.


I agree that if the implement is hanging off the front (as a mower deck can be and a plow usually is), then it makes sense to put the drive wheels immediately behind that, and the rear wheels carry little load. Steering the rear instead of the front makes driving the front wheels much easier, and the vehicle can turn very tightly. For a mower it is nice to have the deck out front, to get to the edge of the lawn without having to accommodate the vehicle's front wheels ahead of it. Rear-steer commercial riding mowers are common.

Rear steering is not good for high-speed stability (which may be why it "seems wrong"), but this isn't a road or high-speed vehicle.

If the mower deck is under the middle of the vehicle, it's easier to control with front steering. In the usual layout of a riding mower (not a lawn tractor) such as the John Deere RX73, the engine weight and driver weight are both mostly on the rear, so there's lots of traction and the lightly-loaded front wheels are easy to steer. Unfortunately, in low-traction conditions you get to turn the steering wheel and watch the front tires skid while the thing drives straight ahead, but that's an inherent feature of steering the lightly loaded tires (whichever end they're on). My front-engine front-steer lawn tractor does this in tight turns on grass.


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## Electric Land Cruiser (Dec 30, 2020)

The plowbot does not have rear steering haha.

It uses differential speed between the drive wheels to steer and the rear wheel is just a caster to support the weight and keep it stable. I.e. the stock mobility chair setup.


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## brian_ (Feb 7, 2017)

Electric Land Cruiser said:


> My buddy build an RC mower/plowbot out of a mobility scooter drivetrain.





Electric Land Cruiser said:


> The plowbot does not have rear steering haha.
> 
> It uses differential speed between the drive wheels to steer and the rear wheel is just a caster to support the weight and keep it stable. I.e. the stock mobility chair setup.


Ah, *power chair*, not *mobility scooter *as originally reported; someone not familiar with mobility equipment might not understand the distinction. The drive axle which sameh4 has will be a single motor with differential, so to use the same configuration of vehicle would require the rear wheel to be steered rather than castered.


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## sameh4 (Sep 17, 2021)

brian_ said:


> Ah, *power chair*, not *mobility scooter *as originally reported; someone not familiar with mobility equipment might not understand the distinction. The drive axle which sameh4 has will be a single motor with differential, so to use the same configuration of vehicle would require the rear wheel to be steered rather than castered.


Correct, the mobility scooter is a single motor which is why I assumed it was not a diff drive.


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## sameh4 (Sep 17, 2021)

sameh4 said:


> Thanks for your help everyone! I plan to remove the deck, engine, transmission, and attach the scooter motor.
> 
> If I am successful then at the very least I will have a platform for testing autonomous software.
> 
> ...


I have been searching videos on how to remove the deck and transmission from this mower, and the process does not appear to be terribly difficult, especially with this particular design versus the more recent designs.

Next I need to search about removing the engine!


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## electro wrks (Mar 5, 2012)

This mower has a fairly good Peerless 7 speed manual transaxle. Have you considered just driving this TA through the original belt pulley with a 2-3kW drive motor? Something like this: https://www.amazon.com/BestEquip-Brushless-Electric-Controller-Motorcycle/dp/B0857HSF2P. I have two mowers similar to this model in line for conversions. This is probably what I'll do to drive the rear axles.

Using the mobility scooter axle could be potentially very problematic. You may find your speed too low or too fast, and not many options to correct the problem. Extending axles is way beyond something you can do with JB Weld!

I'll probably power the deck on my conversions with a golf cart motor. I'm planing on using the existing deck belt drive to get the proper blade speed. The GC motor will be mounted directly to the deck with some provision to tighten and loosen the belt. The motor will move up and down, with the deck, in a large hole cut in the frame between my feet (with the motor properly covered, of course!).


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## brian_ (Feb 7, 2017)

electro wrks said:


> This mower has a fairly good Peerless 7 speed manual transaxle. Have you considered just driving this TA through the original belt pulley with a 2-3kW drive motor?


If this is a gear transmission, this makes sense to me. Using an electric motor to drive a hydrostatic transaxle is just a bunch of extra complexity and power loss, and using one of those goofy rubber wheel on disc traction drives is just silly, but an all-gear mower transaxle would be a decently efficient and functional gearbox and differential system.

In a web search, it looks like the RX73 uses a Peerless 910, which is only a single-speed transmission (with forward-neutral-reverse; see pages 41-44 of the service manual)... which is fine for the electric drive if the overall reduction ratio is suitable, and an electric motor could drive through a belt at whatever ratio is desired. It wouldn't make sense for a riding mower with an engine to have a single-speed transmission, so there must be some variable belt drive or similar in addition to the Peerless 910 (if that's what it has); my guess that this has a 7-position selector for the variable speed system, which would not be required with the electric motor.


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## sameh4 (Sep 17, 2021)

electro wrks said:


> This mower has a fairly good Peerless 7 speed manual transaxle. Have you considered just driving this TA through the original belt pulley with a 2-3kW drive motor? Something like this: https://www.amazon.com/BestEquip-Brushless-Electric-Controller-Motorcycle/dp/B0857HSF2P. I have two mowers similar to this model in line for conversions. This is probably what I'll do to drive the rear axles.
> 
> Using the mobility scooter axle could be potentially very problematic. You may find your speed too low or too fast, and not many options to correct the problem. Extending axles is way beyond something you can do with JB Weld!
> 
> I'll probably power the deck on my conversions with a golf cart motor. I'm planing on using the existing deck belt drive to get the proper blade speed. The GC motor will be mounted directly to the deck with some provision to tighten and loosen the belt. The motor will move up and down, with the deck, in a large hole cut in the frame between my feet (with the motor properly covered, of course!).





brian_ said:


> If this is a gear transmission, this makes sense to me. Using an electric motor to drive a hydrostatic transaxle is just a bunch of extra complexity and power loss, and using one of those goofy rubber wheel on disc traction drives is just silly, but an all-gear mower transaxle would be a decently efficient and functional gearbox and differential system.
> 
> In a web search, it looks like the RX73 uses a Peerless 910, which is only a single-speed transmission (with forward-neutral-reverse; see pages 41-44 of the service manual)... which is fine for the electric drive if the overall reduction ratio is suitable, and an electric motor could drive through a belt at whatever ratio is desired. It wouldn't make sense for a riding mower with an engine to have a single-speed transmission, so there must be some variable belt drive or similar in addition to the Peerless 910 (if that's what it has); my guess that this has a 7-position selector for the variable speed system, which would not be required with the electric motor.


That's exactly right. It has a handle on the right side for a multi gear selection, N, R, 1 to 5. I initially thought of just putting an electric motor onto the pulley that drives the transmission and mower deck, especially since the location of this engine; behind the driver seat, is ideal for this. But this wouldn't work with a manual gear shift, right?


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## sameh4 (Sep 17, 2021)

electro wrks said:


> This mower has a fairly good Peerless 7 speed manual transaxle. Have you considered just driving this TA through the original belt pulley with a 2-3kW drive motor? Something like this: https://www.amazon.com/BestEquip-Brushless-Electric-Controller-Motorcycle/dp/B0857HSF2P. I have two mowers similar to this model in line for conversions. This is probably what I'll do to drive the rear axles.
> 
> Using the mobility scooter axle could be potentially very problematic. You may find your speed too low or too fast, and not many options to correct the problem. Extending axles is way beyond something you can do with JB Weld!
> 
> I'll probably power the deck on my conversions with a golf cart motor. I'm planing on using the existing deck belt drive to get the proper blade speed. The GC motor will be mounted directly to the deck with some provision to tighten and loosen the belt. The motor will move up and down, with the deck, in a large hole cut in the frame between my feet (with the motor properly covered, of course!).


I initially thought of just putting an electric motor onto the pulley that drives the transmission and mower deck, especially since the location of this engine; behind the driver seat, is ideal for this. But this wouldn't work with a manual gear shift, right?


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## electro wrks (Mar 5, 2012)

brian_ said:


> If this is a gear transmission, this makes sense to me. Using an electric motor to drive a hydrostatic transaxle is just a bunch of extra complexity and power loss, and using one of those goofy rubber wheel on disc traction drives is just silly, but an all-gear mower transaxle would be a decently efficient and functional gearbox and differential system.


The manual TA does make a lot of sense for a lot of conversions. However, if the electric motor drives both the deck and the TA, in a set up that mimics the original ICE configuration, it would be useful to have the hydrostatic TA to vary the ground speed as the cutting blades runs at a fixed speed. As you point out, it's not as efficient, but there are a lot of hydro units out there just begging for a conversion. Potentially, they could use a separate drive motor. Again, it just would not be as efficient as with a manual TA.

You're right, brian. I looked at the units I have, and mistakenly thought the TAs were the 6 or 7 speed versions. The mowers do have the variable ratio belt drive set up, like many snowmobiles have. It's a real job to replace the belts in this set up and will be glad to get rid of it. This means without all of the gears available, you will have to adjust the final ratio by varying the pulley diameters.


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## sameh4 (Sep 17, 2021)

electro wrks said:


> You're right, brian. I looked at the units I have, and mistakenly thought the TAs were the 6 or 7 speed versions. The mowers do have the variable ratio belt drive set up, like many snowmobiles have. It's a real job to replace the belts in this set up and will be glad to get rid of it. This means without all of the gears available, you will have to adjust the final ratio by varying the pulley diameters.


OK, so we're back to an electric motor with its own transaxle that bolts the wheel onto it ends, right?

About JB Weld, there's a welding shop 10 minutes away that I've used in the past. I plan to take the transaxle from the scooter, along with the ends of the current transmission and seeing what they can do. That's obviously once I start removing things. Right now I am just in the planning stage. I don't want to start the tear down until I have 100% confirmation of what I should do, which it sounds this is still in-flux.

My plan "was"/is to remove the deck, transmission, engine, in that order, and mount the scooter motor with transaxle onto the frame. Then mount the wheels onto transaxle using the hubs that came with the scooter. Of course I'll have to drill holes into the rims of the mower tires, but that should be fine.


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## electro wrks (Mar 5, 2012)

sameh4 said:


> OK, so we're back to an electric motor with its own transaxle that bolts the wheel onto it ends, right?


No. The mower has manual single speed TA, with reverse. If you drive this stock unit with a small motor through 2 pulleys, and a belt, I think it would be better than trying to adapt your scooter axle.

You may have to use different diameter pulleys on the TA and/or the small motor to achieve the desired drive ratio. Not a big deal. You can do it. Again, this is something you can't do with the scooter axle.


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## sameh4 (Sep 17, 2021)

electro wrks said:


> No. The mower has manual single speed TA, with reverse. If you drive this stock unit with a small motor through 2 pulleys, and a belt, I think it would be better than trying to adapt your scooter axle.


OK, makes sense. Just to make sure I understand, with the single speed TA, I can control the over all driving speed by increasing the speed of rotation of the motor, which will increase the rotation speed of the pulley(s), correct? Standard PWM, of course.



electro wrks said:


> You may have to use different diameter pulleys on the TA and/or the small motor to achieve the desired drive ratio. Not a big deal. You can do it. Again, this is something you can't do with the scooter axle.


OK makes sense. I need to go and check where the current pulleys are, but it sounds like a simple swap of current motor with electric motor and a pulley attached to it, should just suffice.


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## electro wrks (Mar 5, 2012)

sameh4 said:


> OK, makes sense. Just to make sure I understand, with the single speed TA, I can control the over all driving speed by increasing the speed of rotation of the motor, which will increase the rotation speed of the pulley(s), correct? Standard PWM, of course.


The motor I referred to is a permanent magnet brushless motor with its own controller for this type of motor. If you prefer a permanent magnet brush type motor with a simple PWM controller, you'll need to find another motor. To be honest with you, the motor I referred to has a short 12mm diameter output shaft. I had to find a source in China for pulleys to fit this shaft. You may have better results with a different motor. Before you get much further, you should settle on a voltage for your batteries, motor(s) and controller(s). What kind of motor were you considering for powering the mower blade?



sameh4 said:


> OK makes sense. I need to go and check where the current pulleys are, but it sounds like a simple swap of current motor with electric motor and a pulley attached to it, should just suffice.


Just to clarify, the only pully you need to keep is the one mounted on top of the transaxle. The rest of the pulleys in the drive system can be removed. You could mount the motor in the position where the ICE was mounted. Unfortunately this takes up valuable battery space. I may try to mount my drive motor under the seat. Maybe where the fuel tank or 12V battery were located. In the past I have fabricated pivots for motors, used door hinges, and used bolts in slots to mount motors. This is because the motor needs to move to tension the belt. You could have a fixed motor and use an idler/tensioner on the belt. It does make the design more complicated. On my mowers, I'll probably use the slot system. This is potentially a no-weld design. But, I may weld parts in place to save time.


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## brian_ (Feb 7, 2017)

electro wrks said:


> The manual TA does make a lot of sense for a lot of conversions. However, if the electric motor drives both the deck and the TA, in a set up that mimics the original ICE configuration, it would be useful to have the hydrostatic TA to vary the ground speed as the cutting blades runs at a fixed speed. As you point out, it's not as efficient, but there are a lot of hydro units out there just begging for a conversion. Potentially, they could use a separate drive motor. Again, it just would not be as efficient as with a manual TA.


I agree. But that means using a hydrostatic drive plus a blade clutch system to avoid the complication of two separate motors (with appropriate controllers) each doing their job optimally - people do it, but it seems like worst-of-all-worlds compromise to me. Yes, there must be hydrostatic drives out there (although no one was offering to give me one when my John Deere crap died), but conversions don't need to be designed to use the things just for the sake of keeping them busy... 

sameh4 wants to build something autonomous. In that situation, controlling the speed of an electric motor is much more desirable than controlling the position of a hydrostatic drive speed control lever.


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## brian_ (Feb 7, 2017)

electro wrks said:


> You could mount the motor in the position where the ICE was mounted. Unfortunately this takes up valuable battery space.


The stock engine location is great battery space, and could be kept free by mounting the motor behind the transaxle, output shaft on top.

In this case, if the unit is to be operated only autonomously (or by remote control) then the seat is not needed and there's lots of room for a battery shelf.


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## MattsAwesomeStuff (Aug 10, 2017)

brian_ said:


> The mobility scooter motor is not to power a blade, it is only to propel the machine.


Oh I misread that. I thought he was using one motor to spin the blade, another to propel the machine.

Yeah, the mobility scooter motors should be fine then for drive-only.


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