Model 3 on-track at Laguna Seca: 20 minutes, NO throttling

KarenRei

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#1
https://jalopnik.com/watch-a-tesla-model-3-go-flat-out-on-laguna-seca-racewa-1823532600

Includes a video. Nearly 20 minutes spent racing. 2/3rds of a charge burned through. No power throttling whatsoever. Now, I've expected this, and mentioned it many times here, but it's nice to see it confirmed! The only problem he had was that he completely burned his (friction) brakes out during the run. So if you want to spend time with your Model 3 on the track, put some more durable brakes on it! ;)
 

Michael Russo

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#3
https://jalopnik.com/watch-a-tesla-model-3-go-flat-out-on-laguna-seca-racewa-1823532600

Includes a video. Nearly 20 minutes spent racing. 2/3rds of a charge burned through. No power throttling whatsoever. (...)
Karen, thanks for sharing. Watched about half of it, up to the point brakes started to be ‘scary’... (watching track is like watching tennis... after a while, you kinda would like to be at the wheel... ;))

Couldn’t help but noticing that he seemed to have a particular challenge with the one (right turning) curve before the blue Cooper Tires overpass...

With regards to brakes, trust it is related to weight and inadequacy of stock brake pads for this purpose... Also wonder if you could get a bit of extra longer brake performance by optimal use of regen...

Not that I’m an expert... :D
 

garsh

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#4
Also wonder if you could get a bit of extra longer brake performance by optimal use of regen...
If the 3 offered an option to turn on a much stronger regen setting, it would help. The motor should be capable of regenning past the point of locking up the rear wheels, but that would be bad, so you'd have to dial it back a bit. It would be dangerous for everyday use, but would take a lot of the burden off the brakes for racing, and keep the battery charged better.

The other issue is, would the inverter & batteries be able to handle that much power? The batteries were designed to allow supercharging, so that shouldn't be too much of an issue. But a regenning motor generates alternating current (AC), so the car's onboard charger would need to transform this to direct current (DC) to charge the batteries. Remember, supercharging is DC, so it doesn't involve the onboard charger. The onboard charger is designed to handle at most 48amps, so if tire adhesion isn't the limiting factor, that will be.
 

garsh

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#5
I'm going through the TMC thread. Some highlights:
  • He installed the tow hook. I think you have to have one installed in order to race there. Anyhow, he broke the tow hook cover. So, be careful if you ever decide to remove the cover - it is fragile.
  • He had regen set to low. That's a shame. Setting it to standard would have helped a great deal to keep the brakes from cooking.
  • I have no idea what it means to "blow sound", or why that gets you kicked off the track. :)
 
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KarenRei

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#6
If the 3 offered an option to turn on a much stronger regen setting, it would help. The motor should be capable of regenning past the point of locking up the rear wheels, but that would be bad, so you'd have to dial it back a bit. It would be dangerous for everyday use, but would take a lot of the burden off the brakes for racing, and keep the battery charged better.
Hardware-limited max charge amps 192A, max charge power 46,9kW. Versus a max output of 1200A and 370kW, respectively.
 

garsh

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#8
Couldn’t help but noticing that he seemed to have a particular challenge with the one (right turning) curve before the blue Cooper Tires overpass...
That's the location of the "river" of water crossing the track. It had rained the previous day, and not everything had dried out.
 

garsh

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#9
From 4:00-5:00, watch him reel in that race-prepped BMW. :cool:
And from 6:10-7:05, he catches up to and passes a Porsche! :eek:

Wow. Not once did anybody pass him up through 8:30, which is when the brakes began to fail.
 
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garsh

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#12
But why the surprise that Model 3 has regen?
I was surprised that the onboard inverter can handle 192A AC. That's much higher than the 48A wall-charging limit. I'm still surprised that there would be a different limit. Does regen make use of a different inverter?
 

KarenRei

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#13
I was surprised that the onboard inverter can handle 192A AC. That's much higher than the 48A wall-charging limit. I'm still surprised that there would be a different limit. Does regen make use of a different inverter?
I have no clue how the charger, pack, and inverters are structured internally :) Sorry!
 

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#14
I'm sure he was trying to do low regen so that his acceleration would not be limited, but given that his brakes got cooked, maybe it would have been better to see if the BMS could have handled the heat with hard accelerations and standard regen. How long driving that way before your acceleration is limited? Maybe his acceleration was limited towards the end. I know the Model 3 doesn't have the second binnacle, but it still would be nice to see when the BMS is limiting the acceleration or regen.
 

garsh

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#15
I'm sure he was trying to do low regen so that his acceleration would not be limited,
You mean "due to the motors getting too hot", because that's what happens when you try to hot-lap a Model S. Yes, that does make sense. It'll be interesting to see if a Model 3 is better able to handle keeping the motors cool.
 

KarenRei

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#16
I'm sure he was trying to do low regen so that his acceleration would not be limited, but given that his brakes got cooked, maybe it would have been better to see if the BMS could have handled the heat with hard accelerations and standard regen. How long driving that way before your acceleration is limited? Maybe his acceleration was limited towards the end. I know the Model 3 doesn't have the second binnacle, but it still would be nice to see when the BMS is limiting the acceleration or regen.
If designed right, acceleration should never be limited on a Model 3. Ever. No induction = no induction currents = no rotor heating (for the most part). Stator heating is trivial to lose because you build as extensive of a heat exchanger on it as you want. Rotor heat loss is limited by shape constraints near the windings, viscous drag elsewhere, and the flow rate between them.
 

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#17
I was surprised that the onboard inverter can handle 192A AC. That's much higher than the 48A wall-charging limit. I'm still surprised that there would be a different limit. Does regen make use of a different inverter?
My car charges much faster while braking than it does from being plugged in. Since braking events are usually small chunks of time, the higher limit while braking is likely not damaging to the cells.
 

m3_4_wifey

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#18
You mean "due to the motors getting too hot", because that's what happens when you try to hot-lap a Model S. Yes, that does make sense. It'll be interesting to see if a Model 3 is better able to handle keeping the motors cool.
Yes, motor and battery, but based on watching other videos pushing the Model S/X, it was specifically the stator that got hot.
 

garsh

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#19
Yes, motor and battery, but based on watching other videos pushing the Model S/X, it was specifically the stator that got hot.
I thought I remembered reading that it was the stator. But I wanted to look up the source for that information before I dare disagree with @KarenRei publically. ;)
 

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#20
  • He had regen set to low. That's a shame. Setting it to standard would have helped a great deal to keep the brakes from cooking.
Standard regen may have helped a little, but Laguna Seca will trash most OE pads super quick. Remember, the usage pattern when you're on a track is basically: accelerator to the floor, quick switch to very hard braking, a bit of accelerator feather in cornering, and then to the floor again. There isn't much in the way of 'coast time' for regen to do its thing--you're either on the brakes hard or you're on the accelerator. Repeat 11 times every 2.238 miles, or about 2 minutes.

Willow Springs is probably a better track to run if you're gonna roll with OE pads... it'll just eat your tires instead. ;)
  • I have no idea what it means to "blow sound", or why that gets you kicked off the track. :)
Laguna Seca has strict noise rules in place thanks to people who decided to build very expensive houses nearby. You get kicked off the track if you're too loud.