Race Day 4: 28 October 2009

Alice springs to SA Border

Repaired some structual damage to the array bus bar supports. With no proper materials we had to improvise: 5 minute epoxy, balsa, and Chux Multicloth as a fibreglass substitute. The chux is actually fairly strong in one direction, and with three layers soaked in 5 min epoxy, the result was remarkably strong!

We found more significant structrual damage from running off the road, the center body supports had been ripped from the chassis, but it is still supported at each end. It's not ideal but it should be fine.

Arrived at Alice Springs control point at 8:30, unloaded the car, and moved into the official stop at 8:48, did our 30 minutes to start at 9:18. The officials agonised over our late arrival last night and decided to apply a time penalty of 6 hours, to be taken at the end of the race in the interests of keeping us moving. They don't make the crazy rules, so they did their best. We couldn't care less, since we are trailering, and are ranked on distance anyway, and frankly we don't care how they sort their results, we are here to drive the solar car.

There were 5 other cars in the control stop at 8:30am, Aurora 101 (no trailering), Solar World one (no trailering), Esteban, Kelly, and Willeton. We were having trouble with the radio PTT again, and we still had to put on the rear wheel spat, so we planned to stop immediately after the control point. When we came to set off we found the motor would not go either, despite testing ok this morning! Several more broken wires were fixed to get the PTT going, and we eventually traced the controller problems to a bad joint on the controller enable switch. All was finally fixed and ready to go at 10:45.

After all the morning's drama the rest of the day went textbook. We had a full charge from the delays at Alice, we even had to switch the array off. Once again on a constant battery current strategy we hoped to make the SA boarder that night. There is now a 10 minute control point at Kulgera 20km from the SA boarder, and the next one is Coober Pede (30 min). Now with good sun the array power was amazing, peaking 30A into 50V, but mostly around 25 in the middle of the day. The sky was clear, and there was no wind all day.

We managed 50-60 kph most of the day, saving power for the late afternoon. We arrived at the SA boarder at 4:57, with the batteries down to 11.3V per 12V battery. Perfect after maintaining a fairly constant speed. We used all the power we got, as efficiently as possible. Our lead acide batteries on have 55Ah rating, and we got 40Ah out of them today from full charge to almost flat. That's less than 2kWh, so we're hoping for a full charge this evening and tomorrow morning from an array that gave us 1500W peak today!

I used the GPS Altimeter a lot today, and it was very usefull to help corrolate the expected power use with slope, and to identify the hills on the route altitude plots.

No work on the car this evening! Just charging from the evening sun. What an easy evening! Nice. I can even blog!

We are hoping for a clean run tomorrow, start at 8am, and run the perfect strategy to reach Coober Pede by the end of the day. The weather is meant to be good too! After that we will trailer to Adelaide on Friday to complete the global green trailer race.