7 3/8 x 9 1/4 T echnical / Build Your Own Electric Vehicle / Leitman / 373-2 / Chapter 9
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Build Your Own Elec tric Vehicle
Figure 9-18 AC-style w attmeter goes betw een 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.
