Charger System

Figure 10-26 Jim Harris’ prototype “magic box” for 1987 F ord Ranger.

Figure 10-27 Paul Little’s EV Porsche “magic box” for components.

Jim’s and Paul’s objectives were to simplify. You’ll see the continuous design evolution of Jim’s magic box in later photographs as the conversion progressed and how Paul Little made it more advanced in his design. Charger System

The benefits of the on-board charger are convenience and the ability to take advantage of on-the-road charging opportunities as they are presented. The dual objectives in

wiring the on-board charging system are to prevent the charging routine from becoming a “shocking” experience (via proper grounding), and to prevent momentary distractions from causing you to drive away while the charging cable is still attached (via a charger safety interlock). There are four main components to the charger system: • Compact on-board charger • Lightweight line booster (optional) • Safety charging interlock • AC input system

In Jim’s 1987 Ranger conversion, he mounted the on-board K & W BC-20 charger on the driver’s side of the aluminum heat sink plate, directly above the motor in the engine compartment, as shown in Figure 10-28 (top). The K & W LB-20 line booster, required by the charger for 120-volt operation, is mounted next to the throttle potentiometer on the driver’s side fender well (Figure 10-28, bottom).

The preferred location for most AC input charging connections in conversion vehicles is usually the location vacated by the gas tank filler neck opening. Figure 10-29 (top) shows that Jim’s choice follows this pattern—it’s behind the original gas cap door. Jim also chose to implement a male “twist-lock” three-prong AC charging connector, enabling him to use a standard extension cable (one end male, other end female) with the male plug on the extension cord end able to mate conveniently with the standard 120-volt AC female service outlets. (Be sure to use a three-conductor extension cable with at least AWG 12 wire in it.) Figure 10-29 (middle) shows an on-board female twistlock three-prong AC connector. Figure 10-29 (bottom) shows that behind the gas tank filler door is not the only location; in this case, a male twist-lock three-prong AC connector has been recessed in the front bumper using a conventional outdoor AC junction wiring box. Figures 11-30 and 31 show examples of how the gas tank filler area can also be used as a great charger location. In this case, they are also using a threeprong connector and a Zivan NG3 charger.

For the charging system, you should use AWG 10 (30-amp rating) stranded insulated copper wire for both the charger-to-battery and the charger-to-AC-input receptacle connections. In order to prevent you (or anyone else) from casually driving away with the extension cord attached while charging, it’s a good idea to implement a charger interlock system. Jim’s approach is to use a relay whose coil is energized by the presence of 120 volts AC, and whose contacts are in series with the 12-volt keyswitch line. When the 120-volt AC line cord is plugged in, this relay latches open and keeps the main battery pack disconnected from the controller and motor—the vehicle is immobilized.

Other EV converters have also used the charger interlock feature to energize battery compartment fans (forced ventilation of the batteries) while charging. Additional interlock possibilities include: sensors that inhibit drive-away when the fault conditions of engine compartment hood open, battery compartment hood open, or AC charging connector access door open are detected; and sensors that inhibit the charging function during fault conditions such as engine or battery compartment hood open (because you don’t want outsiders prying when charging currents and battery gases are present). You might consider any of these options.

In order to prevent you (or anyone else) from getting shocked when touching your EV’s body while it’s charging, the body and frame should be grounded to the AC neutral line (the third prong of the connector with the green wire leading to it). This

neutral wire is connected between the AC input connector and the body or frame, and is utilized only when charging. The batteries should be floating—no terminals touch the frame—and might even be further isolated by locating them inside their own compartment or battery box. This is particularly appropriate for not recommended (but

Figure 10-28 1987 Ford Ranger mounted K & W battery charger (top) and mounted K & W line booster (bottom).

Figure 10-29 AC charging connector options—Jim Har ris’ male (top), optional female (middle), and optional male bumper mount (bottom).

Figure 10-30 Operation Z charging connector and charging plug installed.

Figure 10-31 Operation Z charging connection.