Born to be Wired: Page 4 of 6

Under the Hood

In the space once occupied by the air conditioning unit, Richmond installed a 1,500-watt ceramic heater to provide heat for the cab. Securing the piece required Richmond to fabricate a simple mounting plate from sheet metal—an easy-enough task that suited his metal-working skills.

From there, he worked on the power controller and its cooling system—two of the most important components in the electrical system. The pulse-width-modulated (PWM) power controller regulates the power to the vehicle’s drive train by translating the position of the accelerator pedal into power flowing to the electric motor, making the car go.

For every amp that flows to the motor from the controller, 2 watts of waste heat are generated in the controller. At 400 amps, for example, the power controller produces 800 watts of heat. The cooling system circulates water through the controller to cool the electronics, preventing the unit from overheating and causing a thermal shutdown of the Zilla controller.

Outfitting the Cab

With these vital components in place, and after mounting the vacuum pump for the power brakes, the control box, and the remaining battery box above the electric motor, Richmond moved his work from under the hood into the cab. There, he mounted the charger and 45 A DC-DC converter behind the driver’s seat. The extended cab allowed enough room for both components, which should not be exposed to the elements. As an added bonus, the charger produces heat while charging. “When it’s colder outside, I try to charge the truck right before I leave for work. That way I don’t have to run the heater as much, if at all,” Richmond says. 

The DC-DC converter charges a 12-volt battery (also in the cab) that powers the vehicle’s accessories—headlights, windshield wipers, radio, etc. This battery is separate from the traction batteries under the hood and in the bed so that the vehicle can operate standard 12 V accessories independently.

Richmond wrapped up the cab components installation by installing a battery SOC meter—what he considers an “absolute must” for EV newbies who tend to overestimate their battery charge. Much like a gas gauge shows the amount of gas in the tank, the SOC meter shows the amount of energy available in the vehicle’s batteries.

Tying up Loose Ends

One of his final tasks—wiring the AC power cabling to the charger—was perhaps the easiest. The AC plug fit perfectly behind the old gasoline filler cap, saving Richmond from enlarging the existing hole. 

Last but certainly not least was wiring the three-fold safety system and wiring the batteries to each other. The EV’s safety system includes a 500 A fuse in the rear battery box that opens the circuit if the system shorts; a breaker in the control box that is connected to a knob on the dash board for emergency disconnect; and an inertia switch in the control box that causes the circuit to open and stop the motor in the event of an accident. Wiring the batteries seems fairly straightforward—connecting the positive terminal of one battery to the negative of the next—but tight connections are vital to performance and preventing the connections from overheating and melting the terminals.

Turning the Key

Then came the moment he had anticipated for more than a year—the test drive. “It’s a nerve-racking moment. You just hope that everything works and no smoke appears,” he recalls.

Rather than running the motor at the full 400 amps, he took gradual steps. Using his laptop connected to the controller’s computer interface, he programmed the power controller for 50 amps—barely enough power to move the vehicle. He adjusted the settings eight times, adding 50 amps each time until reaching the maximum, 400 amps. At each increment, he checked all the components and connections for signs of heat and unusual noises.