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Chassis CAN Logging To ASCII Text Plus Graphing

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#541
This one is a bit better, this was my first run where I got a timing error on my last lap! 5 laps, I was pretty tired and not looking forwards to another set. I guess I am glad I got another run since my second run was much faster. I don't really feel bad that I lost, I might have felt a little worse if I had won on my rerun since I was something like 5 seconds slower on my first run 49.XXX on the 4 laps I saw vs 47.xxx for the first three on my rerun
upload_2016-3-28_13-16-4.png


I left all the data in this but did the same compression between data sets
 
#544
apacheguy said:
So 85Ds certainly aren't battery limited. Are they motor power limited or software limited?
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Well, the Tesla Torque spec for a 90D (two small motors) is 485 ft lbs (presumably combined), or 242.5 ft lb for each motor. The graphs above are showing about 230 ft lb for the small motors. So if (all of)
A). The 485 Tesla spec is accurate as a hardware limit in the DU
B). The torque split is equal (appears to be from the data)
Then we are seeing performance plausibly close to hardware limits (no doubt protected by software as well).

NB: the Tesla torque spec for the 70D (which I assume is the same hardware as the 90D) is shown as 387ft lb (presumably combined). This would appear to require a significant software limitation, and suggest a feasible "tuner" upgrade path to 90D performance via a non Tesla firmware upgrade.
 
#546
Andyw2100 said:
Am I reading this correctly?

After an almost five minute long race, the difference between first and second place was 65/1000ths (so less than 1/10th) of a second?

That's incredible!

Edit: If this is correct, just go get a haircut before the next race, and you'll smoke him!
Click to expand...
Ya. Brutal! If we were both on the track together we would have probably came out of the last turn lined up then he would have pulled ahead at the finish line since I am power limited on the last couple of laps and don't quite get up to speed.
Last spring he got me by 9/100hs of a second! 2 years back to back - That's even more incredible! Same track conditions same tires. P85=M3? In autocross I think they match up pretty well in stock form
 
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#551
The 70D has only 14 modules compared to an 85 pack's 16. That's approximately a 50 volt loss, so this contributes to a lot of the lost performance, but according to my back-of-the-napkin, they are also artificially limiting it beyond the simple loss of voltage. They probably want a larger gap for marketing reasons.
 
#555
The track is a go kart track but it is used for autocross too. ~ 20 feet wide asphalt with concrete rumble strips corners, extremely fun track

course is here -https://www.google.com/maps/@42.4167245,-122.8036555,259m/data=!3m1!1e3?hl=en

there are mostly dash cam race videos in this thread nowadays Zextraterrestials S (tory)

The logger was set to 75% throttle and it seems to have been logging only 2-3 seconds for most of the 'events'. Looking at the timestamp from start to finish I think I actually got the entire run - 5 min on the logger and the speeds seem to confirm it, there are 2 straights where you can get up above 60 mph and with the start + finish that is 11 higher speed events which looks right on the first race. The first graph I posted was only part of my second race. It was after the first one in the logger and I assume the file was full
 
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#556
I did some fun analysis on someone's 85D acceleration run and thought I'd share
If someone wants to, they can update with rolling and aero drag.
I calculated acceleration by taking vehicle speed change by time change.
There was lots of aliasing in the data so I did a moving average of like 27 samples
Also estimated vehicle weight at 4950

Also need to calculate % slip, compare motor rpm to vehicle speed. It may be the vehcile speed comes from motor RPM, actually likely, which means that vehicle speed will be overestimated
Capture.JPG

breser - March 27 - Launch.xlsx
 
#557
Did some range mode testing today with the 85D. If the car finishes charging before Elon gets on stage I'll go do some launches.

I'm not going to post any graphs but the data is up on my Google Drive (today's range spreadsheet):
Tesla Logging

Based on this testing I'd say that the 85D always turns off the rear motor and uses the front motor regardless of speeds from 30 - 70. There is some peculiar data in the 60 speed test where the rear motor is showing -0.1 torque but I'm guessing this is a rounding error.

I'm sure you guys will have fun with these data. Might give you something to do while Elon is late.
 
#558
More interesting tidbit. Went back and looked at my 55 mph non-range mode run from the first spreadsheet. In that case the rear motor was on and the front motor was off. Looks like in the 85D at cruise range mode toggles between front and rear wheel drive. Tesla must think one of those motors is more efficient. I'd guess a gearing difference?
 
#560
In both your graphs above, it's interesting how the torque from the front and rear motors are closely matched and declining together until around 3 seconds, when the rear motor has a surge in torque.

I wonder why this surge occurs or if it really does occur? Maybe it's an anomaly in how torque is measured because the battery voltage and current are flat during this surge. It's probably not related to traction control in any way since traction limiting ends before 2.5 seconds.

I noticed the opposite in my P90DL graphs - the front motor has a slight surge in torque around 3 seconds while the rear torque continues to smoothly decline.
 
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