Trip Stats

Date	July 21, 2018
Stage	4
Start Location	approx. 11 km out of Adrian, OR
End Location	Burns Business District/Arrowhead Plaza
Elapsed Distance	approx. 215 km
Start Elevation	approx. 672.4 m
End Elevation	1266.8 m
Elevation Δ	594.4 m
Observer	Chloe Gibbons
Observer	Spencer Berglund
Convoy	Micah Bai Devon Copeland Karl Ding Taiping Li Adam Marchand Kaitlyn McCluskie Robin Pearce Matthew Suski

Summary

This was the day when we almost blew our only copies of the BMS AFE boards. You can read details in the post-mortem, but essentially, because the voltage taps and thermistor connectors weren't keyed, we mistakenly plugged the voltage taps into the thermistor inputs, and damaged the MUX. Thankfully, replacing the MUX seemed to allow us to get back in business (albeit with no thermistor readings), but it took us out of commission for a good 3 hours.

Other than that, everything went pretty smoothly, and we breezed through to the stage stop. We stopped 2-3 times for the usual Motor Controllers overheating, and then another time for a 10 minute driver swap (and ice cream) break.

There was a minor issue where our Telemetry system was indicating that there was about a 250 mV offset at lower voltages, that eventually became a 400 mV offset between our lowest and average cell voltage in the pack as the pack voltage dropped, which seemed to be indicative of a board issue that we would debug later in the evening at the campground. The people in the convoy collectively deemed this as a non-issue in terms of our pack capacity, as it seemed to just be a linear offset and not indicative of the actual cell capacity, so we wouldn't experience that sharp dropoff when we dropped below 3.5 V. The voltage seemed to be being shared between AUX input 15 and 16, where taking the average of the two would equal the average voltage of the rest of the pack. We basically treated it as a linear offset for when our pack would undervoltage fault, which we were confident we wouldn't hit, seeing as we had more than enough projected capacity to finish the stage.

Later that night at the campground, we ate dinner and had a team meeting about finances. Minnesota was also camping at the same campsite, and a few of us headed over to chat with them and see how they were holding up. They said that they'd finally diagnosed their electrical short issues, and so said that we'd see each other at the finish line tomorrow before heading back to where we left the solar car. We diagnosed the issue we were seeing with AUX input 15/16 before setting the car up for charging. It turns out that there was a cold solder joint on the fuses, and touching that up fixed our voltage readings on those cell inputs

Results

Team #	Team Name	Stage Start	Check Point Arrival	Stage Finish	Penalty Time	Elapsed Time	Miles Credited	E Value	Person km	# External Charges	Q Battery (Wh)
559	Blongna	09:08:00	13:32:36	13:06:57	00:00:00	12:13:57	384.6	0.601	2475.8	0	16800
35	Minnesota	09:06:00	-	-	11:06:12	29:06:12	0	0.287	0	1	6750
828	App State	09:07:00	12:12:23	10:50:37	00:24:00	10:22:37	384.6	0.030	619	2	11025
24	Waterloo	09:09:00	12:40:27	16:21:12	00:02:00	15:29:12	384.6	0.020	825	2	15876

Browser not supported