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Battery Weight V.S. Acceleration Time

Is it safe to assume that there will be a weight difference between the 160, 230, and 300 mile range battery packs? If so, what will this do to the overall acceleration of the car? The website shows that the Model S will hit 60mph in about 5.6 seconds and can have a range of 300 miles. Could this possibly mean that if one were to purchase a Model S with the 160 mile pack that it may accelerate to 60mph closer to or even under the 5.0 second mark due to less weight? Or do you think that Tesla based their approximate acceleration statistic on the lighter battery pack?

Sounds reasonable.

Smaller battery pack equals less available power which unfortunately will more than offset weight loss. The smaller pack with current batteries will not accelerate as quickly.

It will be nice if they based their acceleration approximation on the 160 mile pack in that case. I really hope they didn't base it on the 300 mile pack especially since, from what I understand, that battery won't even be available when they start production.

William13, I don't think you are correct. The smaller pack won't be able to supply the power for as long, but it should be perfectly capable of delivering the same peak power (subject to stuff like overheating). So with less weight, for a short time, it will perform better because of lower weight.

Greg.

Odd, I'm sure I posted here numbers based on assumptions and my post has disappeared.

Short version: estimated weight: 4000lbs, 0-60 5.6secs 160mile pack.

F=ma F is constant m varies by 100kg need to solve a from one side of equation. Result: 230 mile pack around 5.9 secs.

I believe that 5.6 is based on 160 mile version, 230 and 300 mile versions use same amount of cells, different chemistry. Model S battery is probably lighter than Roadster battery thanks to it being part of the structure.

MODERATOR: did my post get deleted for some reason? It should be right after Brian H "Sounds reasonable" -message. If so why? If it never appeared here (can't really remember) I don't know what happened.

Timo;
You probably used one of the secret forbidden number combinations. I can't give you the list because it would probably delete the whole thread, or even the whole forum, of course.

;)
>:p

I thought that in one of the engineering videos that they said with the model s motor that the 160 mile version would not have sufficient amperage to reach maximum acceleration. The model s motor is significantly larger than the roadster motor with corresponding higher power requirement. The 160 mile version has same amount of available battery power as the roadster. I think someone mentioned that the motor could draw more. This would imply the PEM would prevent max acceleration to protect the batteries.

I was kind of hoping for something that could hit 60mph in under 5.0 seconds. ;)

I was kind of hoping for something that could hit 60mph in under 5.0 seconds. ;)

Roadster 3.9 seconds, Roadster Sport 3.7 seconds.

I would love a Roadster! It's quite a bit more than I can afford at this point in time though. I heard 2011 is the last year they will be producing the current Roadster models. I've also heard that they will be bringing back a re-designed model in 2013. That seems like such a short period of time to re-design the car though. Do you guys think it's possible?

According to Tesla's latest Newsletter (28-Feb-2011):

Responding to international demand, Tesla has increased Roadster production by 100 vehicles. In total, 2,500 cars will be produced. Although demand exceeds 2,500 vehicles, Tesla will stay true to its original commitment that the Roadster's limited production will help make it a collector's item. The order increase allows Tesla to respond to market demand in 2011 and 2012 while maintaining exclusivity.

To me, "maintaining exclusivity" and "collector's item" does not sound like they are eager to offer a similar model soon.

Even at 5.6, the Model S is very comparable with the top speedsters in it's class. I'd imagine the sport model would get pretty crazy quick for the class, but it'll be a bit longer before that's available.

According to the article at: http://venturebeat.com/2010/03/29/tesla-extends-roadsters-lifespan-with-... written on May 29, 2010:

After the sedan [Model S] has some time to penetrate the auto market, Tesla plans to bring the Roadster back — with some modifications — by 2013 or 2014.

Is this no longer the case?

ckessel,

A 0-60 mph acceleration time of 5.6 seconds is definitely impressive for a car the size of the Model S. Eventually I'm hoping to test drive and possibly purchase one. My current car can hit 60 mph in about 5.3 seconds, weighs 4465 lbs, can travel about 300 miles per tank of ridiculously over-priced (and always rising) gasoline, and cost me about $30,000 back in 2004. I'm kind of hoping that Tesla will eventually come up with something that's at least a bit faster than my current car that can also travel at least 250 miles on a charge and cost under $60,000. Perhaps the sport version will be something similar? I kind of doubt it will be less than $60,000 though. My car currently has nearly 115,000 miles on it and I've spent a total of about $53,000 on it since I bought it. This cost includes the initial cost of the car, gasoline, repairs, and maintenance.

BladeR;
Lots of those dollars are 7 years old, of course, and are worth rather more in inflated 2011 bux! I'd say you could add $15K or so to that total in current currency. ;)

@Blade

Your total cost of your car is astounding and excellent reasoning to transfer to a EV low maintenance vehicle ... $83,000 in 7 years ... expensive

We are all getting too used to the insane numbers of the Tesla Roadster, and obviously 5.6 looks rather mediocre in this comparison. I would like to put things back into perspective: The Model S is not so bad after all. :-)

A perfectly normal modern family car with comparatively low fuel consumption needs in the order of 9 to 12 seconds to get from 0 to 60 mph. Obviously, the Model S plays in a totally different league.

Premium sedans bring down that number to something like 7 or 8 seconds. These cars have reasonable fuel consumption and are very comparable to the Model S in terms of price, size and "class", but still no match for the Model S when it comes to acceleration.

Then there are high-end performance cars. They are really expensive (much more than the Model S), typically have 6 or 8 cylinders and burn fuel like crazy. Acceleration-wise, those are the cars the Model S compares to and it holds up against them pretty well. The Model S accelerates as fast as a Porsche Panamera S! No surprise some of these cars accelerate even faster, but it takes another order of magnitude (in terms of money and fuel consumption) to keep up with the Roadster.

Here are some figures from the web. I did not even bother to mention the cars that have the greatest volume in terms of sales (the Toyota is just a representative for these models). I focused on the models you probably dream of, and which you want to beat at the stop lights... ;-) Nota bene: Some of them cannot even seat 4 passengers!

Toyota Avensis 2.0: 9.0

BMW
320i: 8.2
335d: 6.0
335i: 5.6
523i: 9.0
535i: 6.0
550i: 5.0
M3: 4.9
M5: 4.7

Mercedes
E 200 CGI: 8.5
E 350 CGI: 6.8
E 500: 5.2
S 350: 7.3
S 450: 5.9
S 500: 5.4
S 600: 4.6

Audi
A4 2.0 TFSI: 7.9
S4: 5.1
A5 3.2 FSI: 6.1
S5: 5.1
A6 2.8 FSI: 7.7
TT 2.0 TFSI: 6.1
TT RS: 4.6
R8 5.2 FSI: 3.9

Porsche
Cayman: 5.8
Cayman S: 5.2
911 Carrera: 4.9
911 GT3: 4.1
911 GT3 RS: 4.0
Panamera: 6.8
Panamera S: 5.6

Aston Martin
V8 Vantage: 4.9
Rapide: 5.2

Tesla
Model S: 5.6
Roadster: 3.9
Roadster Sport: 3.7

One last remark: When the Model S production is up and running and selling well, I fully expect Tesla to bring a sports version of the Model S, comparable to BMW's M-series or Audi's S-series. There is still room for even better performance.

Some wild speculation, that I posted on Traderhood
http://www.traderhood.com/2011/02/19/tesla-er/#comments

We know that the 300mi range battery has the same number of cells (8000) as the 230mi one. Just different chemistry / structure inside cells. So we may assume they also have higher power density, not only energy density. As they can be charged in 45 min. to 80% capacity, all models should be quite high power both ways. The 5000 cells battery can achieve 0-60mph in 5.6s.

So where I want to come to is the following : the 300mi pack should have about twice the power (and energy) than the 160mi one. Add a second motor for AWD and you get a sport version with double the power and torque. It is slightly heavier (100-150 kg) so instead of 5.6s/2 = 2.8s, you get 3s for 0-60mph !

I know it sounds crazy, but for $10k-$15k extra for the end user, you get a family car that beats all Ferraris, Lamborghinis, Porches, Jaguars … you name it ! You can count on your fingers the cars getting under 3s for 0-60mph, we are talking about real super car beasts here !

Of course they could not sell Roadsters anymore if they announce this Big Boy. But they plan to stop production this year and sell the stock by the introduction of the Model S anyway !

So I guess we have to wait at least one year to check how far from the truth I am. Of course, if the sports model does not have two motors, just a slightly modified one, none of this is even close.

I would add that they also have hinted at an AWD, and it makes no sense to build a complicated transmission which would be as heavy as a second motor (and a bit of extra cables + software) – and inefficient. As the battery occupies the floor of the car, the transmission would also modify the chassis. And there is a trunk in front, just use a quarter of it for the second motor (+ PEM + the small gearbox).

45 minutes to 80% of 100kWh battery pack is only 106kW, and I believe 100kWh is overestimate of battery size. Both Roadster and Model S engines can draw over 200kW. Considering that is already twice the capacity it is quite good power density. Putting in second engine probably can't get double power from same package.

Fun idea, albeit your calculation is a little naive. Acceleration does not go linear with Power:

318i / 105 kW / 9.1 sec
335i / 225 kW / 5.6 sec
M3 / 309 kW / 4.9 sec

523i / 150 kW / 7.9 sec
535i / 225 kW / 6.0 sec
550i / 300 kW / 5.0 sec

911 Carrera / 254 kW / 4.9 sec
911 GT3 RS / 331 kW / 4.0 sec

You see what I mean? If the relation was linear, the 335i would jump to 60 mph in 4.6 seconds, based on the 318i data, and the 550i would be a 4.0 rather than 5.0 based on the 523i.

So yes, it is probably possible to accelerate the Model S a lot faster than the first version will be able to go, and going AWD probably helps not only to get the required traction, but also by adding up the power of two motors. But I doubt that a car the size of the Model S will accelerate in 4 seconds or less for any reasonable amount of money.

it's double power, double torque, double traction (wheels to ground) :)
and a bit of extra weight; also there is enough weight on front wheels to get good traction from the battery and extra motor

and yes, the charging time was probably a bad example, but usually power in is much lower than power out; maybe the better way to compute is 8k cells instead of 5k cells + better chemistry

oh, and there's no stupid gearbox to lose time changing gears (+ lost efficiency) and tight RPM windows where you get maximum power and torque

in the ideal situation, double force for the same amount of mass means double acceleration which is half the time to accelerate to the same speed (speed is the integral of acceleration and the integral operator is linear :p )

so I speculate that double torque, double power and double traction (from 0 RPM with no gear changes) amounts to about double the force exerted on the car - of course the main question is the battery and there are several other minor questions (e.g. does momentum reduce the traction on front wheels ? if so, by how much ? etc.)

http://www.greencarcongress.com/2009/12/panasonic-20091225.html

It seems not to be big difference in weight of 230 mi and 300 mi batteries compared to 160 version (current)if number of cells is the same. +20 % is safe assumption between the last two.

46g-44g = 2g seems more like 5% :) - but of course one should also add at least 150kg for the extra 3k cells
so you get a car that is about 15% heavier; so in an ideal world you get 3.2s 0-60mph time - no other family car could ever dream to approach this !

I'm assuming that they use 3.4Ah in the 300mi pack - anyway, we have no info about that, the cell design might have changed by now

in the ideal situation, double force for the same amount of mass means double acceleration which is half the time to accelerate to the same speed

Right. In the ideal situation, there is also no air or tire resistance, and infinite traction. Well... infinite traction is probably hard to achieve with zero tire resistance, and I am not sure if I would consider a world without air "ideal". ;-)

There is no way Tesla is going to make a Model S 0-60mph time around 3 seconds.

Not only is the power v.s time not linear, a car with that capability would scare most drivers. This is a no go from a safety standpoint for a family sedan.

scared drivers will choose the "normal" Model S :)

Not only is the power v.s time not linear, a car with that capability would scare most drivers. This is a no go from a safety standpoint for a family sedan.

They could use a special Top Acceleration Key, as is used for the Bugatti Veyron to unlock it's top speed ($2.7 Mio, 2.5 sec 0-62 mph, 883 kW, 430 kmh/267 mph top speed). ;-)

msiano17,

I haven't paid $83,000 for my current car overall. I've paid $53,000 which includes the initial cost. Here's a bit of a break down:

Initial Cost: $30,000 in 2004
Starter replacement at about 80,000 miles: $700
Water pump replacement at about 85,000 miles: $300
Radiator replacement at about 95,000 miles: $200
Clutch replacement at 100,000 miles: $2,300
Oil changes over 6 1/2 years (synthetic): $1,820
Gasoline over 115,000 miles (average 20mpg, $3/gallon): $17,250

This comes out to $52,570 which I rounded up to $53,000 for miscellaneous things that I'm sure I've overlooked. Do you guys see anything that I may have missed?

I also have a hard time thinking that Tesla will produce a Model S that is capable of super car acceleration times. It would be awesome if the released one that could compete with the Subaru STI and similar cars though I wouldn't consider cars like that in the family class.


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