7 3/8 x 9 1/4 T echnical / Build Your Own Electric Vehicle / Leitman / 373-2 / Chapter 10
C h a p t e r 1 0 : E l e c t r i c Ve h i c l e C o nve r s i o n
Low-Voltage System On the low-voltage side, the idea is to blend the existing ignition, lighting, and accessory wiring with the new instrumentation and power wiring. There are six main components on the low-voltage side: • Key switch • Throttle potentiometer • Ammeter, voltmeter, or other instrumentation • Safety interlock(s) • Accessory 12-volt battery or DC-to-DC converter • Safety fuse(s) Every EV conversion should use the already-existing ignition key switch as a starting point. In an EV, the key switch serves as the main on-off switch with the convenience of a key—its starting feature is no longer needed. You should have no problem in locating and wiring to this switch. In Jim’s 1987 Ranger and Paul Little’s Porsche conversions, they mounted the throttle potentiometer (Figure 10-23) on the driver’s side fender well (Figure 10-24, top). Figure 10-24 (bottom) shows it mounted in place and wired up. Instrumentation wiring is simple; just be sure to observe meter polarity markings— the plus (1) marking on the meter goes to the positive terminal on battery. The ammeter is connected across the shunt(s) already wired into the high-current system. The voltmeter goes across the battery. The best solution is to wire the voltmeter so that it is
Figure 10-23 Electric P orsche throttle potentiometer (Cour tesy of CoolGreenCar s.net).
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