DIY Electric Tractor: Page 2 of 4

STEP BY STEP

1. REMOVE THE GASOLINE ENGINE

Remove all gasoline-related parts—the motor, control cables, wiring, and fuel tank. Keep what you can in serviceable condition—you may be able to sell the parts. Save the drive mechanism—whatever is attached to the output shaft of the motor (including the pulley).

2. CLEAN THE TRACTOR

Your EV will operate without making a greasy mess, so take the opportunity to clean everything now. It’s up to you if you want to spend time repainting or finishing the old tractor, but getting it clean makes working on it more pleasant.

3. LAY OUT THE PARTS

Check out the space that’s available and try laying out your parts in the chassis. The belt drive requires mounting the motor in the same spot as the gas engine. Finding the best placement for your batteries and controls can take some experimentation.

4. MOUNT THE MOTOR & BATTERIES

Mounting the motor requires drilling a 1/4-inch-thick aluminum plate with a center hole for the output shaft, four holes for the motor, and four holes that line up with the existing holes in the chassis. This doesn’t have to be precise or pretty—you can use scrap plate if you have it. Use bolts with washers and lock washers to secure the motor.

A new V-belt drive pulley, similar to the original, will be used. Be sure to match it to the shaft diameter of the electric motor. Since we’re running a motor that will develop roughly the same rpm as the gas engine, using the same diameter pulley will keep speeds about the same as original.

The four sealed lead-acid batteries fit inside a plastic battery tray that was purchased at an auto parts store, and it happened to slide right into a space at the front of the chassis. If you’re not so lucky, it may take some effort to figure out the battery placement, especially if the batteries are larger or more numerous. Regardless of where they are placed:

• Mount the batteries securely. It’s vital that they do not shift and tip, especially if they’re flooded batteries. Many DIYers will build robust battery boxes or racks made from angle iron or aluminum sheet. 
• Isolate the battery compartment, if possible. Plastic battery boxes are ideal, both as electrical insulators and to contain electrolyte spills.
• When making electrical connections or just placing the batteries in the chassis, keep in mind that you’re dealing with potentially lethal current. Use insulated tools (or insulate yours by wrapping them with electrical tape), and double-check every effort. If you have any doubts about making a connection, check it with a voltmeter first to verify that you’re about to do what you think you’re about to do. We call unintentional arcing “plasma events,” and they’re dangerous.