I did it this morning - the last bolt. Up to this point I was thinking that as soon as I fastened the last bolt, I could just turn the key on and see if all the subsystems fired up OK and if they did, I would be ready for a test spin up and down the street. Ha! Silly me.
By the last bolt I mean the connection between the traction battery and the main contactor. But let's backtrack for a minute. Thursday night I added the cell terminal to 2/0 cable connections to the rear battery pack. Last night I put in the remaining umpteen-hundred screws in the traction battery cell terminal posts - that took a while. This morning I cut, crimped, heat shrunk, and installed the 2/0 cable in both the front and rear battery packs. At that point, I was done. Finished.
But wait. I was about to connect the last bolt on the cable between the positive end of the traction battery pack and the main contactor. This would complete the circuit and theoretically, if I put all the fuses into the fuse blocks to turn all the subsystems on, I could just get in and drive. I literally was holding the cable, about to mount it on the bolt, when I paused. I thought to myself, "hang on, this is the main traction pack voltage, if there is anything that I missed somewhere there could be some major flames". So instead I went and got the voltmeter to see if there was any potential between the cable and the bolt. There was, about 180 volts! Then I noticed that the voltage was slowly decaying towards zero, meaning that I was charging up some capacitance somewhere and this was not a dead short. Probably the controller main contactor precharge circuit.
I did want to have the main traction pack connected for at least a minute or two to make sure the EMS computer could see the whole thing. I got a small piece of very thin wire to touch the cable end to the last bolt - if there was any flame danger, this wire would turn bright red and melt harmlessly. As I touched the wire to the bolt, it did spark, but then the wire stayed cool. Good, I got rid of the charge difference. THEN I put the cable onto the last bolt. I went to the front of the car and flipped on the main breaker - this is like Dr. Frankenstein throwing the big switch on the wall to bring the monster to life. For that matter, the big breaker does look like something out of a Frankenstein movie. The EMS display showed the pack voltage properly. I managed to suppress an outburst of "ITS ALIVE!" not wanting to wake up the neighbors. Or my kids. Wait, nothing wakes them up before 11am anyway. Satisfied, I removed the cable from the last bolt.
Later in the day I filled the controller cooling system with antifreeze and saw that there was a big puddle of antifreeze under the car. See? Things do go wrong sometimes! I thought to myself "Gee, I hope there aren't any dogs around" (antifreeze is deadly poison and it smells and tastes like sugar water, so I hear, and dogs will go for it). I turned around and there was the neighbor's dog a couple feet from me, a little black and white boxer, eagerly looking at me. I am not frikken kidding. I took the stupid dog home and came back to continue my work. The drain plug at the bottom of the radiator had a busted O-ring and was the source of the leak. First I thought, "great, now I have to go out on an O-ring hunt" but then I realized that I could probably make one from a sheet of rubber. Do I have rubber sheet? Of course I do, I'm me. Problem solved.
No test drive yet. I need to do this right. I need to check the DC-DC converter operation, to make sure the inrush limiters I added to it don't get too hot. I need to make sure the controller lights up the motor accessory relay board and spits out good status to the iPad. I need to make sure the charger lights up and feeds current into the traction pack. I need to adjust the charger end-of-charge voltage setting. I need to design and build an adapter between the EMS computer and the charger so that the charger shuts off if the traction pack starts to get over-charged. Lithium Ion batteries are quite safe, except if you over-charge them they tend to catch on fire. YouTube it.
Taking a step back and looking at the big picture there are a few deep and profound things I've discovered about doing a project like this - both about the project itself, and about me myself. It's kind of like a Hemingway novel - me versus the metaphorical fish:
1. The final design bears little resemblance to the original design, other than in the crudest block diagram format.
2. For a first-time EV conversion, there is no way that you can have the final design be the same as the original design - to be at the top of the mountain, you have to take every individual step on the way. There are no shortcuts.
3. Because of this, you can't just buy everything you will need in one trip to Lowes or Fry's or Pep Boys or Harbor Freight, despite what your wife says :) You end up making hundreds of trips, like it or not. So much for my green contribution to the Earth by building an electric car...
4. You learn to balance eagerness with contemplation. You need to keep a keen awareness of the consequences of just going for it.
Do these metaphysical concepts have an application in my life adventures on this Earth? Or have I just had too much coffee?
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