Information on this blog is raw and sometimes unverified reporting straight from the road by teams. The event will issue a media release for any events requiring an official notification.

Note that links in blog entries are not maintained, so while a link may be verified to work on the day of publishing, this is not guaranteed beyond that day.

Wednesday, October 24, 2007

Leeming SHS: Challenge day 1: 21 October

I'm usually up with the ridiculously early group on the first day of the challenge, but this time not: I get up at a relatively civilised 6:45. I pack my stuff, breakfast, and join the team bus which is ferrying students to the start line. I find our support vehicles and lurk there. There are things happening over at the start line, but I can't see them from here. Cars are leaving the start line at one minute intervals, and we get to see them briefly as they zip past. We can recognise enough of them to figure out where they're up to on the list, and so know when to come out and prepare to join up with our car. We're parked in, but we're a four wheel drive so we don't care. Kormilda are directly ahead of us, but their support vehicles are nowhere in sight: presumably they're either lost, confused or parked in. Hammerhead comes by; Steve Morgan in our lead vehicle towing the solar car trailer jumps in front of them; we, in follow, jump in behind. The Challenge has begun.

The first five intersections are held for us by police, who wave us through. After that we're on the beginning of the Stuart highway, and on our own. We catch every amber light: lead goes through, the light changes, and solar and follow must stop.

We solar for an hour or so, and get good numbers. The current draw is small enough that it looks like we can complete the entire distance on solar power in the time allotted.

Then we mysteriously lose the motor controller. We roll into a side street leading to a few businesses that are closed today (Sunday). We reset it and it comes good. We resume. It fails again. We stop, reset it, and it comes good. We resume, it fails, reset, resume, fail, reset, resume. Each time we try to eliminate another possible source of failure: there are two LCD displays connected to the controls: the first time, we disconnect one; the second time we reconnect that and disconnect the other. We turn the RS485 cable end-for-end. Nothing seems to make a difference, but it's hard to tell because of the intermittent nature of the fault.

We try resetting while rolling: turn off the motor controller, wait for it to fade, turn it on. This works some times but not others. We crack open the RS485 cable and look at both ends. We re-flow solder on the bottom of some connectors. We use compressed air to blow the driver controls board clean. If we had a chicken, we'd sacrifice it to dark voodoo gods, just on the off-chance that this would help.

Two kilometres short of Adelaide River (114km from the Challenge start), it stops, and refuses to go again. This is, to some extent, a good thing: at least now when we get it to go, we can be reasonably sure that we've actually located the fault.

We muck about by the side of the road, push the car back 100m to an area where we can get it off the side, and take the motor controller to pieces. The insides neglect to contain an intermittent connection with a large sign attached saying "Intermittent Connection Here", so we reassemble it.

Trent asks if it could be a continuity fault in the RS485 cable. "Test it," we say. It isn't.

We connect a PC to it, and control it using the PC instead of the driver controls board: it works fine.

Trent asks if it could be a crack in the circuit board. I flex the board. It starts working.

Taking advantage of our luck while it lasts, we solar to Adelaide River. It's a bit short of our day's end time of 5:30pm, but we stop here anyway. We easily refill our batteries to full before the sun goes down: we've spent so much time by the side of the road that they were still mostly full.

If it starts working when I flex the board, it means that either there was some short circuit and flexing the board moved those two things apart so they are no longer shorted, or that there was an open circuit and flexing the board caused those two things to contact. The latter is more likely. Since the board doesn't appear to have any cracks, it might be a cracked solder joint.

I pull the driver control board, look at it carefully under my pocket knife's magnifying glass, and reflow solder on as many contacts I can get to that I'm not afraid of: there's a microcontroller chip in the middle of the board with legs so finely spaced that the solder I'm using is wide enough to cover four pins at once, and I'm too scared to touch that one.

I take it to the car, and plug it in. It goes.

Right now, the car is working. All I have to do is spend a few minutes flexing the board and resetting the controller, and see if it keeps working. I flex the board once. It keeps working.

Before I can flex it a second time, there is a sharp "pop" from the guts of the car, and a smell of burning. I power down, we take the tail off, and a better nose than mine locates the smell: it's the battery safety system. This system is entirely unrelated to the board I've been working on, and the failure seems entirely unrelated too. I have fixed the car, had it working for ten seconds, and it has failed again.

Until now, assuming we could fix our motor controller problems, we might still be able to complete the entire 3000km on solar power: the hardest part would be solaring to Dunmurra checkpoint before it closes. Now, we cannot: without the full lithium battery pack, fully charged, we can't get there in time on solar alone.

Without the battery safety system, we are unwilling to run our lithium battery pack. We can either switch to the spare nickel metal hydride pack we brought (paying a time penalty of several hours for the privelige), or since only one quarter of the safety system is dead, we could cut out one quarter of the battery pack and run at 80V. But our boost tracker can't boost to that low a voltage, so we'd have to reduce the number of solar cells connected into it, and we'd have to increase the number of cells connected to the other tracker, which would take it somewhere close to its maximum power rating. We'll make a detailed plan later.

Challenge day 2: 22 October

At dawn, we set up the solar array, and connect in our old NiMH battery pack, a spare from the previous Challenge. Cloud covers just the bottom of the sky at dawn, but chases the sun up the sky.

At 8am, we trailer forward. In Katherine, we drive past the checkpoint, long since closed. We are allowed to miss one checkpoint over the course of the Challenge: this is it. We continue to Dunmurra, serve our half hour at the checkpoint, and trailer onwards to a point just south of Elliot: a gravel bay just off the road, with no facilities at all.

I drive 30km back to where Willetton are camped: they've had a couple of minor array issues, including a group of cells on bypass. We chat, I explain how to find and fix the problem; they get it.

I return to camp.

We have covered no solar kilometres today.

Challenge day 3: 23 October

We leave at 8am, and continue trailering south. The broad plan is that we will trailer to Alice Springs and fix our woes there.

We reach the Tennant Creek checkpoint, and I get phone coverage. I phone Peter Lewis back in Perth, and get him to locate the chip that has blown on the battery safety system. He tells me that it's only available from one distributor in Australia. Since it doesn't seem likely that we can get one of that chip to Alice Springs by morning, I tell him not to bother taking it further. He posts details to the Sungroper mailing list. Onno in Adelaide picks it up from the Sungroper list and posts it on the World Solar Challenge blog. A parent of one of the team members back in Perth reads the blog, and phones John Beattie on the road in the middle of nowhere: he has an account with the one distributor, and thinks he can get one to us by morning; would we like one? John catches up with me at Ti Tree roadhouse and relays the question; I answer yes. John phones back and sets it up.

We trailer to Alice Springs, under cloud and, at one point, rain. We pass many other teams who are still solaring.

The Alice Springs checkpoint is chaos: Alice Springs have required the Challenge to hold cars here, presumably for local political mileage, and there are officials, teams, cars, and support vehicles are everywhere.

A couple of teams have the same driver controls board as us; I enquire as to whether either has a spare and can stand us a loan. Both have one spare: both are underconfident about the one they have in the car at the moment (one because it's a custom jobbie, and possibly dodgy; they other because it's sitting in the driver's lap). Tritium, the manufacturers are here: they don't have any in stock at the moment. So there are no available spares. I'd better hope that I really have fixed it.

There's free camping at the checkpoint, but with many teams and limited facilities, we figure we'll be better off elsewhere. We trailer to the Mac Donnell Ranges caravan park.

Tomorrow we'll get the replacement part for the battery safety system: if it works, we can keep using the lithium pack; if it fails, we'll switch to the old NiMH pack. And once we have batteries we can use, we'll find out if I really have fixed the driver controls.

Doug Burbidge
Leeming Hammerhead