emini

Nelson is going well, we've done 2 runs with the KillaCycle, and are about to do a third. The first was a slow 10.551s @ 115MPH where we found the track is very slippery out of the hole. In the second run we had a ground fault in the motors and the series-parallel shift didn't work, so 9.594 @ 136.37MPH was slower than expected.

We hope to do an 8s pass next.

I'm in Nelson where the KillaCycle is scheduled to run tomorrow (Saturday 6 Feb) at 11:30 at Motueka aerodrome. The experimental "high voltage" motors that blew up at Meremere have been replaced with the record setting lower voltage motors with variable brush timing system, so we should see better times than last weekend.

The 4 & Rotary Show and Shine went very well. Come down to Meremere to see the KillaCyle run, we're expecting it's first run to be about lunch time.

Phil & I presented at LCA2010 this morning. The talk went well, but suffered from not doing a practice run. I guess I shouldn't have been writing the slides half an hour before the talk started. I was late getting the slides together because I got the Mini running yesterday evening! I "just" have to install the instrumentation and bleed the brakes and I'm ready for the open day. Video of the talk and the slides should be available soon.

Bill Dubé also arrived yesterday and chatting with him is great. The KillaCycle arrives in Wellington tomorrow and goes on display at Te Papa on Thursday morning. Bill's free public talk is at 6:30pm on Thursday at Te Papa. See Phil's blog for the rest of the KillaCycle tour schedule.

I've now re-installed 30 of the 36 cells in the rear battery box. I added plates at each end of the box to make the walls flat, so it will provide better compression to the cells. This is working better than with no plates (there is a lip at the bottom where the floor of the box overlaps and is spot welded to the sides, but this lip is only 10mm high), but sadly it turns out Auckland is shut in January, and the cutting department is still on holiday. I improvised with 1mm steel (old computer cases turn out to be good for something) and a plasma cutter. Many thanks to Edward for lending me his plasma cutter, it's fantastic, no home is complete without one. I need to reinforce the outside of the battery box, as it bulges a little when you swash the cells in. I realised this only after I'd put three coats of paint on it :-(

Anthony (woody on the AEVA forum) is in Auckland this week and came to have a look at what I'm up to. He was a great help, passing clamps while cutting, sanding the terminals on all the cells and helping me install the cells. He also pointed out many obvious things that I missed (things like you should hammer cells on the edges and the conical plasma cutter torch is conical, but it still has a flat face which you can use to run down the side of a guide and get a straight line).

Sadly the second battery rack was to complex to finish in time for the LCA Open Day and KillaCycle tour so I'm going to have the same 36 cells and 118v or so open circuit that the car had last time it was working.

I've mostly finished the bracket which will hold the front mount (where front is closest to the front of the car if the motor was in a north south configuration, which means it's on the left on this car). The mount is the black round thing hanging below the pipe I welded in earlier, and I've spent the evening grinding the curves on the bracket between it and the pipe. The bracket needs a bit of tidying up I'll be ready to weld it onto the frame.

In unrelated news, the KillaCycle arrived in New Zealand safely, the Tumanako VC motor controller had it's first drive yesterday in the Greenstage electric Saker (first time that has moved under electric power too!) and I have about a week left to put this car together before I'm leaving for LCA2010 in Wellington.

I've mostly finished the rear battery rack. I need to fold up some feet to lift the rack up off the boot floor, decide how to support the front and rear sections (cantilever from the middle one? more feet?) and devise a way to hold the cells down.

For a while, the rack came with added vice grip.

I once said I should get a load leveller. Well, I finally gave in and got two. I think I did well with $50 Chinese units from Save Barn. After a little fabrication, they hang at right angles and I can adjust everything in comfort. I'm never installing another engine without one.

Part of the fabrication involved a strap with two holes, and the levellers came with a piece that just needed a little straightening. I'm not sure if this steel is particularly hard, or just poor, but it did not take kindly to being straightened.

I'm making progress fashioning the structure between the gearbox and the mount that will isolate it from the frame of the car. I'm using an aluminium and rubber mount from a small Nissan (the round silver and black thing between the tube on the left and the gearbox in the middle).

I've been messing around with the BMS master hardware instead of welding stuff together. I'm trying to send a CAN message and, rather than write my own library from the datasheet, I tried to use Microchip application note AN878. It was easy to adjust so it would compile with SDCC but I seem to have found a bug in the compiler.

Because the PIC is a Harvard Architecture CPU, pointers to code and pointers to data are handled differently, which SDCC implements by adding some extra bits to the pointer. Unfortunately it's possible to loose those bits while casting the address of an SFR to a pointer and assigning that to a pointer array element by index.

With the the bits cleared, the write-to-pointer-target helper will do nothing, leaving the pointer on the stack. When it returns, the rest of the code freaks out because it expects the pointer to have been popped off the stack.

The solution (apart from fixing the compiler bug) is to leave out the cast. It seems that assigning an SFR to a pointer array element doesn't actually need a cast.

BAD	pb[1] = (unsigned char *) &TXB0CON;
GOOD	pb[1] = &TXB0CON;

After many hours of fettling and weld practice, I've managed to weld the reinforcing bars into my front subframe. The motor will hang between these bars and they also provide strength at the front of the frame for cells or other equipment.

My 175A welder took a bit of tweeking to make good welds in 3mm steel. The biggest change that made the most difference was switching from 0.6mm to 0.8mm wire. I think this could also have been achieved by turning up the wire feed on the 0.6mm wire. MIG is a little counter-intuitive, if you weld isn't penetrating and the wire is building up in a large bead on top of the work, you'd think that you have to turn down the wire speed and weld slower so the heat has more time to penetrate. Actually you want to do the opposite, as the faster you push the wire into the work, the smaller the arc, the greater the current and the deeper the penetration. Of course wire speed isn't the only parameter which affects the current.

My friend Philip & I are presenting at LCA2010 in Wellington in January. We're talking about electric cars, the Tumanako project, Phil's dreams and open source. I'm there to talk about the EVD5 battery management system. My Mini and Phil's race car will be on display at the open day on the Saturday. My car will be road legal by then (promise!) and Philip has committed to getting his car moving under it's own electric power!

As an added bonus, the KillaCycle will be on display at Te Papa at the same time.

The world's quickest and fastest electric vehicle on the quarter mile is coming to New Zealand in January.

My friend Philip at Greenstage has organised the KillaCycle team to come out for a tour of the North Island including a few runs at Meremere. This bike is seriously fast, it does 0-100km/h in less than 1 second! It holds the world electric drag record, covering 1/4 mile from a standing start in 7.864 seconds and doing 169 MPH at the end. That's 272km/h.

The confirmed events are thus:

1. Thur 21st - Sun 24th Jan - Wellington, show and talk at Te Papa (Bill Dube, the KillaCycle owner, will be speaking 6:30pm Thursday and 1pm Sunday for 30-40 minutes).
2. Mon 25th Jan - Manfield, show and talk (Te Manawa museum).
3. Wed 27th Jan - Taupo, show and talk (exact location to be determined).
4. Thur 28th Jan - Hamilton, show and talk (Wintec, Automotive workshop D1.01 Avalon Campus).
5. Sat Jan 30th - Auckland, 4 and Rotary Nationals show and shine (ASB Showrounds, Greenlane, Auckland).
6. Sun Jan 31st - Meremere, 4 and Rotary Nationals - exhibition drag race (Fram Autolite Dragway, Meremere).

Phil will announce any further events on his blog.

If you're interested in hosting an event or sponsoring the tour, talk to Philip at philip@greenstage.co.nz

Kevin at Lynx Innovation kindly organised to have my EVD5 Backplane design made. I've stuffed half the components and tested out a few channels and it looks like I didn't stuff anything up too badly. The biggest mistake I made was to specify the wrong hole size for the main header where the EVD5 board plugs in (the rows of white sockets). This is somewhat inconveniently fixed by drilling the holes bigger and then soldering the top and bottom. Drilling the holes bigger destroys the plating on the inside and disconnects the two layers, so you have to solder the top and the bottom separately.

There are a couple of places where I could move traces to increase separation (and reduce the chance of shorts) but otherwise, I'm very pleased. Now all I need to do is order the enclosures and find some elves to assemble everything.

This is my third BMS backplane layout.

• It's too short (I forgot the bms overhangs it's edge connector)
• I'm going to try replacing J101 and J201 with double row headers and put them both on the same end
• At the expense of having all the heat at one end, I clustered all the MOSFETs near their connectors so the tracks don't get tangled
• I haven't attempted to bring the heat through to the back side while still preserving all those tracks running under the MOSTFETs, putting J101 at the other end ought to help
• This would do 10 cells, I'll actually print it 2 or 3 or more up to get management of 20 or 30 or more cells on one backplane

I used kicad to draw the schematic and then do the layout. The last time I did something like this was 10 years ago and the free tools were fairly primitive (and crippled) and I'm very impressed with kicad, it even has an autorouter!. The autorouter only deals with two layers at a time and needed a little help to finish this board, but I can tell you it's really satisfying to see most of the tracks appear automatically. There's even a version for windows!