November 2011


Pavement dried out. The acceleration is stretching the front suspension upward
nicely.

98.44kw so far. Getting there. I bet any sagging is caused by the pack.

I’ve got the pack doing better. But now it’s raining. Anywhere from 0-10 mph I
can spin the tires right up in the rain! More testing on dry pavement will force
more current from the system. That will let me know how close to 100kw I am.

My old faithful Fluke 83 from the mid 1990’s had a display problem that is sometimes described as ghosting. It was much lighter in color than normal. Some segments were nearly faded completely away. I found this thread. All I did was take a polymer eraser, the white ones from many mfr’s, and cut it to a more pointed shape. Then carefully cleaned the places on the circuit board where the lcd makes contact. These contacts were made visibly brighter by the eraser. I then cleaned up the contacts for the push buttons as well. They were never a problem, but worth the cleaning since I was in there anyway. I cleaned the carbon tips of the buttons gently with the eraser as well. I never took the old original pink elastomer off of the lcd nor did I clean the lcd. Just gently cleaning with the polymer type eraser of the pcb contacts was all that was needed. The display has never looked so bright and crisp!! We will see how long this repair lasts!

There is a replacement kit on Ebay from a vendor named A-fluke. The kit these days is about $24USD. It supplies instructions and the newer gray elastomeric parts for the 80 series of Fluke meters.

Some prototyping netted 91kw of output from my truck recently. The acceleration was unbelievable. That’s still an 80% improvement. The pack is sagging more than normal right now. So I’m correcting that as of now. I suspect that would be worth a few more kw. Looking forward to 100kw soon as the pack gets updated and the R & D progresses.

The data sheets say the factory igbt’s are rated at 400 amps. Almost there now. If I can keep the pack above 250vdc at 400 amps, then I’ll be at 100kw.

I have had an igbt/hv buss redesign going. Might have to put more priority into that since the factory igbt’s are nearly at their max current rating. Although for maybe only 10-15 seconds at a time, 400 amps may not be a threat to their longevity.

With the A123 prototype modules doing fine, a full pack would have such low impedance that 100kw would be easy to hit. Maybe too easy. Going to build about 12 more A123 modules soon.

My A123 modules got a beating at a combat robotics contest recently. They held
up fine. They were charged with a BMS on each cell. Discharge rates overlapped
my truck. These cells saw far more G-forces than normal. But I needed some
testing on the structural side of the design to make sure nothing stupid
occurred. The spot welds were of particular interest. The owner uses A123’s in
his robot. Now he’s sending 100 more for more packs to be made. Sweet. This time
however he has a different module layout he wants to try.

I used nickel as the conductor since copper is apparently next to impossible to
weld with a CD welder. I was told this and didn’t believe it. Then I tried to
for 3 days. Nope. Even as fancy as my CD welder is. Nickel is universal for cell
assembly. But not only is copper cheaper, it also is a better high current
conductor. That’s also what makes it harder to weld. It basically has no
resistance. Since I’m making over 70kw now, I have to make sure a module can
pass 100kw for the future (fingers crossed). If copper ever gets used, I’ll have
to buy/make an inverter type welder.

I just won’t be satisfied until I can spin tires on dry pavement at will!