DIY Electric Tractor: Page 4 of 4

Intermediate

Inside this Article

The newly converted tractor
The newly converted tractor earns its keep by hauling a load of firewood.
The original donor tractor.
The original donor tractor.
Power switch
Power switch
SOC meter
SOC meter
2-amp charger
2-amp charger
Main contactor
Main contactor
Before the engine removal and cleanup.
Before the engine removal and cleanup.
After the engine removal and cleanup
After the engine removal and cleanup. Note the new holes drilled for the motor adapter plate.
Test the possible configurations
Before installing the final motor and batteries, test the possible configurations to see which ones work best for your tractor.
The motor and batteries are placed and preliminary connections made.
The motor and batteries are placed and preliminary connections made.
The new controls
The voltmeter, power switch, and charger input receptacle—all conveniently mounted on the dashboard.
The fuse and contactor are mounted behind the dashboard
The fuse and contactor are mounted behind the dashboard on a cross-brace.
The converted tractor
The converted tractor with the upgraded motor and mower deck, operated by the author’s son, Tyler Dillard.
The new Motenergy ME1004 with the stacked pulley in place.
The new Motenergy ME1004 with the stacked pulley in place.
The updated tractor, with the Motenergy motor and mower deck
The updated tractor, with the Motenergy motor and mower deck, awaiting its new batteries.
The newly converted tractor
The original donor tractor.
Power switch
SOC meter
2-amp charger
Main contactor
Before the engine removal and cleanup.
After the engine removal and cleanup
Test the possible configurations
The motor and batteries are placed and preliminary connections made.
The new controls
The fuse and contactor are mounted behind the dashboard
The converted tractor
The new Motenergy ME1004 with the stacked pulley in place.
The updated tractor, with the Motenergy motor and mower deck

The Continuing Project

From the testing, it was clear the tractor will be a productive tool around the grounds. We decided an investment in the purpose-built Motenergy would be worthwhile. The 48 V, permanent-magnet DC motor with a 1-inch shaft will have enough power for the stacked pulley that also drives the mower deck. However, the bigger motor will work well within its load range and will heat up less, and will be more efficient.

Switching the two motors was a matter of unbolting the first one and using the same mounting plate for the new motor. Both motors have a standard NEMA C bolt pattern, so the holes matched up perfectly—and the cable attachment was also a match. Then all we needed to do was remount the mower deck.

This is a great example of building a balanced system. When the tractor had the small motor, small batteries, and a relatively light load, it provided good power and range. Once we increased the motor size, we could add more load, like the mower deck. However, the batteries were not up to the task. Monitoring how much “mowing range” the original batteries provided gave us an understanding for how we’d need to upgrade. The smaller batteries let us mow just barely a quarter-acre, if they had a full charge and we were careful not to waste energy.  Increasing the battery capacity to four quality small, flooded lead-acid automotive batteries in the 40 to 60 Ah range was necessary to get an acceptable mowing range of our quarter-acre lawn, with a little extra for insurance. A nearby salvage yard sells used batteries for $35 each. Even better would be to use 12 V deep-cycle batteries, similar to those intended for golf carts.

What will come after that? Adding function is simply a matter of adding another motor, so there are many options: a power take-off, hydraulics, etc. For now, though, it looks like the resident teenager has a lawn to mow!

Access

Ted Dillard has been an avid gardener since childhood and is an evangelist for all things electric. He writes The Electric Chronicles (devoted to two-wheeled electric vehicles), and is the author of ...from Fossils to Flux, a basic guide to building an electric motorcycle. When he’s not in his garden or in his shop working on his next electric project, he can be found at evmc2.com.

Suppliers (Parts & Kits):

Electric Motorsport • electricmotorsport.com

EV Drives • evdrives.com

Motenergy • motenergy.com • Permanent magnet motor

Thunderstruck Motors • thunderstruck-ev.com

Comments (4)

Little Eddie's picture

Converting to battery power is a great idea for a garden tractor I converted one 15yrs ago and it is still cutting grass on a daily basis, I have had to renew the batteries every 7 yrs I am just on my 3rd set now, my design will cut up to 2 acres on a 50cent charge there are no belts or pulleys and no oil on the entire tractor, it can pull a trailer for about 8hrs on a charge, because battery run time is the most important aspect of most conversions I paid particular attention to the most efficient design I could up with, I used 3 separate small motors one for the drive with electronic speed control and two smaller with a cutter blade mounted on the shaft for each cutter, this design only uses the battery power req to do the job, very little wasted battery power, it uses magnetic breaking of both tractor and cutter blades and automatically applies parking brake when you stop or get off the seat.
Little Eddie Edmond Electric

SRland's picture

I love this project.

Rayzer's picture

This is pretty cool! I do have a few questions though;

1) How well do these electric motors stand up to all the dust from mowing, are they sealed?

2) What would it take to extend the mowing time to an acre, more or bigger batteries?

3) Would a bigger HP motor help with heat build up?

4) What would be the pros and cons of using a brushless motor instead of a brushed motor?

5) Have any cost comparison been done to see the difference between buying gas and the electricity used to charge this?

As you can probably see from my questions, I am completely ignorant on this subject. Great article, thanks I enjoyed it!

Little Eddie's picture

I can answer some of your questions,
1, I use sealed permanent magnet brush type motors, these stand up very well because they are sealed also reasonable price
2, This is the biggest challenge with any battery powered equip, Use the most efficient design you can afford, I can get 2 acres cutting or 8hrs pulling trailer per 50cent charge, 4 x 12v 120ah batteries in series 48v system
3, No! the smallest motor that can do the job is the most efficient, electric motors can be overloaded at least 3 times there rated HP for short times without damage, e,g pulling up hill etc, with an efficient design it takes very little power to move a lawn tractor across level grass,
4, Brushless motors are slightly more efficient than Permanent magnet motors but they require an electronic controller to run each one, the extra cost is not really worth gain in efficiency unless you can get a deal?
5, Yes my edmond tractor uses about 1/20 of the energy that a comparable gas tractor uses,so even if the electricity is generated by coal I use much less of it and much less pollution, depending on allot of factors I believe it takes anywhere from 4 to 8 ltrs of gas per acre with a gas tractor or only about 25cents 2KWH of electric per acre with my electric tractor.
Little Eddie Edmond Electric

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