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Sunday, June 12, 2011

Weekly update

The motor controller mounts have been installed. I made them from 1/16" polycarbonate strips: measured the height the controller needs to sit, heated up the plastic with a heat gun until it was soft, then used some square blocks to form it into a little bracket. The fore and aft mounting brackets have a little hole drilled in them that allows a 4-40 screw to go through and into a mounting hole in the MC. Small pieces of super vibration dampening rubber will be placed between the mounting brackets and the MCs.


The little white wires running from one end of the board to the other in the picture below are wires from a magnetic deadman's switch that controls the contactor coil. A magnet on my foot closes the switch, thus activating the contactor...so when I fall off (not if), the contactor will open, and the board won't keep going.


Below are pics of the partially assembled board.

It's starting to look like a longboard.
Hell yeah. Note: BWD is in the background
I tried standing on it and turning, but discovered that there's not enough ground clearance (I get edge bite). Luckily, I bought a ton of riser pads and installed all of them...it looks kinda funny, but that got the ground clearance up to a more reasonable 1 3/8 inches. It'll also give me more suspension, which is much needed with such a stiff deck.



While all of this was going on, I was balancing/charging my giant lipos. It turns out that one of the cells in one of the packs was much lower than the others. At first I thought it might be a bad cell, but the charger has been able to get it up from 3.4v to 3.94 at the time of writing this. I also learned that putting the charger on top of the power supplies is a bad idea (I know...duh...). I started smelling something awful about 15 minutes into charging and found the duct-tape that I used to hold the power supplies together in a block melting/burning...they got really freakin hot. Unfortunately, despite the separate power supplies, each individual charger maxes out at 50W (~2A for these packs), which implies that it is software limited and not power supply limited. I was hoping to get 5A out of them so I could charge the packs in under an hour...oh well.

Compare the 2 motors' wiring. Also note the massive stack of risers.
I also did a bunch of wire routing. I'm about 3/4 the way done with getting all the motor wires routed. All of the essential inner wiring is complete (in other words, everything but the fans and lights). The nice sleeving stuff I bought works like a charm. Something I thought of is that I could have used ribbon cable or something like ethernet cable for the sensor wires, instead of running 5 separate strands...doing that probably would have made my life easier (yet another lesson learned).

I really really REALLY hope that none of the electronics have decided to stop working. Debugging this system takes forever, and taking apart a motor is a whole day (and destructive) ordeal. We'll see soon enough (queue ominous background music).

Left to do:
1. Finish wiring (3 hours)
2. Design/Make Wii-nunchuck controller (15 hours?)
3. Test and program motor controllers (8 hours)
3.5. Fix electronics problems (I'm 99% sure something will go wrong...it always does)
4. Finish mounting motor controllers (45 minutes)
5. Test ride around a little inside (10 min)
6. Cut/Glue polyurethane tires on (24 hours)
7. Test drive
8. Install fans (5 hours)
9. Install lights (20 hours) (optional)
10. Waterproofing (4 hours + drying time)

Estimated work time left on project: ~80 hours (including lights)

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