# Choosing a Motor for a Farm E-Tractor



## ElectricTractor2017 (Feb 28, 2017)

I am in the design phase of converting my 1953 Ferguson tractor from internal combustion 2 Electric Drive. I am planning on using what is cheapest and available to me. I work at a junkyard and I have access to Toyota Prius Transmissions which have the electric motor houses in them. Also I have available to me Toyota Highlander rear electric carriers. 

Does anyone know the feasibility of using one of these two for my tractor conversion? From what I understand the Prius uses 72 volt and I'm not sure about the Highlander. I plan on running the tractor at 48 volts.

Also, would it be possible to use the Prius inverter battery and gas pedal as a complete system?

Since the transmission has two output shafts, one in the front will drive a hydraulic pump and the one in the rear will be the main Drive. Or if the transmission or transfer case will not work for this application comma what is the best forklift motor to mount to a tractor that needs a lot of torque and the RPMs are around 1750.

For my battery, I may just use the individual cells of a Prius battery to get to 48 volts, how is this going to affect the motor RPM and torque.

With so many combinations comma I really just need help on what general direction to go in so I don't waste a bunch of time changing things around in the end. Thanks for all your help everyone


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## madderscience (Jun 28, 2008)

Modern hybrids like the prius run at much higher voltage than 72. I think the prius, as well as the volt and full EVs like the leaf all run somewhere around 300v. Also, most of these motors are so heavily integrated that its hard utilize them without using the entire transmission assembly. The highlander rear carrier might be a better idea though. Weld the diff, lock any clutches, and use it as a motor plus reduction gear. You'd still need to get the inverter working outside the car, or find a suitable replacement. this is a considerable challenge with modern cars, though some people have had success.

I suspect a better fit for your tractor might be to find the electric drive system out of a somewhat more modern (AC driven) forklift. Such a beast will probably run at 48 or 72V already. However, I'm guessing the continuous HP requirement for a tractor is more than for a fork lift so you'd have to take that into account. Of course, a DC forklift would work too, but you'd have to work a little harder to keep dirt out of the motor and cooling might be more of an issue. ~1800rpm rated speed is common for 3 phase electric motors and I'm guessing forklifts also generally use lower speed motors. 

The best thing to deal with the hydraulic pump would be just use a separate motor. Again, that forklift probably already has a complete electrically powered pump unit waiting to be repurposed.

Good luck


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## ElectricTractor2017 (Feb 28, 2017)

madderscience said:


> Modern hybrids like the prius run at much higher voltage than 72. I think the prius, as well as the volt and full EVs like the leaf all run somewhere around 300v. Also, most of these motors are so heavily integrated that its hard utilize them without using the entire transmission assembly. The highlander rear carrier might be a better idea though. Weld the diff, lock any clutches, and use it as a motor plus reduction gear. You'd still need to get the inverter working outside the car, or find a suitable replacement. this is a considerable challenge with modern cars, though some people have had success.
> 
> I suspect a better fit for your tractor might be to find the electric drive system out of a somewhat more modern (AC driven) forklift. Such a beast will probably run at 48 or 72V already. However, I'm guessing the continuous HP requirement for a tractor is more than for a fork lift so you'd have to take that into account. Of course, a DC forklift would work too, but you'd have to work a little harder to keep dirt out of the motor and cooling might be more of an issue. ~1800rpm rated speed is common for 3 phase electric motors and I'm guessing forklifts also generally use lower speed motors.
> 
> ...


Thank you so much for your reply, that's what I was figuring is that it is going to be very hard to figure out all the electronics needed to get it to run right and then the high-voltage is not going to lend itself that great too a high-torque application.

What do you think about this forklift a motor that I found on my local Craigslist?

https://stlouis.craigslist.org/pts/5995627035.html

Same as: http://www.hydroponicsonline.com/st...tor-97F20-30040-165-KW---EV_200646899391.html


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## Karter2 (Nov 17, 2011)

What do you intend/expect this tractor to be used for ?
Do you want to reproduce the performance/power of the original engine ?
...or will this just be a fun/show ride and maybe a yard mower ?
..or do you intend to drag tree trunks up muddy hillsides ?
If you search this forum, you will find conversions on similar tractors (Ford 8n?), some using quite small 8kW Agni type motors...
http://www.diyelectriccar.com/forums/showthread.php/e-ford-8n-80143.html
https://www.flickr.com/photos/mbarkley/sets/72157622014927239
...but it all depends on your intended use.
Its always best to clarify your requirements and budget limitations.
Remember, if you use a powerful motor, you would need a powerful (expensive ?) battery pack and controler to make use of it.


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## madderscience (Jun 28, 2008)

regarding the link to the GE forklift motor, just going by weight and KW rating it probably isn't too far off from what you might need. As the prior post suggests, the best exercise for you to do might be to figure out the HP requirement for your tractor. If you already use it then you can work backward for example from fuel consumption. if its a gas engine, 1 gallon of gas is 33.6kwh of energy. that 50's engine might only be 20% efficient, so really you get 7kwh of energy per gallon out of it. So if you burn 2 gallons per hour, you are using 15kw, and that GE motor might be a pretty good match. If you are using 10 gallons per hour, then you really need to rethink. If you use less gas per hour, then you could get away with smaller.


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## ElectricTractor2017 (Feb 28, 2017)

Karter2 said:


> What do you intend/expect this tractor to be used for ?
> Do you want to reproduce the performance/power of the original engine ?
> ...or will this just be a fun/show ride and maybe a yard mower ?
> ..or do you intend to drag tree trunks up muddy hillsides ?
> ...


My goal is to reproduce the power of the internal combustion engine or exceed it slightly. This tractor will have a front loader that will have its own small motor running a hydraulic pump. I also want to tractor to be able to run for at least four hours of continuous work. I believe two Banks of four Everstart 29dc batteries will give me enough amp hours, but if not I will just add another bank of four because weight is not an issue.

Thanks for your reply!


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## ElectricTractor2017 (Feb 28, 2017)

madderscience said:


> regarding the link to the GE forklift motor, just going by weight and KW rating it probably isn't too far off from what you might need. As the prior post suggests, the best exercise for you to do might be to figure out the HP requirement for your tractor. If you already use it then you can work backward for example from fuel consumption. if its a gas engine, 1 gallon of gas is 33.6kwh of energy. that 50's engine might only be 20% efficient, so really you get 7kwh of energy per gallon out of it. So if you burn 2 gallons per hour, you are using 15kw, and that GE motor might be a pretty good match. If you are using 10 gallons per hour, then you really need to rethink. If you use less gas per hour, then you could get away with smaller.


Well I already acquired this forklift motor, so we will see how it works and if it doesn't perform good enough then I will just get a more powerful one and figure it out from there.

Do either of you guys know if I can get away with not using a motor controller? Isn't there some way to just use a potentiometer?


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## Karter2 (Nov 17, 2011)

ElectricTractor2017 said:


> My goal is to reproduce the power of the internal combustion engine or exceed it slightly. This tractor will have a front loader that will have its own small motor running a hydraulic pump. I also want to tractor to be able to run for at least four hours of continuous work. I believe two Banks of four Everstart 29dc batteries will give me enough amp hours, but if not I will just add another bank of four because weight is not an issue.
> ....!


FYI...you may want to re think your battery requirements !...
Even at just a 50% duty cycle usage on that motor (say 10kW load) and at 48v, you will be drawing 200amps average.
That would mean your dc29 battery pack is drained in about 45mins ! (Maybe less)
(You will never get the rated 115Ah from lead cells at that discharge rate.)
So for 4 hours run time, you will likely need 5 times the proposed pack size...(1000+ Ah)...!!! Is that 40 of those dc29s ?
.. That would be a lot of $$$$s and weight !
...and then there is the little matter of charging ?

It would be unrealistic to try running without a controller.
You would simply waste half your battery capacity.
Look for a fork lift controller to suit the motor.


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## dain254 (Oct 8, 2015)

Doing the absolute cheapest thing a person could use a contactor in place of the controller so long as your still using the clutch from the engine. Losing the ability to throttle the engine on a garden tractor isn't an issue but on my 59' Massey 65 I wouldn't want to lose throttle control... makes running implements and general operation more enjoyable. 

To do the absolute cheapest thing I feel you will spend a lot of effort to create something that is largely impractical since it will only run for ~20min on the components you've listed. A complete chevy volt battery could be obtained through your junk yard for $1200 or so... a person could break it down into a 12S7P pack that would be 48V and be 14kwh or so. Line the modules up where the gas tank was and wire them all in parallel! You may get a couple hours depending on duty cycle.


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