Tesla confirms Model 3 will have less than 60kWh battery option

[JRP3]

General Motors has already said that the Chevrolet BOLT has a battery pack that costs them something like $145 per kWh.

That is not correct. What GM said was that cell level costs were at that price, big difference, and LG Chem was pissed that GM said that publicly. I and others think that LG Chem gave GM essentially a loss leader cell price to get their business to build a good portion of the Bolt.

 

[JRP3]

I remember when the Chevrolet Corvette, with a 0.32 coefficient of drag, was the single most slippery production vehicle on the planet.

Aerodynamics are a function of cd and area, the Vette has a small area, so cdA is still low.

 

[SageBrush]

I may be off here, but if an extra kWh weighs about 10 kg and the car starts at say 1500 kg for a 200 mile range car, then the car is gaining about 0.67% in weight for every ~ 1.75% increase in battery capacity. Using an old rule of thumb that fuel economy changes are about 50% of weight changes, it suggests that 15-20% of every extra kWh is unrealized extra range.

At retail pricing of $500 - $600 per kWh, that adds up

 

[JRP3]

I still vehemently disagree with those who claim a 40-to-45 kWh capacity would be sufficient for either Performance or Range needs.

I'm expecting 50-55kWh.

 

[SageBrush]

I'm expecting 50-55kWh.

That is my guess as well.

 

[MP3Mike]

I may be off here, but if an extra kWh weighs about 10 kg

If I recall correctly for the Model S 85 the modules weigh ~4.4 kg/kWh. For the Model 3 it should be even lighter.

 

[SageBrush]

And people who buy the Tesla Model S will do so to blow the doors off of AUDI A8L, BMW 7-Series, Mercedes-Benz S-Class, and Porsche Panamera -- because they can.

Ahh ... so you think the cost premium will be valued for the car's acceleration.

Fair enough.

 

[AZ Desert Driver]

"there is a finite amount of space that can be taken up by the battery pack.

where would you suggest they put it on a Model 3?"


OK so I see the word Size and think a bigger battery means physically larger, yet what we are talking about here is not Size but in Capacity.
As I understand the battery construction - there are 7,000 or so batteries stacked in special arraignments. And that the lower Capacity battery is the same dimension as the higher capacity - they just put in blanks for the lower one. How many blanks? Enough to double the capacity in one skid to flex 55 kWh to 110 kWh? Probably not that many blanks...but 55 kWh to 85 kWh ??? No change in physical dimension of the skid - just weight and power and price.

Anyone want to calculate how many cells per battery size/capacity offered? If you built a skid capable of 110 kWh, could you blank it out to 55 kWh?

 

[JRP3]

I may be off here,

You are. Tesla is around 150Wh/kg at the pack level, which means each kWh is about 6.6kg, today. It will be less by the time the 3 is out.

 

[SageBrush]

If I recall correctly for the Model S 85 the modules weigh ~4.4 kg/kWh. For the Model 3 it should be even lighter.

I found this link that says 600 Kg for 85 kWh, or about 7 Kg/kWh.

So then 10 - 15% unrealized range gain.

Thanks for the correction

 

[MP3Mike]

I found this link that says 600 Kg for 85 kWh, or about 7 Kg/kWh.

So then 10 - 15% unrealized range gain.

Thanks for the correction

But you have to remember that ~150 of those Kgs don't change between battery sizes. (The battery pack assy., cables, etc.) So as the battery capacity increases the weight per kWh goes down.

 

[MP3Mike]

OK so I see the word Size and think a bigger battery means physically larger, yet what we are talking about here is not Size but in Capacity.
As I understand the battery construction - there are 7,000 or so batteries stacked in special arraignments. And that the lower Capacity battery is the same dimension as the higher capacity - they just put in blanks for the lower one. How many blanks? Enough to double the capacity in one skid to flex 55 kWh to 110 kWh? Probably not that many blanks...but 55 kWh to 85 kWh ??? No change in physical dimension of the skid - just weight and power and price.

Anyone want to calculate how many cells per battery size/capacity offered? If you built a skid capable of 110 kWh, could you blank it out to 55 kWh?

But the 85, and 95 kWh packs use the exact same size/number of cells. While the 70 kWh pack uses 888 fewer cells. (two modules) There are no blank cells in any of the current packs. (The 60 kWh pack did use blank cells.)

I suspect that Tesla won't make modules with blanks again, it is easier/more cost effective for every module to be the same. So they will either leave out modules and/or user lower capacity cells.

I doubt you could leave half of the cells out of a 110 kWh pack and still get decent performance in a 55 kWh pack.

 

[MP3Mike]

My guess is that the base model will be a Model 3 60, but it will have a ~58 kWh pack of which ~55 kWh will be available for use. (See they get to call it a 60, but still have smaller than a 60 kWh pack in it.)

 

[stopcrazypp]

I suspect that Tesla won't make modules with blanks again, it is easier/more cost effective for every module to be the same. So they will either leave out modules and/or user lower capacity cells.

I agree there will unlikely be blank cells this time. I would think Tesla learned lessons from the Model S and systematically designed the pack. However, I don't think they will use lower capacity cells, since that involves two chemistries (it is probably actually cheaper to just blank cells instead).

 

[Swampgator]

Read this article written last June. http://seekingalpha.com/article/3258855-will-teslas-model-3-compete
This guy is an engineer and basically backed into the configurations using known targets for energy density, cell size, etc. His predictions turned out to be almost 100% accurate from what we know so far. He predicted the wheelbase down to the fraction of an inch and was correct. He predicts 44 and 66 kwh batteries with range = 220 and 320 miles respectively (300 for the P366D)

 

[tomas]

Let's argue that Tesla hits $35k on time, makes the amazing car everybody expects and demands, and collects a nice profit per car along the way.

Then, how much will a MS with an 80 kWh pack cost, or why will people spend $70+ USD for it ?

They won't. And that's good for tesla. They'll buy the optioned up 3 rather than the entry level S. Which will be a much higher profit vehicle.

 

[JRP3]

He predicts 44 and 66 kwh batteries with range = 220 and 320 miles respectively (300 for the P366D)

He's almost certainly wrong about the base model being only 44kWh. He consistently over estimates the possible weight savings and their effects. A 44kWh pack would be about 42kWh usable at 95% of total capacity, which would mean 195Wh/mi efficiency would be needed to hit 215 miles of range. The Model S 85 with 77kWh usable does 290Wh/mi to get 265 miles EPA.

 

[Topher]

Tesla has a huge head start on how to design and optimize a BEV.

Drag coefficients have been known about since the time of the Tatra 77 (Cd of 0.212) back in 1935. If ICE car manufacturers didn't USE their head start...

Thank you kindly.

 

[SageBrush]

He's almost certainly wrong about the base model being only 44kWh. He consistently over estimates the possible weight savings and their effects. A 44kWh pack would be about 42kWh usable at 95% of total capacity, which would mean 195Wh/mi efficiency would be needed to hit 215 miles of range. The Model S 85 with 77kWh usable does 290Wh/mi to get 265 miles EPA.

Good way to think about this question, since it makes clear that an average 195/290 = 67%, or 33% reduction in friction forces is required.

Since total road and aero friction can be estimated as
mg*v + Rho*CdA*v*v,
the constants and speeds are the same so we are left with
delta_mass + delta_CdA

Cd will drop from 0.24 to 0.21 optimistically,
And perhaps frontal area 10% less
for a total CdA decrease of 21%

Since the car is reported to be 20% less volume I have been guessing 20% less weight

On both sides of the expression we are only 2/3rds of the way towards required reductions.

--
Leaving the car as described implies about 230 Wh/mile, or 50 kWh for 215 miles. I'm still not clear where the anti-bricking buffer is included in these battery capacity guesses.

 

[Red Sage]

That is not correct. What GM said was that cell level costs were at that price, big difference, and LG Chem was pissed that GM said that publicly. I and others think that LG Chem gave GM essentially a loss leader cell price to get their business to build a good portion of the Bolt.

I always quote cell level pricing anyway. Sure, the casing... modules... power electronics... invertors... et al may add some cost. But I figure the cell level pricing is the bulk of it all.

Once again, most reports I've seen have estimated that Tesla Motors' cost is as low as $180 per kWh and as high as $240 per kWh... And yes, that is at the cell level... Relative to what they have paid Panasonic for 18650 cells.

Thus, I expect that a 30% minimum reduction will put them somewhere between $126-to-$168 per kWh at the very start for Generation III vehicles. If it ends up being as much as a 40% or 50% reduction from the Gigafactory instead? The range drops to $108-to-$144 per kWh or $90-to-$120 per kWh instead.

I see good times ahead.