March 25, 2005

Moroso Test Day -Friday

Session 2

For the driver, EV race testing is more like a Formula 1 qualifying lap than any other racing situation. We are very limited, by battery capacity, to how much time we can spend on the track.

The 'Out' lap needs to be hard and aggressive. This brings the tires up to temperature fast. I need to take some chances because I need to know where the limit of tire adhesion is.

If I go too deep and screw up the corner, that is all right. This lap is not about the perfect lap time, it is about learning what the car is capable of.

By the end of the lap, the car needs to be fully warmed up and the new limits known.

The timed lap needs to be as close to a perfect lap as possible. Take the car to the limit, but not over. I also need to be lucky with traffic, not catching any slower vehicles or having to pull aside for faster cars. Ideally, I don't want to even draft any other cars since that will bias the results.

The 'In' lap still needs to be driven at full power to make the total Kw-hr reading close to the same for all three laps. This also gives a more accurate reading for tire temperatures and tire pressures. This is my chance to think about what the car needs to go faster. Is the brake balance right? Does the car need to turn in better? Is the car still oversteering?

This session, the 'Out' lap tells me the turn-in oversteer has been substantially reduced by the anti-roll bar change. I can still rotate the car under braking but it is less twitchy.

I am aware that the tire grip feels odd. It is hard for me to identify but no matter how hot I bring the car in to the apex, I end up having to drive, rather than drift, to the exit berm.

The only corner where this is not true is turn 6. This corner is deeply cambered at the apex and then flattens out at the exit. I find that if I just keep the pedal flat as I turn in, the camber helps turn the car. As the camber falls away, the car loses grip and drifts out onto the berm. This is a bit of a ride!

The chicane is horrible. The entrance is OK but it leaves the car with a tight 90 degree right turn. I know from other drivers that they purposely use power to flick the rear end around and get the car pointed in the right direction.

With all wheel drive and low power this does not work for me. It also helps identify my handling problem- At 1/3 power, my tires give me more grip than I can make use of.

Coming onto the start of my timed lap, I catch two Moslers going slowly through the turns. It is unclear what they are doing and I waste too much time getting by them. This makes my timed lap a 2:08. I consider staying out another lap but again hit traffic and decide to pull in.

Interestingly, after the weekend, we later learn that one of the cells is having a problem.

Before the run, cell #17 was sitting at around 3.763 volts. There are a number of cells reading lower resting voltages (example #53 at 3.704 volts).

108 seconds into the run, #17 drops to 3.406 volts while the cells around are at low 3.6 volts or high 3.5's.

Next reading at 136 seconds into the run #17 is 2.378 volts below the absolute minimum allowed of 2.8 volts under load.

At 164 seconds, Cell # 17 is not under load and has recovered to 3.490 volts. This is the last time it will read above 3 volts. The cell rapidly drops to close to 0 volts and remains there for the rest of the session. This means around two laps are run with a very dead battery without incident.

Since the BMS software was told to ignore any battery below 2 volts to keep the display clear of '0' readings from cells with blown fuses, the dying cell was only displayed briefly and I never noticed it. Only afterwards, looking over the data do we discover that there had been a problem.

Power consumption is 1.412 Kw-hrs per lap or .628 kw-hrs per mile.

This would mean 19.8 kw-hrs for a 14 lap race.

Count in a pace lap and a cool down lap and we might just make this distance.

Our timed lap was a 2:08 but how much time was added by the traffic?

Top speed is 93 MPH.

 



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March 25, 2005 Session 1
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