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0-60mph in less than 4sec Tesla Model S

40 kWh - 6.5sec
60 kWh - 5.9sec
85 kWh - 5.6sec
Performance 85kWh - 4.4sec

100kWh - ???

So with the performance version they allow more peak wattage to the motor to allow for greater burst of acceleration. And with increased kWh battery pack you see better speed performance.

So in the future... If I upgrade my battery pack, to the newer 100+ kWh battery pack, could my "old Model S" see a new performance boost? I'm not sure how this all works out, but could be a huge perk to owner that keep their car in good shape and upgrade the battery pack down the road if Tesla build ones that can be swapped out!

Any thoughts?

With a car weighting near 4000lbs getting anything better than 4.4 0-60mph would be very hard, it no longer depends of power but traction. You would need special tires made for drag racing to (clearly) beat that. You might get tiny bit better times, but not much.

You would see a bigger effect in higher speeds with longer gear ratios. Both top speed and high speed acceleration get better.

I was just this morning wondering if just battery replacement allows better acceleration, or do you need new PEM and motor too. If you do need new PEM and motor, are they directly changeable or do you need to do things in brakes, suspension etc. too? If they are changeable, how much would it cost to change the whole drivetrain package?

What about using AWD and two motors like the Model X? What would that have to say for the acceleration?

@wstrask4

My expectation is that they have exactly 2 sets of wiring (and electronics) -- Performance and not. It's quite possible that I'm totally wrong and they have 4 flavors. But let's go with 2 for now...

If they have 2, I would expect that you can later replace the 40, 60, or 85 non-Performance original battery with a newer size battery but that you will still be gated to weaker (higher 0-60 time) than the original 85 Performance edition.

Will you have the option to later upgrade the wiring (and electronics) when getting a stronger battery at that point? No idea, but it's interesting to think about.

Ok, I've laid out a theory. Forum experts can now guide you closer to the reality. Grab some popcorn. ;)

Low center of gravity and 4WD helps, but not twice as much as single rear engine for that initial acceleration. Rear tires get the main part of the acceleration simply because they lift the weight off the front end. (simply turning wheels tries to tilt the front up.)

@Timo - if the center of gravity is above the axles then accelerating lifts the front end. The lower the center of gravity, the lesser the effect. Theoretically, with a very heavy battery pack below the axles, accelerating could lift the rear, but I don't think that the S and X platforms are quite that bottom heavy. Still, I'd expect the front tires to be much more useful on an X than they are on the typical AWD Audi and SUV...

flar - Say what? Acceleration lifting the rear on a rear drive car?

Same discussion as the low Cg affecting the sway in turns. There is a separate thread on this, but I believe that what flar said is true, the front should not unload as much as on a typical vehicle due to the weight distribution and lower Cg. Interesting...

@flar - The distance between the application of torgue, the percentage that is perpendicular to gravity and the center of gravity is what determines the force necessary to twist a RWD car. Think of a simple experiment where a weight is on the end of a yard stick. With you holding it at the top with the weight hanging down, it takes very little torque to move it slightly. Now try to hold that weight perpendicular and you will see the large increase in torque necessary to hold it there. Now back to your car example. It is the combination of the amount of that center of mass and how far forward of the rear wheels that will determine the torque necessary to lift the front end. The vertical portion of the center of gravity has little to do with the issue, nor does the COG moving from left to right. It is all about the how far forward the COG is. It is also not theoretically possible to lift the rear end if the torque is applied in a RWD car going forward.

+1 BruceR... just think of how the forces are being applied.

Back to the original question.
@wtrask4 - Don't confuse power and energy. These terms represent very different, but related concepts.

Power is the RATE at which energy is transferred , expressed in watts or kilowatts.

Energy is the AMOUNT of power consumed, expressed in watt-hours or kilowatt-hours (kWh).

So TESLA is selling us a battery pack rated in Energy, not power. What is confusing people is that a higher energy pack can safely deliver more power without damaging itself. What they have done is program the electronics to limit the power to match the safe power level that a particular energy pack can withstand. In the case of the performance version they are also installing a higher power motor/controller arrangement. (Have not seen exact specs of what all they changed yet.)

So, will your power go up it you increase the energy storage? Absolutely not. Can your controller be programmed to have higher power? Possible, but only up to it's current maximum ratings.

@BruceR: for a given battery chemistry, you're right. Different battery chemistries can, however, allow for higher discharge and/or charging rates relative to the battery's energy.

True Robert. I didn't want to complicate the discussion further by ponting out that the 85kWmh pack is alo a slightly different chemistry than the 40 and 60 packs and may haver higher C rate capabilities also.

Bruce R;
Hm; consider flar's assumption. If the COG is below the axles, the car would tend to rotate nose-down with force applied from the rear axle only. That's how the vectors look to me.

I would gladly accept 0-60 in 9 seconds to get appreciable additional range (50 miles). I will use the additional range much more often than a large acceleration.

The torque component from forward acceleration is the force at the wheel patch times the vertical distance from the CG to the wheel patch (not axel center to CG). That torque that tends to lift the front end in forward acceleration, is always positive unless the CG is lower than the road surface.

A lower CG reduces the front end lifting effect, but unless the CG is below the road surface, there is always some lifting of the front end in forward acceleration.

OTOH there is also a inertial mass component trying to go down in acceleration if COG is below axle and that presses car down (note: not same as lifting the rear up). Might be a bit more complex vector calculation than it first looks. It has been too long since I last time needed to do such calculations, can't right a way say which force is greater, I would need to know tire frictions, accelerations actual height of the COG, torque at the wheels etc. etc.

A frictional force between the bottom of the tire and the road pushes the car forward (reaction to pushing the road backward). The vector is straight forward along the flat road surface. The higher the center of gravity, the bigger the radius for the torque to push the front end up. So a very low center of gravity will tend not to raise up the front very much. The height of the axle has nothing to do with it if the car can be modeled as a solid (which, in this case, is a good assumption).

If the center of gravity is, say, 1/4 the height of the center of gravity in a typical ICE, this should lead to much more traction for the front wheels of a Model X for a given thrust forward.

cerjor
"I would gladly accept 0-60 in 9 seconds to get appreciable additional range (50 miles). I will use the additional range much more often than a large acceleration."

For me it's the opposite. Only rarely will I go on a 300 (350) mile trip.

Daily I'll have the opportunity to enjoy the acceleration. And no more guilt from having to visit a gas station more often when "over-enjoying" it.

Accelerating an RWD car will always lift the front. The effect may be strong or weak depending on a variety of factors, and it may be close to zero, but it will always be positive. It's easy to see: Imagine you fixated the rear wheels. Now try to accelerate the car: What happens? Ever held a toy car between your thumb and index finger?

The idea that it makes a difference whether the COG is above the axle or below it, would apply if the axle was simply pushed straight forward. But it isn't. The force is applied to turn the wheels, and that "incidentally" makes the car move forward because the car "evades" being lifted up at the front (it would lift if the rear wheels couldn't move, as illustrated above).

On the topic of 0-60 in 9 seconds -- I think that would be acceptable to most if one assumes that interstates and similar roads provide enough on-ramp to accelerate to speed at that kind of acceleration. However as it stands I have had trouble in my Jetta which does 0-60 in 7s stock (although I've modified the car and it now does 60 faster than that).

Despite the way a lot of people drive and expect others to drive around here, the laws here state that it's the responsibility of the merging driver to match speed with traffic, find an opening, and move over. Finding an opening and merging with it may require more space than just accelerating to highway speeds. This means less room for actual acceleration as it has to be moderated for matching a hole in traffic.

I know there are cars on the road which have that kind of a 0-60 (9s+) on the road now, but they're also the ones I tend to have to switch lanes to allow on the interstate or slow down heavily for. Requiring others to move over for you is dangerous if there is even one inattentive driver.

I think the root problem is that the on-ramps are just too short for some of the interstates / highways they connect to (or perhaps speed limits too high). However in some places (like in downtown city areas) it's difficult to create longer on-ramps and would create other traffic issues to lower speed limits too far.

I'm not saying every car on the road needs to be a sports car, but I also think that vehicles which are underpowered for the roads they are driven on are unsafe just as vehicles driven too quickly are unsafe. It's possible to moderate speed and acceleration on a sufficiently powered car, but not possible to accelerate any faster than an underpowered car is able to.

@mwu: I agree with you. Some of the on ramps near me were designed for 1920-30 era cars which did not have to deal with such traffic or speeds. But I think the problem is more often the driver that doesn't use the power available correctly. How often does a tepid driver pull to the end of the acceleration lane and stop, then decide to go at some unpredictable time? Or doesn't know how to accept an invitation to enter the lane? Knowing when to put the foot down and how to time it seems the bigger problem.

That said, I will most definitely use the acceleration available to enter the highway with the least bother to those already traveling at speed. :)

Sorry, I guess I was considering the rear wheels as solid and applying the force at the axle where the car can rotate, but the force does originate at the tire contact patch. What I was confusing it with was that I was thinking of the "lean" of the sprung body of the car, which is a factor of its suspension and where the suspension attaches. I'm not sure the axle is the right point to consider for that either, it may be higher, but the angle of the COG to the point where the suspension attaches will affect which way the sprung body leans, even if the total car (unsprung frame and sprung body as a whole) is tilting the other way. So, you could have the body lean forward even as the front wheels are unweighted. If the suspension were solid then the only tilting behavior would be due to the tire contact patch and the angle of the COG to that. When you view it from the perspective of a passenger then they will notice the body leaning more, but when you view it at the wheels and their relative weighting it is only the tilt of the entire system that matters and that is dependent on angle of COG to the contact patches.

@BruceR, what you said about "how far forward of the rear wheels that will determine the torque necessary to lift the front end. The vertical portion of the center of gravity has little to do with the issue" is not correct either. What matters is the angle of the COG and moving it forward or moving it downward will both decrease that angle (well, downward as long as it is forward of the contact patch), so the vertical component *does* very much matter, it just isn't the only factor. We know that the models S and X will have a lower COG than most cars so they are in a better ballpark, but it could still be good or bad depending on where the COG is on a front to back basis - you need both measurements to do the trigonometry and determine the angle to the contact patch. Given how long and wide the battery pack is then I'd assume a larger 85kw battery pack would put the COG both low and also very close to the center of its footprint...

How far forward the center of gravity lies is important, but a case of diminishing returns. Viewed from the side, imagine an angled line from the (A) point of contact of the rear tire to the ground to (B) the center of gravity of the car. The lower that line is, the less the car will lift on acceleration.

Back to topic: the size of the battery is not the limitation. Clearly the 85 kWh battery can do 5.6 seconds with the standard PEM and motor. With the Performance version an upgraded PEM gives 4.4 seconds. The PEM and motor are almost certainly rate limiting. It is doubtful even a 150 kWh battery would make a difference. Of course a bigger,better battery would allow Tesla to build a bigger PEM and motor and thus some increase in acceleration.

I wouldn't pretend to know how to predict the limits but better batteries would also imply lighter batteries which would increase acceleration.

@William13 - "the size of the battery is not the limitation."

I don't think your conclusion/assertion (not sure which it is) is correct.

If you said "the size of the battery is not the only limitation," I would agree.

Put another way, if you replaced the battery in a Performance model with a shiny new (Tesla*) 40kWh it won't do 0-60mph in 4.4s. I'd be bet money on it.

* A different chemistry 40kWh might be able to pull it off, but not the chemistry that Tesla is using.

Actually, I suspect the 85kWh battery *is* the limitation on the Perf 4.4s. If it wasn't, Elon would have had the perf do 0-60 in 3.9s.

I always wondered why the 0-60 time is so important. Anything around 6-7 seconds is in my opinion more than enough. I care much more about range or anything else really.

Thing is that with BEV you don't lose anything with high performance. Unlike ICE more power doesn't equal worse efficiency, quite opposite. You get high power kind of accidentally.

0-60 time is helpful when entering motorways, but I think much more important is passing acceleration, the less time you need to stay on wrong lane the better. It is safety feature.

Also high acceleration is fun. Really fun. Dangerously fun in fact.

Also high acceleration is fun. Really fun. Dangerously fun in fact.
Nor is it illegal! (provided you don't cross the line into unsafe driving). I love accelerating from 0-65 coming out of a toll booth, with the state troopers sitting there. As long as you stop at 65, there's naught they can do....

The question of "downforce" appears here again; the shaping of the car, wings, etc., help provide traction. No matter how fat and sticky your tires, if they aren't being pressed onto the road firmly enough, you spin and burn rubber. And kinetic friction is much less effective than static.

On the moon, you'd need so much mass for traction that the inertia would require huge amounts of power to accelerate. (Maybe cats and cheetas have the right idea: claws and high, muscular, hindquarters!!)

Or an extensible set of narrow dragster wheels that project way out front and support the nose till you're up to speed, then lift and withdraw ...
:-O

Or with aero suspension, raise the rear and lower the nose ...


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