Wiring It All Together

Figure 9-18 AC-style wattmeter goes between AC outlet and charger.

the wattmeter’s reading, charge your EV’s battery pack, do your tooling around, then come back and repeat the process. Over time, the wattmeter tells you your EV’s energy use patterns, and can quickly tell you if something is amiss (dragging brake shoe, etc.) by deviations from the pattern. Plus you can use the results to show your wife/husband, friends, neighbors, and community just how much money you saved compared to an internal combustion engine vehicle.

Wiring It All Together

Five things are important here—wire and connector gauge, connections, routing, grounding, and checking. We’ll cover them in sequence.

Wire and Connectors

This might be one of the last things you think about, but it’s by no means the least important. While your wire size and connector type choices on the instrumentation side are not as important as the connections you make with them, all of these are important on the power side.

Working with AWG 2/0 cable gauge wire is not my favorite pastime—think of it as involuntary aerobic exercise—but its minimal resistance guarantees you a highefficiency EV as opposed to the world’s greatest moving toaster.

Minimal resistance means how the connectors are attached to the wire cable ends is equally important to the overall result. Crimp the connectors onto the cable ends using the proper crimping tool (ask your local electrical supply house or cable provider) or have someone do it for you. A dinky triangle contact crimp, which you can easily get away with when working in AWG 18 hookup wire, is fatal to your round ferrule AWG 2/0 connector. It will cause you a hot spot that sooner or later will melt (or be arcwelded) by the routine 200-amp EV currents. Meanwhile, you will get poor performance. If you are getting 20 miles per charge and your neighbor is getting 60 miles per charge with the identical setup, and you checked for the obvious mechanical-motor-controllerbattery reasons, chances are it’s in your wiring. Treat each crimp with loving attention and craftsmanship, as if each was your last earthly act, and you will be in heaven when it comes to your EV’s performance.

Connections

On the power side, connections are important. These occur when your AWG 2/0 wire connectors attach to motor, controller, batteries, shunts, fuses, circuit breakers, switches, etc. Check to ensure surfaces are flat, clean, and smooth before attaching. Use two wrenches to avoid bending flat-tabbed controller and fuse lugs. Torque everything down tight, but not gorilla-tight. Check everything and re-tighten battery connections at least monthly.

Routing

Aim for minimum length routing on the power side. Leave a little slack for installation and removal, and a little more slack for heat expansion; then go for the line that’s the shortest distance between the two points. On the instrumentation side, it’s neatness and traceability that count: you want it neat to show off to friends and neighbors, you want it orderly so that you (or someone else) can figure out what you did.

Figure 9-19 shows the ideal layout of Don Moriarty’s custom sports racers— everything neatly laid out on a giant heat sink backing plate (1/8-inch to 1/4-inch aluminum reinforced and cross-braced, etc.). This shelf can be hinged at the back to the firewall and pinned in the front (or vice versa). Gas shocks (of the rear trunk deck variety) can be added to make its 30 to 50 lbs. easy to lift up for access—a user-friendly touch. In Chapter 10, Jim Harris’ “magic box” gives you another page for your idea book—a different approach that produces the same desirable results: minimum length combined with neatness and traceability.

Grounding

The secret of EV success is to be well grounded in all its aspects. “Well grounded” in electrical terms means three things:

Figure 9-19 Dan Moriarty’s nearly ideal layout of electric vehicle control and wiring of components.