The trike will have a 72 Volt (high voltage) wiring system for powering the rear wheels and a 12 Volt (low voltage) wiring system for the peripherals such as headlight, tail lights, turn signals, horn etc. In some instances these two system overlap which will be shown in the progress photos.
The High Voltage system is powered by six 12 volt deep cycle batteries. The batteries and other high voltage components are wired using 4 awg extra flexible welding cable (all cable and wire sizes are based on recommendations from Kelly Controllers and QS Motors) with 4 awg 3/8″ tubular lug rings. (Photo 1)
A Forney lug crimping tool is used to crimp the lugs to the cable ends. (Photo 2)
A couple completed cables are shown in Photo 3.
I’ve learned from my smaller electric trike builds that my fumble fingered habits can result in some pretty nasty sparks and blown fuses when a tool or other metal object happens to fall into a battery array and Murphy’s Law asserts itself. To help reduce the chances of accidental shorting across battery terminals “Oops Stoppers” (safety covers) are made from cheap and abundant plastic milk jugs. (Photo 4)
The cartons are cut into sections wide enough to cover each battery terminal and its adjoining threaded stud. Two holes are punched out of the plastic so that it fits over the terminal and stud. I used upholstery punches to make the holes nice and round but it could be done with a drill, scissors or exacto knife. The milk carton material can be folded over and pressed by hand to form a “flap” over the top of each lug. (Photo 5)
The safety covers are placed over the terminal and stud and then the battery cable is bolted onto the stud when holds the oops stopper in place. (Photo 6)
The battery array with all of the safety covers in place. (Photo 7) These protectors don’t guarantee the elimination of accidents, but they are a cheap and easy preventative measure.
To further help prevent shorting in the battery pack and to provide a non-conductive mounting surface for the major electrical components, a sheet of acrylic plexiglass is mounted over the batteries. The plexiglass is visible as the slightly cloudy surface between the controllers in Photo 8.
A major safety requirement for any higher voltage electric vehicle is an emergency shut off which is built specifically not to arc and create a major melt down when the battery pack needs to be totally disconnected from the rest of the electrical system. A Holdwell ED250B-1 “Big Red Button” is used for this purpose. The button will be mounted below and just to the right of the rider on the main frame rail and within easy reach. This is also a fairly visible position for emergency crews to find the shut off. A bracket is made from 3/16 flat stock so that the body of the shut off will be surrounded on three sides. (Photos 9 and 10)
The mounting box is welded in place on the frame. (Photo 11) And the big red button is installed. (Photo 12) The positive cable from the battery array runs directly to the emergency shut off and from the emergency shut off to the contactor.
A mounting block for the shunt is made by epoxying together plexiglass sections. This allows the shunt and connectors to be isolated and protected from shorting out on anything metal. (Photo 13)
Connection terminals for the main wiring from each hub wheel to each controller are fabricated from sections of plexiglass epoxied and screwed together. Each wheel and each controller has three phase wires which will be connected on this terminal block. Each controller will also have a plus and a minus high voltage wire which connect at the terminal block to the plus and minus wires from the battery pack. After these photos were taken, screws were added to the terminal blocks to ensure the epoxy joints remained secure. (Photo 14)
Photo 15 shows the connections made on the terminal block.