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Battery Weight V.S. Acceleration Time

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?

qwk | March 9, 2011

Hp is efficiency over a certain amount of time.

All the torque in the world will not help you win drag races if you don't have much hp. That being said, vehicles with more torque are much funner to drive, and feel faster on the butt dyno, than a lower torque vehicle with much more hp.

rj | March 9, 2011

I'm not an engineer, but it seems that you'd want all battery options to have the car handle the same, so all adjustments on the assembly line would be the same for suspension and motor, etc.

This would lead me to keep the battery pack weights the same. So simply adding ballast to adjust each pack option so all weigh the same would seem reasonable.

If this is true, then acceleration and handling would be about the same for all battery pack options, assuming the same voltage and current delivery for each option.

Timo | March 9, 2011

qwk, HP is derived from torque. Without torque you wont have HP either. Those are interchangeable values.

What matters most in drag race is RPM range where you get that torque. That gives you speed. The higher the RPM range the higher is the speed you can still accelerate. In ICE cars that is very clear because they need to use transmission to keep the car in max torque area for accelerations.

In EV it is a bit different matter, there is no transmission to keep your car in max torque area. You just start to accelerate from zero RPM and stop accelerating when you car torque matches friction forces. There too wider RPM range helps, but engine HP doesn't really tell you anything about acceleration because your max acceleration actually starts to drop before you reach the max HP.

Instantaneous torque or hp doesn't really tell you anything, you need to combine RPM range to it in order to get a clear picture what the car capabilities are.

qwk | March 16, 2011

Timo,

I know that hp is derived from torque. The lines always cross at 5252rpm. Like I said before, hp is how efficiently you produce work at a certain rpm.

The reason that ICE cars need high rpm's is that they are the most efficient at coverting fossil fuel energy to work at higher rpm's.

You cannot and will not win drag races with low hp and high torque. Simple physics.

Straight Shooter | March 18, 2011

The Model S is not going to turn itself into a Ferrari killer. Lets get that out of the way. If you want to blow the doors off a $500k car or a $2m super car, then you have some wiating to do, and the Model S will NEVER be that car.

The Roadster might get into the low 3 second range, but we talking about Version 3.5 or 4 or higher. Why? Because of this little thing called "The Law of Diminishing Return".

This law states that if spend twice the money, you won't get twice the value. As an exmaple, a $200k car is not twice a good or fast as a $100k car. A $200 blue ray player is not 1/2 as good as $400 blue ray player and in fact only 1 in 1000 would be able to tell the difference in picute quality.

Lets use a real world exmaple, as a chunk of you guys are focused on accelleration and nothing speaks bigger volumnes than drag racing. About 5-10yrs ago the fastest drag racers , top fueler nitromethane drag racers, were doing the quarter mile in 5 seconds and developed almost 3000 horespower from a single V8 engine. Pretty impressive stuff. Today the record is 4.4seconds, but it takes almost 8000 horsepower to get there.

ANY Telsa improvements, like shaving off 1 second in the 0-60, is the stuff of dreams. The best speed freaks in the world took 10yrs to shave off 0.6seconds and it took almost 3x the HP and probably cost well over $50 billion

Nicu | March 18, 2011

It is indeed very tempting (and the easy way too) to generalize facts to principles ... like saying "a machine heavier than air cannot fly", "the world is flat", "the universe is infinite" and people much smarter than both of us to power 2 have made this error. Einstein's work was regarded as total failure in the beginnings, just because Newton's principles served us so well for centuries ... they had to be right !

I am talking about your examples with dragsters : they are the extreme edge of an exhausted (pun intended) technology, it is just natural that every improvement comes with very high price, after a long sustained effort.

Just take a look at the Roadster, which is the first version of a new tech, an almost artisanal product by a beginner manufacturer. It is faster (up to some speed) than many much more expensive cars on the road that needed a century of evolution to get where they are today.

You give examples of DVD players ... what about the iPad 2 which is 2x CPU / 9x GPU faster than iPad but only $100 (20%) more expensive (after price cut) ? How is this possible when one year ago it was the pinnacle of mobile tech ? Human intelligence plus hard work plus the right tools / tech can make wonders !

I am not betting on this, I just say it is achievable ! They are surely much better than any of us assessing the need for such a product (family super-sports car ? sounds a bit fishy !) and the effort / money needed to achieve that.

What I bet on (with some $25k invested in TSLA, about half in shares and the other in call options) is that they will deliver a great car in Model S, no price increases and no major delays. Basically, if everything goes well, the profit on those will pay the Model S of my choice in about 2 years time !

Leofingal | March 18, 2011

In response to the last couple posts, I think that more likely than Tesla making such a supercar, or toward straightshooter, perhaps an approved aftermarket modifier (think Shelby/Ford) may offer some sort of souped up version of the S. I can imagine that with an upgraded rear axle, and reconfiguration of the battery you could probably shave off a second or two (just look at the Roadster). I am not sure that doing this themselves is really beneficial to Tesla for many years (unless it is partly to amuse the engineers!) as they should be working on going in the direction of the higher volume options.

jfeister | March 18, 2011

A number of poster's have stated that the 230 and 300 mile options will have different battery chemistries. That doesn't make a lot of sense to me for several reasons:

1. The cost difference between the 160 to 230 is the same as between the 230 and 300.

2. Economies of scale are less effective if you make multiple configurations.

3. The supporting electronics might need to be different, further eliminating commonality and increasing cost of production.

Can anyone post a link referring to different chemistries between ranges?

Given that it's rather unlikely there is any chemistry difference, I would suspect that the 300 mile option would weigh more and would be slower. Tesla consistently leaves out caveats when talking vehicle specs so I suspect it will be lower than the 5.6 number usually given.

If anyone can prove otherwise I'd be interested.

Nicu | March 19, 2011

Very old info, but they are not changing their design every few months either
http://www.greentechmedia.com/articles/read/panasonic-set-to-make-batter...

Of course the electronics will adapt to cells, half of their work on it is software. They are building a platform for the future, not carving each model in stone ! That is the difference to the industry of dinosaur juice burners.

Volker.Berlin | March 19, 2011

@Straight Shooter, not scientifically precise in every respect, but very well said IMO.

Volker.Berlin | March 19, 2011

@jfeister:

1. The cost difference between the 160 to 230 is the same as between the 230 and 300.

You must not confuse cost with price. What you mean is price, and that is primarily market driven, not necessarily reflecting actual cost.

2. Economies of scale are less effective if you make multiple configurations.

That's true, but if you just keep adding cells of the same kind, the car grows heavier and heavier which does not help with range either. At some point, most of the juice you store in the battery is needed to carry the battery itself... OTOH, a different, more capable battery chemistry may be much more expensive than the simpler one, so up to a certain point the simpler and cheaper technology makes more sense. Customers will only shell out the extra required for the more advanced tech if they are getting something extra in return which they cannot get otherwise. Like an electric car that runs 300 miles at a time.

3. The supporting electronics might need to be different, further eliminating commonality and increasing cost of production.

That may or may not be the case. If it is, just add that to the "economies of scale" clause above and the same argument holds.

jfeister | March 19, 2011

@ Volker

- If I ask how much the car costs would you quote the cost of production? Of course not. So the term is obviously dependent on who it's being applied to. Cost to the consumer is usually based off the cost of production, so it's an indicator.

- The idea that a battery is at some point not worth the range hit due to it's weight makes no sense. If that were true it wouldn't be worth adding the first cell. Think conservation of energy. Total battery weight does reach a limit when it comes to deliverable torque due to limits of the electronics and motor, but not range. If anything the ratio gets better since the cross-sectional area of the car remains the same, meaning more total energy with the same aerodynamic resistance.

There is only 1 reason you'd want to use a different chemistry: It's not worth putting the better chemistry into the 160 mile version because the resulting margins are less than the costs accrued from loosing commonality in design. In my experience, commonality is worth a lot, not only because of economies of scale, but because it means less inventory management, simpler support structure, less engineering to release, less testing, and on and on. But who knows, maybe it's worth it.

William13 | March 20, 2011

I don't know what batteries will be used but the prior engineering talks indicated that the 160 and 230 would use the same cells. They indicated fewer cells being used in the 160. They indicated a different cell for the 300 mile version. A $1.00 difference in the price of the new cells adds up to $8,000. This is well worth having two different inventories.

jfeister | March 21, 2011

And a $0.01 difference and up to $80. If you don't know the input the output is pretty useless.

msiano17 | March 21, 2011

This thread has touch on a lot of topics for the battery... just wanted to clarify that the 0-60 in 5.6 seconds was probably the time for the 160 pack whereas the 300 will be over 6 seconds?

Meaning that if you get the 160 pack you have a quicker car? Seems backwards compared to the usual thinking, but then again it is not an ICE so new concepts are needed.

Timo | March 21, 2011

You probably get that 5.6 with 230 and 300 mile packs, I believe that 160 mile pack doesn't give enough power for faster time even with lesser weight of the pack. Weight difference is also pretty small between 160 and 230 mile packs, pack structure in both is same, so it is basically just less cells and connectors for 160 pack.

8000/230=x/160 = 5565 cells = 250kg vs 360kg = 110kg difference. Maybe 150kg at most. In 1800+kg car that is less than 10%.

So even with that 5.6 being 160mile pack and it gives full power you still have less than 6 sec time for bigger packs.

t7n7 | March 22, 2011

How is 150kg small? That's the weight of 2 passengers.... Do you have any idea what a big difference that makes under acceleration?

My X6 is one of the heaviest vehicles on the road and even a 150kg savings will result in .1 - .2 from the 0-60 time. It does 0-60 in 4.7 seconds right now. I'm sure the tesla will be around 5.6 as advertised.

Dunno how but I can't see them marketing 0-60 in 5.6 and 300mile range in the same sentence if it cannot be done.

Timo | March 22, 2011

F=ma == m1a1=m2a2, F is constant, m1,m2,a1 are known need to solve a2.

a2=m1a1/m2

60mph in 5.6 sec = 26.67/5.6 = 4.7619m/s^2 (nearly half a g BTW)

a2 = 1800kg*4.7619m/s^2/ 1650kg
a2 = 5.1948m/s^2

60mph in 5.1 secs

Or other way around 1650kg - 1800kg 0-60mph 6.1 secs.

Seem to be over 6 secs, but only by 0.1...assuming that my guess about 150kg is correct.

Anyway these are pure speculations, we don't know the real car weight, weight differences between packs, which package gives that promised 5.6 secs, can small pack deliver same power, do they use same engine etc. etc. etc.

VolkerP | March 22, 2011

@t7n7 it is common marketing strategy to quote features in one paragraph that are not available as a combination in one car but only in different versions of it. Usually the best performance values are cited along with the "entrance level" values for price, running costs, energy usage, and so on. Sometimes you get a VW beetle "starting at" US$900, top speed "up to" 160mph, 40mpg, insurance cost "as low as" 30 bucks per year yada yada. Everyone reading this stuff and taking it for granted is just gullible.

I have the impression that TESLA is trying to be fair, but for sure they are not hiding what they are going for.

qwk | March 22, 2011

I bet that Tesla will limit the bigger packs with firmware, so that all the cars will be around 5.6s.

Then they will offer a Sport version for extra $$ and it will have around a 4.4s 0-60 time.

Tim10 | March 22, 2011

A recent article on the alpha build tour mentioned the motor in the Model S being 300kw. If true, then as mentioned it is unlikley that the 160mi pack could provide full power, 300kw, as that would be ~6C. Given the pack is lighter it propbably helps make up the difference.

William13 | March 22, 2011

Not to be argumentative but the small pack might give max acceleration only if it can supply the entire 300 watts for the motor. This is no small feat and even if one were able to do this it would much more quickly degrade the battery life. Thus I suspect that firmware will limit the acceleration of the 160 pack. If it is not limited by Tesla the batteries will go bad very quickly for the extreme Jack rabbits. I expect to use maximal acceleration 0 to 60 fewer than ten times in this car. Max acceleration 0 to 30 is another thing and would also degrade the smaller pack if not controlled by firmware.

Timo | March 22, 2011

BTW, looked at the FAQ and it now states that 5.6sec acceleration is 0-100km/h not 0-60mph. 60mph is about 96km/h. That means it's a bit faster than that.

300kW is huge, it's almost 30% higher than Roadster engine, and weight is only about 20-25% heavier. With top speed at 200km/h that probably means that Model S actually competes Roadster in higher speed accelerations (higher kW with same torque means higher RPM for top torque). This is from autobloggreen "kicking out around 295 pound-feet of torque and 300 kW". Roadster Sport engine gives 295 lb-ft torque.

Uh, I want one, but can't use one.

Tesla, hurry up with your next models...

Make something like Mitsubishi EVO with twin engines and beat everybody in World Rally Championship.

Volker.Berlin | March 25, 2011

I just had to add the Fisker Karma to the list. It makes Tesla look so good... :-)

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
AMG E63: 4.5
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

Fisker
Karma, EV mode: 7.9
Karma, parallel hybrid mode: 5.9

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

Volker.Berlin | March 25, 2011

Fisker
Karma, EV mode: 7.9
Karma, parallel hybrid mode: 5.9

I have to correct myself here: The Fisker Karma is a serial hybrid. Still, it appears that "Sport" mode cannot be engaged without the ICE running. I know this is not a Fisker forum, but does anyone care enough to explain that to me -- how the electric motor becomes so much stronger when there is an ICE running on the opposite side of the battery, without any mechanical connection to the driven axle (the ICE, that is)? Seems that the battery would capitulate in an instant when the "Sport" mode soaks serious power, so the ICE has to provide power at approximately the same rate, and the battery becomes theoretically irrelevant in this scenario?

Timo | March 25, 2011

There is probably some direct connection from ICE-powered generator to the electric engine with just some control electronics in a way.

William13 | March 25, 2011

The websites say that the Fiskar batteries will not supply enough power for the sport mode. The pem is protecting the small battery pack from harm. The engine makes electricity which is sent to the motor. Theimplication was a generator separate from the motor. No direct connection a la Volt.

Nicu | April 24, 2011

for those who still don't get this new tech, go to 3:38 in this interview with E. Musk
http://online.wsj.com/public/page/0_0_WP_3001.html?currentPlayingLocatio...{CCF1FC62-BB0D-4561-938C-DF0DEFAD15BA}

quoting approximatively : a sports version of the Model S will have acceleration times comparable with those of the Roadster, and in any case, it will be the fastest sedan on the road

Timo | April 24, 2011

He said "performance version". Anyway with 300kW engine instead of Roadsters 215kW and weight difference less than 2/3 it should have, if not higher acceleration, higher top speed, especially with better aerodynamics.

It might be quite competitive to Roadster on drag-race even without any performance version, because Roadster hits the RPM point of diminishing returns way before 60mph and it had with its 12.6+ second quartermile with top speed at about 102. (http://www.nedra.com/record_holders.html) Model S might actually get it to 120mph top speed with better mid-stage acceleration.

Model S might be faster in highway speed passing than Roadster. It should be quite a rocket in four wheels. If they make performance version with initial acceleration as fast as Roadster, then we might have Roadster killer there. Faster, more practical, more luxurious and cheaper than Roadster. Who would then choose Roadster over it?

For that reason I don't believe they make that performance version before current Roadster manufacturing stops. Then it is time to make Tesla-designed Roadster in their own factory that is in all possible ways better than current Lotus-derived model.

Lush1 | April 27, 2011

So much for range anxiety! Are you guys shooting for Jeremy Clarkson like performance? Doesn't the Tesla's software employ a sort of "launch control" which tailors how the power gets to the wheels so they don't break loose and produce a lot of smokey wheel spin? It seems to me that they could keep all models pretty close to the same acceleration curve by tweaking a few parameters, assuming that the 160 pack has the power to do 5.6 sec. Maybe the bigger packs could be faster if they varied the curve. Like everybody in this thread, I'm just speculating, but it seems to me that if all that power and torque went unabated to the wheels when you mashed the throttle, the wheels wouldn't hook up very well. Isn't the Model S going to be shod with low resistance tires to increase range. It would probably need different shoes to get the power to the pavement better, like slicks!
Don't get me wrong, I like going fast (occasionally, for fun or to merge with fast traffic) but a luxury sedan doesn't strike me as the ideal vehicle for 3-4 second 0 to 60 times. Is there any such thing in the ICE world? The Lexus LS hybrid has a 5 liter, 300hp engine and an electric motor which combine to deliver 438hp and does 0-60 in 5.5 sec. The MB CLS 550 does it in 5.4 with it's 382hp/391lb/ft engine. AMG offers the C63 with a 6.3L lump that will get you to 60 in 4.4 sec, but now were getting into specialty cars with their accompanying rapacious thirst. I'll be happy with the current Model S acceleration spec, which is on par with my CLK 500. I feel guilty every time I drive my thirsty Benz ever since I drank the Kool-Aid and embraced green wheels over the madness of muscle cars. I'm not and aggressive maniac on the streets but, I confess, my driving habits are more assertive than most people I know so I would surmise that most Tesla buyers will find it quite peppy. While EV's are much more eco-friendly than gas guzzlers, if we're charging from the grid, we still leave a carbon footprint. Making Teslas capable of 3-4 second times seems contrary to one of the primary reasons for driving them. The speed is seductive, but not really wise. I hope Tesla toys with testing the upper limits of speed, perhaps building electric race cars but, as tempting as it is, I really hope they don't start selling supercars, especially not at the outset when demonstrating range and environmentally friendly traits are such important factors for convincing people that EV's are credible, practical, responsible vehicles. Blowing the doors off of obscene, fuel wasting ICE monsters doesn't send that message. Sorry to be a wet blanket but I feel that driving a Model S carries some responsibility. Besides, when people call the cops to report some maniac driver in a Tesla going like a bat out of hell, it won't be hard for the law to find the right car when it's the only Tesla withing hundreds of miles, (except perhaps in LA). We can't be inconspicuous like somebody driving ubiquitous cars like black Mercedes.

Timo | April 27, 2011

@Lush1, Tesla is not making "environmental friendly" as main selling point. They are making electric vehicle that just beats crap out of ICE competition, and that will be their main selling point. Building a real EV supercar would be great selling point, especially if they manage to make it (relatively) cheap. Then at the last comment they might add "and BTW, it is about as green as cars can get".

As contradictory it might sound, in EV-world bigger is more efficient. Bigger engines give bigger power, but also bigger range by better efficiency. This is opposite to ICE cars where bigger engine usually means poor mpg.

I compliment Tesla for going in "non-green" way of proving EV:s practicality. Green is not very good selling point, you might get some people buying your car by making car-like golf-carts and telling that they are really green, but majority of car-enthusiasts will look for performance, maintenance costs, practicality and looks before any other considerations. For all those four points Tesla Model S is excellent.

If you get a common environmentally ignorant thug to buy a EV just because it is cool, then your task is done.

Vawlkus | April 27, 2011

Or if he wants to smoke his buddy at the lights, blowing the doors off that friends overpriced ICEd smog machine.
Remember, EV cars still have the 'crappy performance' label sewn on them by the ignorant. People need to be made aware of what EVs can actually do these days.

Lush1 | April 27, 2011

Timo, Tesla is ABSOLUTELY making "environmentally friendly" a main selling point (but by no means the only selling point). But don't take my word for it. Go to this page of the Tesla website: http://www.teslamotors.com/goelectric
I highly recommend reading that portion of the Tesla site so you will realize that you will be driving a really fast car that has a small carbon footprint and is produced by people dedicated to improving the planet by building and selling their cars. Just click the "Go Electric" tab. The biggest thing on the first page is a blurb that says:

"The overarching purpose of Tesla, and my reason for personally funding the company, is to expedite the move from a mine-and-burn hydrocarbon economy towards a sustainable, solar electric economy."
Elon Musk

Him, I believe.

Tesla has been very vocal about their efforts to be as green as possible in their manufacturing processes and have gotten a lot of publicity as a result. Yes, they are making cars that beat the crap out of the ICE competition. They probably would never have gotten off the ground if they tried to sell some anemic, short-range, ugly, small EV. That said, there is no shortage of buyers for cars like the Prius. Nothing against it, but I'm sure neither of us is interested in a cramped hybrid that takes over 13 seconds to crawl it's way to 60mph. Teslas outclass virtually everything. They certainly do promote performance, quality and luxury. Those are great selling points and might even convince people with no green awareness to buy them, which is great. But how fast do MOST people want a luxury sedan to go; 0-60 under 2 sec, Mach 1? I hope to see Tesla grow exponentially, eventually becoming the worlds biggest car manufacturer; offering vans, SUVs, compacts, buses, pickups, super cars, sports cars; in fact, anything with wheels. For now, I hope that they keep their focus tight and offer great cars with reasonably great performance and features. Cars that make sense to the general public, not just speed freaks.
Personally, I'm excited about the reduced carbon footprint I'll be leaving. I hope to power (partially or completely) my Model S from a planned solar array on my home. The money I'll save versus gas is a big plus too. I only drive about 6000 miles per year. I'm paying $4.50/gallon and getting about 15mpg in my Benz. I can afford it, but it sickens me to use so much petroleum. I haven't calculated it carefully but using numbers posted on these forums, I roughly estimate those same 6000 miles will cost me about $125/year in electricity. That's a whole other kind of green that makes sense for every car owner.

msiano17 | April 28, 2011

@Lush1

You do have a valid point in that they are going for a "Green selling point" BUT I think it is up to interpretation to be honest.

For instance, reading the quote you just posted from Elon. I do not jump at the thought that he wants to go green. Instead I take it that he wants to help abolish our dependency on fossil fuels... with the benefit of going green also.

So I am not totally disagreeing, I do believe they are having it be a "green car" is a part of their selling point, but I think it is a couple down the list.

The Model S:

starting at 50k, luxurious, spacious, cutting edge technology inside and out, high performance, matching or beating any car in its class .... and it is alllll electric saving you hundreds a month at the pump. Its as green as you can get without sacrificing a thing.

Sheesh they could turn that into a commercial even ha. Yet, I see it in that fashion as their selling points.

t7n7 | April 30, 2011

I agree with Timo. Less than 1% will buy a Tesla to help the "environment"

I think what Elon meant was..... He doesn't want to depend on fossil fuels and wants to go a route that is SUSTAINABLE.

Gas prices right now pretty much explains it.

People want performance. That will NEVER change. Be it cars, motorcycles, atvs, jets or even trucks.

Supergreekster | May 12, 2011

I don't think this acceleration vs. battery choice is something that can be known until alpha/beta vehicle tests are done with all of the battery packs...

The theoretical acceleration means nothing if the car doesn't achieve it in the real world...

Real world acceleration is the only thing that matters...

msiano17 | May 15, 2011

I am not great with the calculations like some of you here but this topic has been in the back of my mind for a while and I did come to one conclusion ... our basic assumptions are incorrect in the first place because we are so accustomed to how ICE's work.... "Want more Power? Get a huge V12 twin-turbo engine!"

With an EV .. the amount of range in the battery pack just seems to represent the amount of energy storage capabilities for the car. For instances, the 160 and 300 range models have the exact same motor and gear assembly unit that connects to the battery and rear wheels. So I do not see how the 160 wont have as much acceleration as the 300. The only drawback of pushing the 160 that hard is you wont have as much energy left afterwards to get to next destination like the 300.

Maybe I am missing something the math and physics of it all, but just logically speaking, the motor is the same therefore acceleration should be also.

Timo | May 15, 2011

So I do not see how the 160 wont have as much acceleration as the 300.

Problem is power density, which is quite limited in these Panasonic batteries. Drawing out 300kW from 45kWh battery requires quite good power density. From bigger battery it is not a problem, but for small battery you might need different battery chemistry.

msiano17 | May 15, 2011

So even still it seems to still be possible, just more difficult for a smaller battery.

Plus the weight reduction should help assist... again logically it seems to make sense to be the same, but the physics could say otherwise. I guess we will have to wait til the press conference from Hanz and hope he has some answers.

William13 | May 16, 2011

Think in terms of volts and amps. All the packs will have the same voltage available to run the motor. At the high end of power usage the smaller packs may not have enough amps or be limited by the PEM from drawing a higher amperage. The higher the draw the more risk of damage to the batteries. We lay people don't know where that limit would be reached. We know that it can fast charge from 20 to 80% capacity in 45 minutes but that is much slower than the potential 300 kw draw.
Assume 100 kWh battery going from 20-80% in 45 minutes. 60kWh/.75h=80kW. Thus we know that the 100 kWh batteries are safe with 80kW going in or out. The same calculation with a 50kWh pack leads to only 40kW. This assumes the same chemistry for the batteries.
Remember the people who had their computers burn their laps? This was from waste heat from the batteries discharging. The same heat generation occurs in a Tesla.

Timo | May 16, 2011

I otherwise agree, but: Remember the people who had their computers burn their laps? This was from waste heat from the batteries discharging. I think that was from electronics getting really hot, not the battery. Some of those processors get really hot when they are pushed to the limit. You could (quite literally) cook eggs with them.

That also is the reason why laptop batteries do not last very long. Batteries in them need to endure way too high temperatures.

Vawlkus | May 17, 2011

It was more the constant overcharging Timo. People always had their laptops plugged in, so the battery was always being charged, even when it was full.

Timo | May 17, 2011

That also is [insert "one"] reason why...

BladeRunnings | June 2, 2011

Thank you for all of your replies! I think I'm going to hold out and see if they release a sport version of the S in a few years. Hopefully my current vehicle will hold up until then.

Volker.Berlin | December 21, 2011

Here we have it: Juice tops weight.

40 kWh / 160 mi / 6.5 sec / 110 mph
60 kWh / 230 mi / 5.9 sec / 120 mph
85 kWh / 300 mi / 5.6 sec / 125 mph

Performance version:
85 kWh / 300 mi / 4.4 sec / 130 mph

Volker.Berlin | December 21, 2011

As energy storage capacity increases, so does the total power. This results in quicker acceleration.

From the updated "Facts" page:
http://www.teslamotors.com/models/facts

Erik M. | December 21, 2011

Can somebody explain why you get better acceleration and top speed with the battery options? My laptop doesn't perform faster with a larger battery...

brianman | December 21, 2011

Can somebody explain why you get better acceleration and top speed with the battery options? My laptop doesn't perform faster with a larger battery...

Mine does. When the larger "battery" is the wall outlet. Because I change the brightness and so forth for different plugged in (performance) and battery behavior (stamina).

A better comparison might be 2-channel vs. 3-channel vs. 4-channel memory, though.

stevewen1 | December 21, 2011

Any of you electrical geniuses think that there will be an aftermarket software tune to boost the 160 and 230 to do 4.4sec 0-60? or is the performance capped?

Volker.Berlin | December 21, 2011

If you boost it by software you will fry the the PEM, in case of the 85 kWh battery. In case of the smaller batteries, you will fry the entire battery.

The larger battery is required to safely provide the power (think "max power per cell" is constant, 85 kWh pack has more cells -- not entirely accurate but a useful rule of thumb) and the performance version will have a heavier inverter that can safely handle the power.

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