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Model 3 to start at 60kWh

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That's because of the high air resistance that Model X have. Model X 90D have 90 mpg city and 94 mpg highway. Model S on the other hand have 95 mpg city and 106 mpg highway. If Tesla have made sure that Model 3 have really low air resistance it should have longer range on highway according to EPA.

yeah at high speeds the cd becomes more and more important. I wouldn't be surprised at all if the Model 3 75kwh gets a similar range at high speeds (160kmh+) like 85kw Model S. My old 3 series (petrol) uses like 7-8L/100km cruising at 120-130kmh and probably around 10-11L/100km crusing at 200kmh. My dads 5 series wagon (diesel) uses ~4-5L/100km crusing at 130kmh and then like 13-14L/100km at 200kmh.
 
There has been plenty of napkin math done on here by people smarter than me that would suggest 4mi/kWh isn't too far fetched. 2170 cells, lighter weight, better drag coefficient......

The P90D gets ~3.26 mi/kWh.... So not outside the realm of possibility.
(emphasis mine)

While I do agree that 4mi/kWh is a reasonable estimate, I'd point out that the cell type doesn't matter, except for it's lesser mass (and perhaps volume), whch you already state separately.

A kWh is a kWh as far as the car is concerned. For efficiencies' sake, it doesn't matter if that comes from 2170's, 18650's, or prismatic cells, when it comes to energy used per mile.

Now, of course more energy dense cells mean you can get more total energy capacity onboard, but that's not what's being talked about here.
 
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While I do agree that 4mi/kWh is a reasonable estimate
As a first approximation for long distance travel mode, it comes down to differences in Cd

Model S is 0.26
Say Model 3 is 0.21

Then consumption rate in kWh/mile = 3.26/(0.21/0.26) = 4.03
Or about 133 MPGe highway for people who like that unit

PS: ignore the appearance of accuracy; I'm just agreeing with the estimated 4 miles/kWh
 
(emphasis mine)

While I do agree that 4mi/kWh is a reasonable estimate, I'd point out that the cell type doesn't matter, except for it's lesser mass (and perhaps volume), whch you already state separately.

A kWh is a kWh as far as the car is concerned. For efficiencies' sake, it doesn't matter if that comes from 2170's, 18650's, or prismatic cells, when it comes to energy used per mile.

Now, of course more energy dense cells mean you can get more total energy capacity onboard, but that's not what's being talked about here.
i meant it from an efficiency standpoint, which likely comes from needing less weight to store the same amount of energy.
 
Volume of vehicle production greatly outweighs the need for individual mass market vehicle range in the near term. If the battery cell output is the limiting factor to ramp up production capacity, then I'd expect the smallest capacity pack to achieve 215 EPA miles being available first and Elon suggesting you buy the S for more range.

I see this as more of a capacity driven factor over anything else. How many 3's can they deliver with the resources currently available. When gigafactory capacity ramps up they can/will offer larger battery packs at that time - doesn't have to be Day 1.

Would shareholders rather tesla deliver 100k vehicles in 2017 with 55 kWh packs and ~215 miles range or 90k vehicles with 60 kWh packs and ~235 mile range? Shareholders want productionquality volume delivered and expect mix to change over time and won't be bothered by range that meets published targets.
 
A kWh is a kWh as far as the car is concerned. For efficiencies' sake, it doesn't matter if that comes from 2170's, 18650's, or prismatic cells, when it comes to energy used per mile.
Not exactly.
Batteries have this thing called internal resistance. You do not get the same amount of kWh out of them when you discharge at X kW or Y kW. Heavier car will see higher average discharge and thus lower amount of kWh that came out of the same battery before it declared empty. Because the internal resistance losses will be higher.
2170 are expected to weigh less, same nominal capacity will thus yield more "useful" kWh in practice.
Exactly how big this difference is is subject to many factors.
 
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As a first approximation for long distance travel mode, it comes down to differences in Cd

Model S is 0.26
Say Model 3 is 0.21

Then consumption rate in kWh/mile = 3.26/(0.21/0.26) = 4.03
Or about 133 MPGe highway for people who like that unit

PS: ignore the appearance of accuracy; I'm just agreeing with the estimated 4 miles/kWh
The Cd is just the shape, you need to know the frontal area two. And the Cd for Model S and Model X is 0.24.
 
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The Cd is just the shape, you need to know the frontal area two
Elon has said that the Model 3 is 80% of the volume of the Model S and we now know that the Model 3 length is 95% of the S. It follows that the frontal area has to be 85% of the S. So then CdA of Model 3 is (21/24)*0.85 that of Model S, equal to 74%

the Cd for Model S and Model X is 0.24
Thanks for the correction.

At highway speeds of 70 mph (113 kph) Aero accounts for 2/3rds of total friction forces to overcome so the Cd difference has to be weighted accordingly. I figured that the difference is mass between the two cars makes up that difference.
 
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i meant it from an efficiency standpoint, which likely comes from needing less weight to store the same amount of energy.

I understand, it's just that you already mentioned "lighter weight", as the very next item:

ModelNforNerd said:
...2170 cells, lighter weight...

I wanted to clarify that energy delivered from a 2170 is not a factor of it's own, as it's a mistake I've seen posted here previously.
 
Not exactly.
Batteries have this thing called internal resistance. You do not get the same amount of kWh out of them when you discharge at X kW or Y kW. Heavier car will see higher average discharge and thus lower amount of kWh that came out of the same battery before it declared empty. Because the internal resistance losses will be higher.
2170 are expected to weigh less, same nominal capacity will thus yield more "useful" kWh in practice.
Exactly how big this difference is is subject to many factors.

Actually, in this context it is.

We are talking about how much energy the car consumes per mile. This is what is delivered to the car after any losses incurred by the pack, interconnects, internal resistance, etc...

Certainly cell designs will impact some of those characteristics. That can have to do with chemistry, anode design, cathode design, interconnects, etc... and different physical cell layouts may or may not impact that.

But a car that needs 240Wh/mi doesn't care about cell internal resistance. You may get less overall energy delivered from the pack, which will ultimately affect range, but that doesn't change the efficiencies of the car as determined by drivetrain efficiency. aerodynamics, rolling resistance, etc...
 
But a car that needs 240Wh/mi doesn't care about cell internal resistance.
One might say you have to consider cell resistance as part of the drivetrain efficiency. If we had lightweight energy dense ultracapacitors, it'd be no big deal and you could ignore it, but with lithium cells you can't accurately calculate overall vehicle efficiency accurately without taking this into account.

Otherwise it's unclear where you get the numbers from: after the losses from the pack, interconnects, internal resistance, losses from the inverter, losses from the motor, losses from the mechanical linkage, losses from the tire rolling resistance, aerodynamic losses??? What speed are you going? Is there wind? Are there occupants in the car? Are they fat? :p

Each factor plays a part in overall efficiency. With the 2170s for Model 3 being more energy dense than 18650s and therefore lighter per kWh the same vehicle with absolutely no other changes besides 18650s to 2170s with the same capacity, the 2170 vehicle should be able to travel further unless there were negative impacts to internal resistance from the new chemistry, which shouldn't be the case.

When there are no changes but the cells, as you've mentioned the energy usage for all other parts of the vehicle remain relatively unchanged (rolling resistance will change because the vehicle is lighter).
 
One might say you have to consider cell resistance as part of the drivetrain efficiency.

Somebody might, but that's not accurate in this context of talking about vehicle efficiency.

Cell losses due to internal resistance are... well... internal.

Thus from a vehicle consumption perspective it doesn't know if it received 1kWh from a battery with high loss or low. If it takes 240Wh to go one, mile, then it takes 240Wh. Now if the battery actually expended 300Wh, and due to internal losses burned 60 of those as heat, then you have a poorly suited battery for this application, and it will be difficult to extract it's rated capacity.

But a pack unable to deliver it's rated capacity, has no bearing on if the car requires 240Wh to go one mile due to aero, friction, mass, etc...

With the 2170s for Model 3 being more energy dense than 18650s and therefore lighter per kWh the same vehicle

Perhaps you missed the part where I pointed out where mass was already addressed separately in the post I was referring to?
 
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Perhaps you missed the part where I pointed out where mass was already addressed separately in the post I was referring to?
While you did address it, you had seemed to be disagreeing with a post from @ModelNforNerd which was implying simply that 2170s will be lighter weight per kWh and therefore will have a higher range. While kWh is kWh, 60 kWh from 18650s will not go as far as 60 kWh from 2170s.

Maybe you weren't disagreeing at all?...
 
Somebody might, but that's not accurate in this context of talking about vehicle efficiency.

Cell losses due to internal resistance are... well... internal.

Thus from a vehicle consumption perspective it doesn't know if it received 1kWh from a battery with high loss or low. If it takes 240Wh to go one, mile, then it takes 240Wh. Now if the battery actually expended 300Wh, and due to internal losses burned 60 of those as heat, then you have a poorly suited battery for this application, and it will be difficult to extract it's rated capacity.

But a pack unable to deliver it's rated capacity, has no bearing on if the car requires 240Wh to go one mile due to aero, friction, mass, etc...



Perhaps you missed the part where I pointed out where mass was already addressed separately in the post I was referring to?
The rated capacity of a cell/pack is based on a certain C-rate (sometimes a very low one). A pack operated in a higher C-rate will give less capacity.

For example here, a cell discharged at 0.2A has 12.1 Wh of energy. At 5A has 10.3 Wh of energy. This does matter in testing.
Test of Panasonic NCR18650B 3400mAh (Green)

The EPA range test is done by fully charging the car. The MPGe figure includes charging losses (it's the AC electricity). So such IR losses are counted into this.
 
While you did address it, you had seemed to be disagreeing with a post from @ModelNforNerd which was implying simply that 2170s will be lighter weight per kWh and therefore will have a higher range.

I disagreed that cell format in and of itself changes the efficiency equation of the car.

If energy density goes up (due to chemistry, change, etc...), then you are moving less mass for a given total energy capacity. That will help efficiency. However, energy density is independent of format size.

JeffK said:
While kWh is kWh, 60 kWh from 18650s will not go as far as 60 kWh from 2170s.

This I also disagree with.

That's like saying 5 gallons of water from two 2.5 gal jugs is more than 5 gallons from five 1 gal jugs.

Thought experiment:

A new battery chemistry yields 10 watt/hours per gram.

You use 1Kg of this battery material and roll it in to 18650's to make pack A

You also use 1Kg of this material and roll in in to fewer 2170's to make pack B.

Q1: What is the energy capacity of each pack?

Q2: How far could a car that uses 250kWh/mi travel on either pack, all else being equal?
 
The rated capacity of a cell/pack is based on a certain C-rate (sometimes a very low one). A pack operated in a higher C-rate will give less capacity.

For example here, a cell discharged at 0.2A has 12.1 Wh of energy. At 5A has 10.3 Wh of energy. This does matter in testing.
Test of Panasonic NCR18650B 3400mAh (Green)

The EPA range test is done by fully charging the car. The MPGe figure includes charging losses (it's the AC electricity). So such IR losses are counted into this.

Neither of which:

A) Has necessarily to do with format size

B) Changes the efficiency of the car and thus it's power requirement
 
That's like saying 5 gallons of water from two 2.5 gal jugs is more than 5 gallons from five 1 gal jugs.
Five gallons of water might weigh more with five 1 gallon jugs due to the containers themselves. In addition, five 1 gallon jugs will also take up more volume for 5 gallons and thus be less dense.

Does that make sense? Besides chemistry, which we know is going to be different, the cell format does matter.