DIY Electric Tractor: Page 3 of 4

5. MOUNT THE CONTROLS

We opted for simple, yet safe and serviceable, controls. Don’t put the controls together in a haphazard way, since they are handling large amounts of current. Mount them safely and securely, and tape or put heat-shrink tubing on exposed conductors. You can take care of the cosmetic details like faceplates and labels later.

6. MAKE THE ELECTRICAL CONNECTIONS

Once again, lay out your parts and wiring before making the connections. Keep your basic wiring diagram at hand to avoid mistakes from lapses of attention or simple circuit errors.

It’s helpful if the diagram’s components are roughly in the same relative location as on the tractor. This makes it a lot easier to visually plan and check your configuration, and avoid errors (and plasma events). Again, test connections with a voltmeter if you have any doubts.

We used 4 AWG welding cable with crimped lugs, which are available from most welding suppliers, and insulated the lugs with heat-shrink tubing. Though there’s some debate over the advantages of soldered, crimped, or solder-and-crimp connections, any of the three methods will work well when done correctly. Pre-made cables are available from renewable energy retailers and some auto supply sources.

7. THE FRANKENSTEIN RUN

The “Frankenstein run” refers to the point at which everything is safely wired and ready to run, but a lot of the details are not complete. Besides being a thrill to see your creation take life, it’s also helpful for sorting out problems. It saves a lot of time if you can test before worrying about all the extraneous details. Before flipping the “on” switch, make sure that the vehicle is safe for a short test run—that batteries are secure, connections are insulated, and there are no loose wires or bolts.

8. FINAL CLEANUP & LAYOUT

Once you can see how the tractor’s working, go through each part of the system and double-check everything—mounting hardware, connections, insulation, tie-downs, and the rest. It’s possible to have moved through the main steps, leaving the details for later and then to have forgotten about them. Give all your connections one last check. A loose connection will arc, heat, and ultimately burn once you give it a load.

9. GOING TO WORK

Next, see what your EV tractor can do. We had a quarter-cord of oak sitting on the wrong side of the property, so we charged the batteries, mounted a ball to the trailer hitch, and hooked up the trailer. With the tractor’s transmission in low gear, we pulled the trailer from the low, back section of the property around to the front, up a slight grade, and around to the wood pile with nary a hiccup. Often a motor will heat up under strain like that, but even our “beta” motor was cool to the touch. The batteries had plenty of juice and the test was a resounding success. Later, we took the tractor to the neighbors’—about a quarter-mile away—in fourth gear with nothing in tow, and got back with just enough energy to pull up to the charger.