Predictions on P85D+ performance figures?

[Saghost]

You know, I've wondered about this as well. Maybe you can answer a couple questions I have.

1. When I go out to the car in the morning and open the door I hear a click-click. Is that the battery contact engaging? People have reported failed main packs before presumably because the contactor got "stuck." This happens while parked.

2. If the answer to 1 is yes, then I don't see why heavy acceleration has any effect on the contactor itself. So when the car is driving the contactor is presumably already engaged. It seems that it would be a fuse rather than a contactor that would blow out under high current load.

I'm probably not the best person to answer this - I have no personal experience with the Model S, and everything I know about it comes from reading this forum.

The contactors certainly are closed before you start driving - they have to be. A high voltage contactor is something like a relay - it is spring loaded and usually sits open, isolating the high voltage battery from the world for safety. When the computers say it's okay, 12V current is directed to the contactor, which pulls it closed and allows high voltage power to flow.

Normally you'd think one it was closed it would stay closed for the drive.

However, the 'balloon squeal' noise under hard acceleration that some (but apparently not all) Model S cars exhibit has been described a few times as being from the high voltage contactor (which it could only produce by some sort of partial cycling,) and there are a couple threads that have the clunk power failure being followed by a battery replacement where they were told it was the contactors that failed.

The fact that all of these failure stories have the car shutting down within ten or fifteen minutes after losing the high voltage battery (and then being unrecoverable until jumped) led to the battery/DC-DC converter speculation above. No other car I know runs out of 12V power that fast unless the battery is already run down, and a drained 12V battery combined with more load than the 'alternator' (DC-DC converter) can handle will shut down the car. (I've read that Model S 12V batteries are smaller than most, but never seen an actual capacity rating for them.)
Walter

 

[mgboyes]

Accelerating a 2.2 ton object from stationary to 60mph in 3s can be achieved with a constant 270kW (an in impossibly ideal world where everything is lossless and with infinite traction).

In the real world I believe if 0-60 time was the sole target, Tesla could build a Model S that can hit 3.0s without peak power draw from the battery exceeding whatever it currently is in the P85.

However 0-60 time is not going to be the sole target. Sticky tyres get great 0-60 times but are bad for fuel economy. In the real world 30-70 times are often more important to how people perceive a car's performance.

Seems pretty clear though that if Tesla want to take 0.5s off the 0-60 time of a P85 they could do it with the current pack, a second motor and drive inverter, and some other relatively minor changes.

And if the additional cost to them is $10k but they can add $40k to list price as a result i.e. get $170k for a fully loaded P85D+, they might just do it. It's all about making money now from idiots like us to fund the Model III after all

 

[Perfect_Flaw]

If someone actually paid $170K for an AWD Model S, then yes, they would be an idiot. No way the car is that expensive. Something tells me it won't be more than a $4500 option.

 

[mark]

If someone actually paid $170K for an AWD Model S, then yes, they would be an idiot. No way the car is that expensive. Something tells me it won't be more than a $4500 option.

I think you are delusional - 10-15k minimum IMO.

 

[Martini]

Has there been any speculation about whether two motors sharing the load will increase the time before heat build-up limits power? Seems like two motors sharing the same total KW would heat up much more slowly than one.

Also very curious about the "virtual second gear" that is possible with two motors that are differently geared. Higher top end plus more endurance would be a bigger benefit than faster 0-60 times.

 

[brianman]

It's all about making money now from idiots like us to fund the Model III after all

If someone actually paid $170K for an AWD Model S, then yes, they would be an idiot. No way the car is that expensive. Something tells me it won't be more than a $4500 option.

Can we move away from calling people idiots? If you can't make your point without name calling, then that's a failure in presenting your argument.

 

[RobStark]

I think you are delusional - 10-15k minimum IMO.

The premium for the Model X over Model S is at most $6400. Since Elon has stated repeatedly the price premium will be single digit percentage premium.

For that $6400 you get dual motor AWD, Falcon Wing Doors and third row seats as standard.

 

[Saghost]

The premium for the Model X over Model S is at most $6400. Since Elon has stated repeatedly the price premium will be single digit percentage premium.

For that $6400 you get dual motor AWD, Falcon Wing Doors and third row seats as standard.

Ahh, but the quote has always been a "comparably equipped" Model S. If there's an AWD Model S, that'd be the one you'd compare with an AWD Model X, wouldn't it?

It seems to me like they could choose and price for AWD they wanted and still meet the promise (though if it's a *large* difference it'd probably get people mad despite technically meeting his promise.)
Walter

 

[derekt75]

Model S is limited by torque up to a certain speed, after that, it is limited by power.
For the P85, the change happens around 40 mph, as indicated on Sagshot's plot.
I imagine that in the constant power range above 40 mph, the battery (or battery longevity) is the limiting factor, and a 2nd motor won't help.
In the constant torque region below 40 mph, I would think that a 2nd inverter, 2nd motor, and 2nd pair of tires would help significantly. The front tires can't exert the same amount of force as the back tires as they'll carry less weight during acceleration, but they can certainly help some.

I find no physics fault in Sagshot's "guess", but I would be surprised if it's that good. If it is that good, I'm sure it won't be cheap. but if it is that good, then paying $170k for it would not make you an "idiot". $170k for 3.2s 0-60 is a relative bargain. and a lot of those 3.2s 0-60 cars don't have adaptive cruise control, either.

I'll guess AWD measures 3.8s, with no particular justification for my guess other than:
it should be faster than the current P85,
3.2s is about as fast as I think Model S can do with an 85 kWh battery and a single speed transmission that supports 130 mph,
so a number somewhere in between is 3.8.

Some other relevant threads:
Calculating 0-60 mph time for an electric vehicle
The real top speed of the Model S - Page 2

 

[president_ltd]

The 911 4S and 911 S only differ by 0.1 second in the 0-60. Same engine, with power distributed to 4 wheels instead of 2 wheels, doesn't make much difference.

Why would we expect a substantial improvement in P85 0-60 with the same total power driving 4 wheels instead of 2 wheels when it makes only a very small improvement in the 911 S?

You're making assumptions that (a) its the same size motor, (b) its the same ratio gearing. Its likely Tesla wouldn't materially change the motor (reuse what they already have) but I think its entirely reasonable that they'd use a different fixed-ratio gearbox to provide a different torque/power curve.

Its also possible that they could even do something where they engage/disengage the clutch (neutral) on front/rear at different times to have an 'overdrive' for german autobahn.

Any number of possibilities.

 

[Chris TX]

The Dual motor P85D mule that's running around Fremont does 0-60 in less than 3 seconds. That's with an unrestricted front motor. I have no idea what restrictions will be placed on it for the production unit. It would be nice to be able to have it unrestricted for 20 seconds at a time or so for SCCA or drag racing events. Or for those extreme merging situations. This is the same thing Ford does with their Fiesta ST's "overboost" mapping. It raises the turbo's boost for 20 second intervals when needed. Anything above those 20 seconds and it drops down to normal boost.

 

[RichardC]

The Dual motor P85D mule that's running around Fremont does 0-60 in less than 3 seconds. That's with an unrestricted front motor. I have no idea what restrictions will be placed on it for the production unit. It would be nice to be able to have it unrestricted for 20 seconds at a time or so for SCCA or drag racing events. Or for those extreme merging situations. This is the same thing Ford does with their Fiesta ST's "overboost" mapping. It raises the turbo's boost for 20 second intervals when needed. Anything above those 20 seconds and it drops down to normal boost.

Interesting! Source?

 

[derekt75]

The Dual motor P85D mule that's running around Fremont does 0-60 in less than 3 seconds.

!
I wonder what kind of tires they use and what the road surface is like. Motor torque is irrelevant if your tires are spinning away.

 

[Saghost]

I find no physics fault in Sagshot's "guess", but I would be surprised if it's that good. If it is that good, I'm sure it won't be cheap. but if it is that good, then paying $170k for it would not make you an "idiot". $170k for 3.2s 0-60 is a relative bargain. and a lot of those 3.2s 0-60 cars don't have adaptive cruise control, either.

Point of clarification: it isn't my guess, merely one I quoted from another thread (which I linked.) The original post was from member shawk - not sure if they developed it or found it somewhere.

The physics seem sound, the assumptions mostly reasonable. I'll be interested to see what actually shows up tomorrow.
Walter

 

[mgboyes]

If someone actually paid $170K for an AWD Model S, then yes, they would be an idiot. No way the car is that expensive. Something tells me it won't be more than a $4500 option.

My intention was not to suggest that AWD would add $40k across the board. That would be crazy, of course. I completely agree that the price differential from an S85 to an S85D (with identical performance) should be much less.

My point was that if, with the AWD drivetrain(s) and some additional tuning, they can make an ultra P++ car that does 0-60 in say 3.2s then I believe they could sell that specific AWD derivative, maxed out with all the options, for $170k. Which would mean a healthy profit for them and therefore they should do it.

 

[MartinAustin]

From the stock price thread, where they don't just discuss the stock price:

If Tesla can get to 3.3 seconds they would be the fastest 4 door sedan on road. AFAIK Current title belongs to Audi RS7 at 3.4s.

Audi's own figure on their web site is 3.7 seconds, and I read two reviews (Autoblog and Jalopnik) that both said 3.7 seconds (perhaps they didn't actually get out a stopwatch and test it for themselves).

So Tesla only needs to get to 3.6 seconds to beat that.

While I'm here - calculations based on EPA figures indicate the Audi RS7 uses 2,126Wh/mile in the city, and 1,260Wh/mile on the highway. The P85 appears to average about 350Wh/mile or less depending on driving conditions.

And the Model S has 5 seats and seatbelts; the Audi RS7 only has 4 seatbelts and "2+2 seating." The RS7 has 24.5cu.ft. of cargo space vs. 65.1cu.ft. in the Model S. I could go on...

(Of course, the RS7 has grab handles...)

 

[mgboyes]

And the Model S has 5 seats and seatbelts; the Audi RS7 only has 4 seatbelts and "2+2 seating." The RS7 has 24.5cu.ft. of cargo space vs. 65.1cu.ft. in the Model S. I could go on...

Last time I checked I'm pretty sure my Model S had 7 seats and seatbelts!

Also the Porsche Panamera Turbo S is officially listed at 3.6s (http://www.porsche.com/usa/models/panamera/panamera-turbo-s/) and has done 3.3s in tests (http://media.caranddriver.com/ez/original/application/4bcd27177697b70692257df057ce0f16.pdf)
And the Mercedes E63 AMG S 4Matic lists at 3.5s (E63 AMG Luxury Sedan Sports Car | Mercedes-Benz)

 

[RobStark]

Ahh, but the quote has always been a "comparably equipped" Model S. If there's an AWD Model S, that'd be the one you'd compare with an AWD Model X, wouldn't it?

It seems to me like they could choose and price for AWD they wanted and still meet the promise (though if it's a *large* difference it'd probably get people mad despite technically meeting his promise.)
Walter

Elon has always said single digit percentage premium over Model S not single digit premium over some theoretical higher priced future Model S. That would be pointless.

 

[Gizmotoy]

Edit, summary: 3.9s for RWD, 3.2s for AWD! Tesla: No self-driver, but exotic features and go-fast model

 

[Hawaii J]

3.2 sec, unreal. Called the Dealer to change my order just in time