Trip Stats

Date	July 16, 2018
Stage	2
Start Location	Scotts Bluff National Monument
End Location	The One Mile Hog Ranch Historical Site Marker
Elapsed Distance	approx. 248 km
Start Elevation	1255.4 m
End Elevation	1494.3 m
Elevation Δ	238.9 m
Observer	Chloe Gibbons
Convoy	Micah Bai Devon Copeland Titus Chow Karl Ding Veronica Lee Taiping Li Robin Pearce

Summary

We ended up missing the checkpoint, which meant that we had the same observer for two days.

In retrospect, that could easily have been avoided, had we decided not to drive like maniacs and take everything at 80+km/h. To be fair, we also lost at least an hour in the morning due to issues we were seeing on one of the AFE boards, and so the mood of the convoy was very much that we had to make up for the time we had lost.

The car had immediately BPS faulted (due to the AFE board) once we unloaded and powered on at the Stage Start. We ended up working around the issue by swapping the boards around in the daisy chain, such that the board that needed 12 voltage inputs was on the good board, and the bad input was on the board that needed 6 inputs (luckily the bad input was on the unused portion of voltage inputs inside the slave box). The team also decided to christen the battery boxes as "Bill" and "Hillary" (and made it official with our label printer), as we constantly had to "lock them up", which the ASC officials Brian and Byron got a kick out of.

We also encountered our first test of bad weather, and thanks to taping our panel gaps, we managed to make it through relatively unscathed. The convoy somehow managed to sneak ahead of the thunderstorm that was following us, and so we just barely missed the downpour (barring a few small patches of rain). The trailer wasn't as lucky. We managed to make it to Douglas without any major problems, and then stopped at a large pullout on the left in order to get some additional charge, since our pack voltage was rather low, and there was a giant hill up ahead.

We actually made it quite a bit past the One Mile Hog Ranch Historical Site Marker, but our pack capacity was basically at 5%, and there was a giant hill we had to climb, which meant that we would be BPS faulting. As we attempted to turn the car around on a hill, we set up flags on either side in order to block off oncoming traffic. A giant transport truck was coming down the hill the other way, and started engine braking as soon as he saw us. Further down the hill, the ASC officials (Brian and Byron) were screaming at us to push the car, but we couldn't make out what they were saying, and our radio contact was pretty spotty. After pulling in front of the Historical Site Marker and loading into the trailer, we later found out that because it was an Emergency situation (as the car broke down and needed to be cleared from the road ASAP), it would've been okay for us to push the car and not accumulate any penalties—we had just assumed that because all the other penalties were so ridiculous, pushing the car was equally as bad. It turns out that the penalty for pushing is 2 minutes for every 15 seconds of pushing, which was totally fine for us, given we had trailered during the previous stage.

We also noticed via telemetry Cell Module 11 was about 280 mV lower than everything else in the pack, which reduced our pack capacity by about 10%. Over time, this would get worse, and so we determined that it was worth the penalty of replacing a module instead of continuing on with a reduced pack. For some reason, we never got penalized for this, even though the formula in the regulations seem to indicate that we would've picked up a 13 minute penalty—although it specifies a lap penalty, so maybe it only applies to FSGP (our observer Chloe was also asleep, so she might've not been aware about what we were doing).

The plan basically became that we would find a place indoors so that we could perform the module swap. In the meantime, the backup AFE board would be brought up in case we needed it. Performing the module swap would take time, since we would need to discharge the module to be at the same voltage as the rest of the pack, and then charge the entire pack to full capacity. We would also find another AFE + Carrier board in our spares, and use that to balance our pack while charging via the bleed resistors. So after sorting out some internal team miscommunication, we drove back into Douglas and managed to snag 3 hotel rooms at a 10% corporate discount, thanks to Devon's picture of his Tesla badge.

Unfortunately, we were not able to bring up another AFE board, since we couldn't find all the components. In addition, we couldn't find the old Carrier board, and so even though a rudimentary bleed discharge resistor algorithm was implemented, we never ended up using it. Devon worked on resoldering the connector to our Motors, using the pinout in the WaveSculptor datasheet.

We then took the car and the X to the RV campground in order to charge. Karl drove the X, and Matt and Devon took the trailer. We ended up having to look around in a bit of panic for the Charger board, which turned out to be in the car. Due to the lack of sleep, setting up the charger probably took twice as long as it should have.

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