Yup, I was itching to use this new laser cutting service called SendCutSend, so I drew up a lightning bolt in Adobe Illustrator and sent it over. A week later I had the piece, I cut it to the shape, and welded it in. Looks awesome!
Onto the wiring! Finally! No more putting it off
First thing I did was add the necessary pre-charge resistor and protection diode to the main contactor (it's like a super huge relay for switching the power on/off between battery and motor controller, and it works exactly like the starter solenoid under you car's hood). The precharge resistor goes between the main lugs and is required by the motor controller, and the protection diode goes between the coil lugs and it prevents a voltage spike when the contactor is turned off and the magnetic field is collapsed.
Before I could any further, I needed a wiring diagram. Duh! I was going to work off of this one from another builder with very similar parts as mine:
https://endless-sphere.com/forums/viewtopic.php?f=10&t=109761&p=1610494#p1610612
But when I was looking closer, I saw that the full 72v was applied to the contactor's smaller lugs, and not 12v as I was expected. And that got me thinking...
It turns out that the 72v contactor that I bought from Kelly (KZJ400A) doesn't mean that the main lugs are rated for 72v - it means that the coil is rated for 72v. I confirmed this myself by trying to open it with a 12v lead acid battery (didn't open) and then my 72 battery pack (opened with a nice kick!).
Only problem with that is that I really don't want to run 72v through my kill switch and my ignition (key) switch. I've seen from a few people that they were able to run the 72 volts (it's only drawing an amp or less) through the OEM switch without problems. But my ignition switch was actually made for a 6v circuit! And then there's the kill switch, which has an interal LED that would go up in smoke if given 72 volts.
So I ordered a different contactor. I got this
TE LEV200 but off Ebay for only $70 including shipping, and is shipped from within my country and not from overseas. I thought that was a fair price, EVwest has similar style contactors selling for $169. It arrived in the mail today.
Here's my wiring diagram for the 12v contactor:
While I was waiting for the new part to get in the mail, I started wiring the throttle. There's 6 wiring coming out of the throttle, three for the throttle itself and three for the switch that I'm planning on using for the turn signals. And holy hell are the wires tiny!
Working with wires this small really sucks. The wires that I bought to build the wiring harness are 16 gauge, and these tiny wires must be like 24 gauge. So making a connection between the two sizes is tricky.
The first connector I tried was a crimp on connector with a heat-shrink layer around it. I think I got it connected fairly well, but I really needed to squeeze hard on the side with the smaller wire. And then when I used a heat gun to shrink the heat-shrink, it exposed cuts that I accidentally made with the pliers.
And you REALLY don't want these wires to short out, because if they do then the motor controller will see the full 5v which is WIDE OPEN THROTTLE! (This is also why the kill switch is important).
So I cut off those connectors and tried another one: a heat shrink tube with a low-temp solder ring. This worked really well.
My next challenge is to get the other end of the wire into the connector that plugs into the motor controller. They gave me all the little parts so assemble it myself. Going to be fun.
So that is as far as I got. Not very far!