Tesla, TSLA & the Investment World: the Perpetual Investors' Roundtable

[mongo]

Indeed, plus there's also drag which increases quadratically and is significant at those speeds.

Yeah and power due to drag is v^3 (drag itself is quadratic, but then you get another v due to speed). Energy due to drag per unit distance (t×v) is v^2 (v^2 drag over same distance).

The Raven has 177 kW front motor and a 360 kW rear motor, with 537 kW peak power in theory - in practice probably in the 510 kW range.

If we assume that the Plaid powertrain duplicates the rear motor, that's 177+2*360 = 897 kW theoretical peak power, in practice it will be a bit lower due to the different gearing ratios - let's assume up to ~800 kW peak power can be brought to the wheels, over a broad RPM range - and I'd guess still more than 600 kW at top speed, when the front motor will likely not contribute much an

Gearing does not change peak power, only where the peak power band is relatice to wheel speed.
Dual 3 motors in the back give approximately the same power (177×2 =354, and they can likely do more with a different front/rear power split, no steering angle CV concerns) and likely can also spin the wheels. With an adjusted ratio, that match well with the pack.

The question is whether the Plaid battery pack can output 0.8 MW peak power from a 100 kWh pack: probably not, but if it's a 120-150 kWh pack then possibly yes.

100P ludicrous had pack peak amps of 1,850 (×350? = 650kw) and Motor HP of 680 (×750W/HP = 510kW).
https://www.motortrend.com/news/a-c...sla-model-s-p100d-ludicrous-acceleration-run/
Two rear motors -> better efficiency and thus more output power. Shorter bus bar length in pack (3 style connections) -> less voltage drop -> more power.

This is basically negative power torque vectoring, where generated power from one rear wheel is directly routed to the motor of the other rear wheel, avoiding battery pack charging/discharging loss and heat generation. I'd only expect this to be in play for very short periods when entering and exiting a corner.

I'm not seeing when this would be used. On a turn ,the outside tire gets the most load and is the one you also want to spin faster. So it gets the most work and has the most traction. Inside tire is unloaded and slower. Aero and other drag are still in play, so zero power vs some power gives you turning torque. If accelerating, no reason to regen (less traction), if decelerating no reason to add power (outside wheel). What am I missing?

 

[Krugerrand]

This UAW action is getting ugly.

Bottles of Cristal and steak dinners mark UAW corruption probe as prosecutors detail lavish use of union funds

Who knew?

It’s not like the UAW didn’t use shady tactics like hiring people to stand in for a Tesla protest when virtually no employees from Tesla showed up.

 

[Fact Checking]

Gearing does not change peak power, only where the peak power band is relatice to wheel speed.

That is what I mean: in a 3 motor setup (1x+2x) the different peaks will add up to slightly lower peak power, because the peaks of the front and the rear motors is not at the same RPM.

So the combined "true" peak power will be a bit less than the 177+2*360 = 897 kW calculation would suggest.

Furthermore, for the purposes of the top speed calculation I attempted, there will be a 'high RPM taper' of the rear motor output, even at higher gearing ratios.

The front motor will be even less effective. So it's unlikely that the Plaid drivetrain will be able to produce anywhere near to its top power in the top speed regime.

 

[Fact Checking]

I'm not seeing when this would be used. On a turn ,the outside tire gets the most load and is the one you also want to spin faster. So it gets the most work and has the most traction. Inside tire is unloaded and slower. Aero and other drag are still in play, so zero power vs some power gives you turning torque. If accelerating, no reason to regen (less traction), if decelerating no reason to add power (outside wheel). What am I missing?

I agree, and I don't understand SoylentBrown's fascination with negative torque vectoring either, which is why I said "very short times" - such as when transiting between a left and right corner in a tight S-turn, you'd want the car to turn into the new corner and brake the right wheels - instead of mechanical braking it could be regen-braked and the left wheels would accelerate - which would probably turn the car faster and more efficiently than via steering alone.

But that's a really narrow case AFAICS. But then again, my racing experience ends at racing Go-Karts.

 

[Fact Checking]

Yeah and power due to drag is v^3 (drag itself is quadratic, but then you get another v due to speed). Energy due to drag per unit distance (t×v) is v^2 (v^2 drag over same distance).

So the Model S's ~31.3 kW drag at 100 mph increases 9-fold to ~281 kW at 200 mph?

I'm wondering why the Raven can "only" go 163 mph (262 kmh)? If it has a power output of ~500 kW, then even with higher RPM taper there should in principle be plenty of excess power left to overcome 281 kW of drag plus rolling resistance.

 

[Unpilot]

I come here to learn and as the preceding discussion has left me befuddled....I feel like I'm at a party with a bunch of scientist's.

When asked what I think I reply "yes I think so"

 

[MC3OZ]

Braking one side should have a similar effect to accelerating the other side, relative speeds are what help make the turn.

I'm not a expert, so I could be wrong.

If this can happen peddle input brake or accelerator must set the bias.

 

[Dreadnought]

Yes
Like Zis.

Except now with spacex package, while the car is doing the not-a-donut in place. The thrusters boosts the car in the direction you want to travel. Creating a frictionless sliding not-a-donuting maneuver, like a hockey puck on air hockey table.

Neat idea. Even more fun with a "print to street" button on the sketchpad to render graffiti on the tarmac.

 

[HG Wells]

Look at that Escargot!

Gary? Wrong company.

WHAT DID YOU DO WITH GARY ?

 

[JRP3]

Porsche Promises World-Beating Hypercar With Help From Rimac
Porsche getting their ev tech from Rimac.

 

[jerry33]

After a couple of weeks vs a day/couple days butts in/out of seats all day at Frankfurt auto show.

Plus the ventilation holes in the pleather in the Tesla caused rips.

Either way most people buy vehicles to use for many years/km and both light colored seats would be a PITA to keep clean.

I agree that white seats would be a cleaning nightmare, but the light grey seats in the 2013 still look clean after 126K miles. I'd wish they would bring back that colour and ditch white.

 

[ZachF]

Drone strikes set Saudi oil facilities ablaze

Attacks on Saudi oil facilities

 

[Silent Ludicrosy]

So the Model S's ~31.3 kW drag at 100 mph increases 9-fold to ~281 kW at 200 mph?

I'm wondering why the Raven can "only" go 163 mph (262 kmh)? If it has a power output of ~500 kW, then even with higher RPM taper there should in principle be plenty of excess power left to overcome 281 kW of drag plus rolling resistance.

No, it’s 8x31.3=250.4 kw. (200/100)^3=8

 

[Artful Dodger]

Drop a few supercaps in there to buffer the energy transfer between motors and you'll have a winner

Please Mind the Gap. Also:

Thank you.

 

[Pezpunk]

I think this is a fantastic idea. Maybe he should file a patent for it!

And he would likely be granted one. It’s not the patent office’s job to determine if an idea will work, only to ensure that it meets certain requirements such as uniqueness and non-obviousness.

 

[Fact Checking]

And he would likely be granted one. It’s not the patent office’s job to determine if an idea will work, only to ensure that it meets certain requirements such as uniqueness and non-obviousness.

A good patent examiner might reject the patent application, because it does not meet the requirement that a person "skilled in the art" would be able to re-create the invention.

In practice many nonsensical patents will slip through though.

But to describe a working invention with at least one working implementation ("embodiment") is also necessary for the patent to be enforceable. The most valuable part of a patent is "Claim 1", which, if it covers a broad range of devices, will cover a lot of products and can thus be very valuable. But if, due to a patent drafting mistake, the "embodiment" is not actually possible to build, defendants will challenge the validity of the patent on the grounds that it cannot be re-created as described - and have a good chance to prevail.

So while a patent describing a Perpetuum Mobile might slip through and might get issued with a ridiculously broad Claim 1, its actual value is very likely near zero, unless you invented the Epstein Drive that is.

 

[UncaNed]

Don't know if anybody has focused on this, but I thought it remarkable that yesterday's charges against the UAW center on UAW's Region 5, which covers 17 states, including California and Nevada.

These are the folks who are trying to organize Tesla.

U.S. corruption probe involving lavish parties, champagne hits another top UAW official - Reuters

That might have been our Tesla investment dollar in the pockets of union officials had Tesla unionized.

 

[UncaNed]

So the end of quarter push is on in the U.S., according to Fred:

Tesla allows discounts and offers 2 years of free Supercharging for end-of-the-quarter push - Electrek

"Sources familiar with the matter told Electrek that Tesla has authorized its sales staff to offer two years of free Supercharging for new Model 3 orders that get delivered by the end of the month, which coincides with the end of the quarter."

"Furthermore, they are also authorizing sales staff to waive the fees of up to two features to match orders with inventory vehicles, which can result in important discounts."

"The features are limited to paint colors, interior, and wheels."

"For example, you could be ordering a Model 3 Standard Plus in white with 18-inch wheels for $38,990 and if Tesla happens to have the same Model 3 in red with 19-inch wheels, Tesla’s sales staff can approve the sale of the vehicle for the same price. That would result in a $3,500 discount over the price of a Model 3 Standard Plus in red with 19-inch wheels."​

Both of these are strong incentives - stronger than the end of Q2 incentives were.

This suggests that Tesla is not happy yet with the number of U.S. customers lined up in the next two weeks (i.e. lower demand than desired), at least compared to Q2, or that they have some sort of imbalance in inventory (too many AWD or too many SR+ units, etc.) which they'd like to flush by the end of the quarter.

...and/or they want to clear stock inventory before some sort of hardware updates...

 

[Navin]

This tesla solar subscription for commercial players is very interesting. A few questions:

Was this pay as you consume structure for commercial accounts known or was this a surprise?
When Tesla signs up a new commercial customer - is tesla working with a 3rd party finance company to pay for the equipment and then collect part of the lease/rental payments or is Tesla picking up the hard and soft cost of the solar equipment and install directly?
Any ideas on how the margins look like here? Knowing that subscription revenue is very sexy to wall street (i.e. Apple, Netflix, etc) -- this could have a pretty profound impact on the way the market calculates TSLA's EV...

 

[mongo]

There's a neat trick on the Roadster 2 though: they can use the SpaceX cold air thrusters to double the grip for the first ~2 seconds: a ~2 tons car that has eno (rest chopped by phone/site)

using the the thrusters for vertical force only makes sense if your coefficient of friction is > 1. Otherwise, you are better off using the force directly. It will plant the car, which is good esp over a dip, but if you want cornering assurance, nothing beats guaranteed force vectors 90 degrees to your direction of travel.


Regarding powerbands: the S/X D versions put the efficency sweet spot of the front motor at highway cruise speed for range. The a plaid version can de-optomize that to flatten and/ or extend the total power band instead. Peak power only matters if you spend your time at that speed. Totally performance depends on overall speed and power profile.

SR also have a flatter powerband that can increase at high RPM. Not sure how the PM side interacts with that.

Dual rear motors: Along with torque vectoring, dual rear PMSR mean that they don't need to use the brakes at all for traction control or ABS up to the regen power limit. More efficiency and controlability gains.

No, it’s 8x31.3=250.4 kw. (200/100)^3=8

I think FC may hald meant 65 MPH (criuse 100kph?) vs 200 MPH, unless they have a good Wh/mile number for 100MPH.