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Should track mode 100% regen be stronger than normal driving?

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tm1v2

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Oct 18, 2021
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Should the 100% regen setting in track mode be stronger than normal driving regen? October 2021 build M3P, if that matters.

I briefly tried track mode for the first time. 100% regen felt about the same as the car's normal regen to me. I thought I read somewhere that 100% regen in track mode is stronger than normal, but if so it wasn't immediately obvious. SoC was around 58% so plenty of room for adding charge. I was just going downhill on a local road, haven't tried it at high speeds yet.

Track Mode V2 doesn't really answer this question. I guess 100% really just means 100% of normal mode, and if track mode supported stronger regen, the slider would go up to 150% or 200% or whatever the relative limit is? 🤔
 
Okay maybe I just need to push it harder to really feel the difference. This was a very casual drive, residential road, not the place for any antics.

Waiting for PPF appointment before doing any serious driving. 🤦‍♂️
 
85kw street, 120kw track mode. It's in the highlighted box on the left side. Top pic is track mode.

Screenshot_20211103-184027.png



Screenshot_20211103-184012.png
 
I hope that Roadster will have hybrid brakes - increase regen until it's limited and only then add mechanical brakes. That and some super capacitor buffer and you can get say 1500kw regen (maximum motors power). With proper battery cooling that should help mechanical brakes a lot on the track...
 
435 kW max discharge power ~= 583 HP. I assume that's before losses because I don't think a Model 3 Perf has dynoed quite that high.
That's how much power the battery pack can put out, not how much power the motors will consume. It's hard to compare a two motor car to a single motor car dyno. If you measure the peak of both motors, the most I've logged is 628hp combined...but (big but) the motors are mapped out to overlay where they both hit peak power at different speeds, which mean technically it's never actually 628hp, it's 480 or 520 or whatever the nominal number comes out to be.
 
I hope that Roadster will have hybrid brakes - increase regen until it's limited and only then add mechanical brakes. That and some super capacitor buffer and you can get say 1500kw regen (maximum motors power). With proper battery cooling that should help mechanical brakes a lot on the track...
You can't charge batteries at 15C, which is the whole reason we're limited to about 125kW right now (magically about the same as a supercharger). As you say, you'd need capacitors to store this- which would add a lot of weight. 1500kW for 5 seconds is 2kWh. Supercapacitors are at about 15wh per kg. So only an extra 130Kg of caps. That's a lot heavier than better brakes. And to even use that 2kW would require some additional power electronics as that energy is only available over a very wide voltage output range of the caps.
 
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You can't charge batteries at 15C, which is the whole reason we're limited to about 125kW right now (magically about the same as a supercharger). As you say, you'd need capacitors to store this- which would add a lot of weight. 1500kW for 5 seconds is 2kWh. Supercapacitors are at about 15wh per kg. So only an extra 130Kg of caps. That's a lot heavier than better brakes. And to even use that 2kW would require some additional power electronics as that energy is only available over a very wide voltage output range of the caps.
Well, for Roadster it would be 7.5C, not 15. And short-term that charge rate is doable today. Yes, it's not very effective for charging, but it can work. And we don't know 4680 DBE capabilities yet.

Ability to use full motor power to brake is a big thing - it's not only about saving mechanical brakes, it's also about quality of braking traction and ABS/TC capabilities are on another level then. At least below 100mph (above needs more braking power than motors can survive).
 
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Well, for Roadster it would be 7.5C, not 15. And short-term that charge rate is doable today. Yes, it's not very effective for charging, but it can work.
It's not "short term" if you actually want to use it on a track. You'd be putting something like 50% of the energy back into the pack. You'd either be at 7.5C discharge or 7.5C charge, which is brutal.

As for 7.5C, who doesn't want a sports car with 2,500 lbs of batteries...

Ability to use full motor power to brake is a big thing - it's not only about saving mechanical brakes, it's also about quality of braking traction and ABS/TC capabilities are on another level then.
Has Tesla confirmed 4 wheel independent motors for the Roadster? Because if not, you can't use motors to do ABS/ESC as those need per-wheel control.
Beyond that, has Tesla confirmed 2000 HP (1500kW)? I mean, the Model S weighs more and is already pretty traction limited by street tires up to about 100 MPH.
 
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It's not "short term" if you actually want to use it on a track. You'd be putting something like 50% of the energy back into the pack. You'd either be at 7.5C discharge or 7.5C charge, which is brutal.

As for 7.5C, who doesn't want a sports car with 2,500 lbs of batteries...


Has Tesla confirmed 4 wheel independent motors for the Roadster? Because if not, you can't use motors to do ABS/ESC as those need per-wheel control.
Beyond that, has Tesla confirmed 2000 HP (1500kW)? I mean, the Model S weighs more and is already pretty traction limited by street tires up to about 100 MPH.
Look at racing drones - they go beyond 7.5C quite often. Their batteries don't live long, but they are not Tesla. At the end of the day, you can add a resistive radiator and throw away some energy if you can't keep it. You still going to benefit from motor braking. Largest trucks do that for a long time - diesel generator, electric motors and motors braking with resistive radiators.

There is no confirmation about 4th motor, but it would make a lot of sense to use to do so. And to be a halo car with Plaid available, you would need to bump the power up significantly.

CG is more important than weight. With compact carbon chassis and 4680 pack it can stay within m3 weight, but have even lower CG.

Plaid is not traction limited up to 100mph. It's up to 50mph. And if it had a racing aero, it would be limited only up to 30 maybe. You need like 15-20MW power to be traction limited on average track. And if you have that, you still can add more aero, more traction and require more power. We're very far away yet from being actually traction limited on the track.