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Harley Golf Cart - Gas to Electric


Justin Smith's Avatar
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06-09-15, 07:58 PM   #1  
Harley Golf Cart - Gas to Electric

Hey all! Sorry it's been awhile. Anyway I just got an old Harley Davidson golf cart that has a bed on it big enough for my needs and the frame is in great shape, however the engine is shot. What I'd like to do is put in an AC motor. I think I have everything figured out except reverse, and if the motor is right. Originally the engine ran in reverse for reverse, as for now I need to find a way to reverse the motor. I think 5HP would be enough considering most electric golf carts I've seen have only a 3 - 4 HP motor and are carrying around 6 batteries. It's belt-driven so I think I can gear it down lower for more torque as well, I don't really need to go fast. Anyway I found a motor on Ebay that I think will work, here's a link to it. It says it's reversible. 5 HP Compressor Motor Electric 56 Replacement for Leeson 111275 Single Phase | eBay

And here's what the unit looks like:

 
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06-09-15, 09:35 PM   #2  
How to you intend to run an AC motor on batteries? Please don't tell me you want to put a generator in the bed?


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06-09-15, 10:29 PM   #3  
How to you intend to run an AC motor on batteries? Please don't tell me you want to put a generator in the bed?

I want to put an AC generator under the seat area. AC generator runs the drive motor, lights, convenience outlet, and radio. When the pedal is depressed I want it to close a contactor and start the AC motor.

 
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06-09-15, 10:41 PM   #4  
Well, I'll leave it to the Pros, but let me point out a few things. The motor is 208-240 and 5HP. As I understand it, that will probably take a pretty healthy generator. A couple of quick searches show it would draw about 28A at 240V. That's about 7000W? Might be hard to fit that under the seat? And I imagine that's not even the starting draw.

I know you like experimenting with this kinda stuff, but I think it would be a heck of a lot easier to replace the original DC motor and batteries and use a small genny for extended range if that's your desire. Or find a gas cart somewhere.


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06-10-15, 12:58 AM   #5  
Justin, you really need to think a lot more about this. If you use a gasoline engine to drive a generator then use the generator to drive the motor you would be far better off to just drop the generator and motor and use the engine to drive the cart directly. Doing it the way that you propose you would have very poor speed control, needing to throttle down the engine to slow the generator to lower the frequency to the motor and THAT, my friend, is very hard on the motor.

The other way would be to use a constant speed generator and then a frequency changing drive to run the motor and that gets expensive.

I would suggest that you look at the transaxle assembly and see if it is the same, perhaps with an input shaft adapter, that is used on the electric carts. If it is then going to a Cushman electric motor would probably be the easiest and best retrofit. Using either a drum switch or solid state relays for reversing would be easy and if you wanted to add a generator set you could have a DC generator as well to recharge the batteries. This would allow you to use a fairly small battery bank.

 
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06-10-15, 04:46 AM   #6  
I'm trying to figure out why developing a hybrid drive system is supposed to be easier or better than simply fixing the motor. Even switching it to a more normal DC electric system I would call crazy unless you want a big project for mediocre results at best. If anything that would not be a good donor cart for an AC drive like you mention because it does not have a transmission with forward and reverse. I noticed you also never mentioned anything about speed control and how you would accomplish that.

If you want the cart to work you are best off simply repairing it the way it was built. You don't even have to do the engine work yourself. It's small enough to be put in a box and UPSed to a shop for re-build or exchange. It's commonly done with golf cart engines.

 
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06-10-15, 04:51 AM   #7  
Just my opinion but I would go to tractor supply and get a new gas engine and retro fit it. Use a simple centrifugal clutch or pulley and belt system to drive the cart.

It would be far cheaper and easier.

17 hp briggs? Or the 7 hp kohler may be good enough.

Tractor Supply Co. - Enjoy searching:enines

But whats wrong with the engine it has now?

The issue with that old engine is parts are expensive somewhat. You can get rebuild kits anywhere.


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06-10-15, 06:20 AM   #8  
For an easy swap that won't work. The old Harley carts had a two stroke engine and to drive in reverse you actually run the engine backwards. The transmission doesn't have a reverse gear so even with a new engine and centrifugal clutch the cart won't have reverse.

 
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06-10-15, 06:42 AM   #9  
The transmission doesn't have a reverse gear so even with a new engine and centrifugal clutch the cart won't have reverse.
I would not worry about reverse. But thats me. I would not spend the money on that.




I would get a horse probably and do this. Youll have a nice friend thats cheap to feed...



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Justin Smith's Avatar
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06-10-15, 08:21 AM   #10  
Justin, you really need to think a lot more about this. If you use a gasoline engine to drive a generator then use the generator to drive the motor you would be far better off to just drop the generator and motor and use the engine to drive the cart directly. Doing it the way that you propose you would have very poor speed control, needing to throttle down the engine to slow the generator to lower the frequency to the motor and THAT, my friend, is very hard on the motor.

The other way would be to use a constant speed generator and then a frequency changing drive to run the motor and that gets expensive.

I would suggest that you look at the transaxle assembly and see if it is the same, perhaps with an input shaft adapter, that is used on the electric carts. If it is then going to a Cushman electric motor would probably be the easiest and best retrofit. Using either a drum switch or solid state relays for reversing would be easy and if you wanted to add a generator set you could have a DC generator as well to recharge the batteries. This would allow you to use a fairly small battery bank.
I forgot completely about speed control. I think that's the killer of doing this with an AC motor. And those DC motors look extremely expensive.


I'm trying to figure out why developing a hybrid drive system is supposed to be easier or better than simply fixing the motor. Even switching it to a more normal DC electric system I would call crazy unless you want a big project for mediocre results at best. If anything that would not be a good donor cart for an AC drive like you mention because it does not have a transmission with forward and reverse. I noticed you also never mentioned anything about speed control and how you would accomplish that.

If you want the cart to work you are best off simply repairing it the way it was built. You don't even have to do the engine work yourself. It's small enough to be put in a box and UPSed to a shop for re-build or exchange. It's commonly done with golf cart engines.
I wanted to do a hybrid drive mainly for the cool (to me) factor. Plus I understand electric motors a lot more than I do engines. I have a friend who rebuilt the engine in this once, and tried to rebuild it again and told the owner it was shot. He told me the guy didn't add oil to the gas last time he filled it up, as well as the crankshaft being bent among other things. I'm gonna be better off getting a new engine for it or converting it to electric.

I think I'm just gonna get a used gas engine off Craigslist and convert it to LP. Do you think I could use the old starter from the Harley motor for reverse? Would this engine work?

Briggs and Stratton engine

 
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06-10-15, 11:21 AM   #11  
I still think easiest is having the original engine fixed or finding an exchange/overhaulded engine... but where's the fun in that?

What metal fabrication tools do you have? I can tell you from experience that re-engining with even a very similar engine involves a lot of little headaches. Part of the frame is in the way... got to make a motor mount... need a bracket to hold this or that... gotta make an exhaust system.

First, very carefully take measurements of the space available for the new engine. The old 2 strokes were tiny. Most more modern carts have custom engines where the cylinder is really laid over to cut the engine's height. Retrofitting a standard 4 stroke usually involves lifting the cart to create enough space below the seat.

Keep in mind that the primary and secondary clutches moving plates are on opposite sides so engine offset and alignment is not immediately apparent. You'll want to take that into account because the engine may be shifted over an inch or two from where you thought it should go... and it usually ends up in the way of something.

Next you'll want to know the engine's crank rotation direction. You'll probably want one that turns CCW when facing the end of the shaft. Before buying an engine you'll want to look at primary clutches and what the bore is so you can find an engine with a shaft to match. If they don't match you'll be in for some machining and some very fussy machining if one of them has a tapered shaft or bore.

Fuel is easy. Exhaust is annoying but not rocket science if you have to tools.

Do you want the cart to operate like a golf cart where it starts automatically when you step on the gas pedal? If so that will require an engine with electric start. If you don't mind pull starting and letting it idle until you step on the gas you can go with a manual start engine. Which way you go might make a difference in the primary clutch you choose and what drive belt you'll need. Having the engine idle without the cart moving will require the primary clutch to fully disengage at idle and a long enough belt so it doesn't drag. It's not a concern if you go with traditional step on the gas to start as the carts moving whenever the engine is running.

For reverse I'd say forget it or throw together a totally separate reverse system. Maybe use a starter motor with a solenoid to engage a ring gear to drive the cart in reverse for short distances. You might be able to modify the existing carts starter motor with a sprag clutch.

 
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06-10-15, 04:57 PM   #12  
Sorry for mentioning Cushman when it is a H-D cart...

It's belt-driven...
That will make it easier. How much do you want to spend on a motor? You can get rebuilt motors for GE Elec-Trak garden tractors for about $200 to $300 dollars depending on the horsepower. Add in the original Elec-Trak speed control for maybe another $100 or so and you would be set. Or, you could use three, 12 volt batteries connected in series for the top speed and then with contactors tap off the batteries for a slow and medium speed. Using three independent battery chargers (regular 12 volt chargers) would go a long way to minimizing unequal charge across the entire battery bank.

If you still want the hybrid drive then you could use an Elec-Trak mower motor (about $150) as a generator, driving it off of a small engine of about 2-3 horsepower.

 
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06-10-15, 08:35 PM   #13  
Thanks for all your replies, guys! It's given me a lot to think about and some great ideas!

I still think easiest is having the original engine fixed or finding an exchange/overhaulded engine... but where's the fun in that?
I want the fun way, not the easy way!

What metal fabrication tools do you have? I can tell you from experience that re-engining with even a very similar engine involves a lot of little headaches. Part of the frame is in the way... got to make a motor mount... need a bracket to hold this or that... gotta make an exhaust system.
I have access to a shop with more tools than I know how to use at my disposal.


Do you want the cart to operate like a golf cart where it starts automatically when you step on the gas pedal? If so that will require an engine with electric start. If you don't mind pull starting and letting it idle until you step on the gas you can go with a manual start engine. Which way you go might make a difference in the primary clutch you choose and what drive belt you'll need. Having the engine idle without the cart moving will require the primary clutch to fully disengage at idle and a long enough belt so it doesn't drag. It's not a concern if you go with traditional step on the gas to start as the carts moving whenever the engine is running.
I want to have a keyed start. I hate the traditional golf cart engine setup.

For reverse I'd say forget it or throw together a totally separate reverse system. Maybe use a starter motor with a solenoid to engage a ring gear to drive the cart in reverse for short distances. You might be able to modify the existing carts starter motor with a sprag clutch.
That's what I'm thinking. The most I'd need reverse for is to back out of a garage.

That will make it easier. How much do you want to spend on a motor? You can get rebuilt motors for GE Elec-Trak garden tractors for about $200 to $300 dollars depending on the horsepower. Add in the original Elec-Trak speed control for maybe another $100 or so and you would be set. Or, you could use three, 12 volt batteries connected in series for the top speed and then with contactors tap off the batteries for a slow and medium speed. Using three independent battery chargers (regular 12 volt chargers) would go a long way to minimizing unequal charge across the entire battery bank.

If you still want the hybrid drive then you could use an Elec-Trak mower motor (about $150) as a generator, driving it off of a small engine of about 2-3 horsepower.
I wanted to do this "on the cheap" as they say. I think I'll scrap the hybrid drive for this project. Maybe if I get an electric cart with bad batteries I'll try it some time down the road.

 
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