do not have a data trace to calculate kw-hrs used per lap. We
do know that after three laps, our average cell voltage was 3.86.
We fall back to our 70
amp discharge study and estimate that we have used 30% of
the 22.7 kW-hrs or 1.031 kW-hrs per mile. That means we should
be able to go 10 laps at full power. The race is eight laps. We
can race at full power.
Data Acquisition specialist has to use some tricks on the grid
to make sure the computer and inverter are talking. This problem
means there is no time to set up the video camera. The officials
signal 'clear the grid' and we roll out on the pace lap.
warm up the tires by slowing up and then going hard through the
corners. To save power, I only warm the brakes a little.
am out of the last chicane and pointed straight as the pack accelerates
towards the start line. Full on the power and the green flag flies.
My timing is good and the Imp's power pulls us past four cars.
I brake early to compensate for cold brakes. The car starts to
slow, then seems to accelerate again, then slows again. I am closing
too quickly on the car braking ahead. I turn the car to avoid,
and spin. I roll backwards as cars pass on both sides. One car
does not turn fast enough and whacks the left front of the Imp.
traffic clears, I respin the car and aim back onto the track.
The car is running and I hear no odd noises and no smoke. I rejoin
at the back of the pack and begin to work my way back up.
car is running strong. I am reaching over 105 mph at the end of
three longest straights. 600 amps and no cell is falling below
2, according to plan, I start using the regen pedal. This provides
an additional 160 ft-lbs of slowing. Because the car is not stopping
well, I brake early. The car slows way before the corner. I ease
off the brake and then can't get the car slowed down enough to
hit the apex. This happens again and again.
most of Homestead's corners require good braking, corner 8 requires
good grip and nerve. First lap around, I have traffic and must
brake behind a slower car. Next lap, I just breathe the throttle.
Then back to full throttle and turn in. It is bumpy and the car
lifts and bobbles. It settles just in time to brake for the next
corner. My second lap is 2 seconds faster than my qualifying time.
4, coming out of turn 6, smoke appears directly below my seat
again. I pull into the pits. We guess it is another shorted wire
but can not take the chance.
and I confer. The drilled rotors show signs of cracking. The paint
on the calipers have changed color from the heat. The infrared
thermometer shows the front brakes came in much hotter than the
car feels like the throttle is sticking. We check the linkage.
There is no binding or problem. A look at our data shows a number
of incidents of unexplained surges of motor torque including the
surge I felt right before the accident in turn 1. At 1.5 seconds
into the lap throttle is at 0%. Current suddenly jumps from 0
to 512 amps. Torque to 178 ft-lbs. This continues for 3/10's of
a second. Then amps drop to 118 and torque to 34 ft-lbs for another
4/10th of a second. Then everything goes back to zero.