2017 Investor Roundtable:General Discussion

[ValueAnalyst]

Even if that's the case, I believe folks are overly optimistic about range gains. (And I actually think some folks think that 2170 cell based kWh are somehow better than 18650 cell kWh... but a kWh, is a kWh, but that's a separate discussion)

Let's look at it a different way:

A Model 3 is about 80% the size of a Model S. A Model S RWD weighs about 4,700lbs. Likely the Model 3 will have less options, reducing some weight. But it also will incorporate more steel rather than aluminum, increasing weight. Let's say those cancel out and use 80% as our mass target, that's 3,760lbs.

A weight savings of 233lbs is only a 6% decrees in mass. Yet the idea that you can reduce the battery capacity by 17% (from 60kWh to 50kWh), and expect to go the same distance doesn't makes sense.

Again this is particularly because the mass comes in to play primarily during acceleration/deceleration. It has some impact on rolling resistance. It has zero impact on aerodynamic forces.

As such, I'd expect that 6% mass reduction to have perhaps maybe 1-2% actual range impact. Not nearly enough to shave 10kWh off the battery and expect to go the same distance.

My projection relies mostly on battery energy density improvement year-after-year that approximate 5-8% per year rather than weight reduction.

https://www.quora.com/Is-it-true-that-battery-energy-density-improves-5-8-per-year

This was the primary reason why I said Tesla could maybe use a 50 kWh battery for Model 3/Y by 2020, while keeping range at ~250-300.

I did not see energy density improvement anywhere in your calculation. What am I missing?

 

[jhm]

Because they dont make any Gigawatts in Fremont. GF2 is supposed to pumping out panels and solar roof tiles at a rate of multiple Gigawatts per year. If battery densities continue to rise, do we think they will be building Terafactories at some point with combined Battery and Solar output of 1000GW/Y. Thats a lot of cars and roof tiles. 20% of the new roof market (20% of 5M/Y) would be 5GW with an average sized 5KW system so probably no Terafactories required. You would want to spread out the Gigafactories to shorten the supply chain and get closer to where the product is going to be used.

We could quantify vehicle production in GW too! Motor power output, battery size, take your pick.

 

[MP3Mike]

My projection relies mostly on battery energy density improvement year-after-year that approximate 5-8% per year rather than weight reduction.

This was the primary reason why I said Tesla could maybe use a 50 kWh battery for Model 3/Y by 2020, while keeping range at ~250-300.

This makes absolutely no sense. A 50kWh battery is a 50kWh battery no matter if it weighs 1200 lbs or 1080 lbs. The only additional mileage you get would be from the weight reduction. (Unless the volume reduction is so great that they can reduce the aero drag significantly.)

Now if what you are really saying is that by 2020 they can fit a 65 kWh battery in the same space and with the same weight as a 50kWh battery is today that is a whole different thing. (They would be using a 65kWh battery not a 50kWh battery.)

 

[ValueAnalyst]

This makes absolutely no sense. A 50kWh battery is a 50kWh battery no matter if it weighs 1200 lbs or 1080 lbs. The only additional mileage you get would be from the weight reduction. (Unless the volume reduction is so great that they can reduce the aero drag significantly.)

Maybe I haven't made my question/point clear. Let me try again, and if you still think it makes no sense, I'll drop it.

Due to the 5-8% battery density improvement that seems to be the trend, can Tesla reduce the battery size on a base model Model 3 from, say 60 kWh in 2017, to 50 kWh in 2020, and still keep the range the same (~250-300 miles, or whatever it's gonna be this year)?

This is important because Tesla then can produce more cars with its Gigafactories.

 

[MP3Mike]

Due to the 5-8% battery density improvement that seems to be the trend, can Tesla reduce the battery size on a base model Model 3 from, say 60 kWh in 2017, to 50 kWh, and still keep the range the same (~250-300 miles, or whatever it's gonna be this year)?

No that isn't how it works. If you have a 50kWh battery and you increase energy density by 8% you now have a 50kWh battery that weighs 8% less. It still only has 50kWh of stored energy. (Or you can create a 54kWh battery that weighs the same as the original 50kWh battery.)

 

[techmaven]

A 50kWh battery is a 50kWh battery no matter if it weighs 1200 lbs or 1080 lbs. The only additional mileage you get would be from the weight reduction. (Unless the volume reduction is so great that they can reduce the aero drag significantly.)

Due to the way EPA and NEDC has established their testing metrics, the weight has a big effect on rated range. The tests over-emphasize the acceleration and deceleration efficiency. Now, does it have as big of an impact on real world 2+ hour driving on the highway? No. But it will have an outsized impact on rated range. It's unfortunate that rated range is based on combined MPGe which is based on 55% city, 45% highway testing. And the highway testing metrics are not representative of high speed steady cruising, even the "high speed" test.

 

[DurandalAI]

Maybe I haven't made my point clear. Let me try again, and if you still think it makes no sense, I'll drop it.

Due to the 5-8% battery density improvement that seems to be the trend, can Tesla reduce the battery size on a base model Model 3 from, say 60 kWh in 2017, to 50 kWh in 2020, and still keep the range the same (~250-300 miles, or whatever it's gonna be this year)?

This is important because Tesla then can produce more cars with its Gigafactories.

VA, I think you're stuck on the battery density issue. It may reduce the weight, but the weight is only one aspect of the energy required for moving the vehicle. Coefficient of drag is a large issue, as is motor/inverter efficiency. In order to achieve the same range between a 60kWh battery and a 50kWh battery at say 250 miles is: 4.166mi/kWh at 60kWh compared to 5mi/kWh at 50kWh. You won't get that much of an efficiency increase with anything less than a 50% drop in battery weight, and even that is doubtful. The efficiency is highly tied to the speed you're driving, the coefficient of drag, rate of acceleration, and lastly the weight of the vehicle.

I see where you're trying to go with it, but you simply cannot compensate for 10kWh of battery pack with 5-10% weight reduction alone.

 

[Reciprocity]

Maybe I haven't made my point clear. Let me try again, and if you still think it makes no sense, I'll drop it.

Due to the 5-8% battery density improvement that seems to be the trend, can Tesla reduce the battery size on a base model Model 3 from, say 60 kWh in 2017, to 50 kWh, and still keep the range the same (~250-300 miles, or whatever it's gonna be this year)?

This is important because Tesla then can produce more cars with its Gigafactories.

VA, the issue is terminology. You are both right but not using the same language. VA is saying the batteries are getting more efficient to make by 7% per year. The gigafactory is still making 60KWh batteries, but they are able to do it at the cost of a 50KWh pack and all the resources required are more efficient in the process, including the factory. So yes, a gigafactory at 100GWh/Y will be able to produce ~107 next year and ~115 the year after. They will still be making 60KWh packs but with materials that would be required for 50KWh pack a couple of years earlier. Mostly the same machinery, just improvements to the l chemistry and materials used.

 

[ValueAnalyst]

No that isn't how it works. If you have a 50kWh battery and you increase energy density by 8% you now have a 50kWh battery that weighs 8% less. It still only has 50kWh of stored energy. (Or you can create a 54kWh battery that weighs the same as the original 50kWh battery.)

I think we're saying the same thing...

Doesn't the 54 kWh battery have 8% more range than 50 kWh battery?

So the reciprocal would be: Tesla could reduce base model battery size from 54 kWh in one year to 50 kWh to the next while keeping the range the same.

Yes?

 

[ValueAnalyst]

VA, the issue is terminology. You are both right but not using the same language. VA is saying the batteries are getting more efficient to make by 7% per year. The gigafactory is still making 60KWh batteries, but they are able to do it at the cost of a 50KWh pack and all the resources required are more efficient in the process, including the factory. So yes, a gigafactory at 100GWh/Y will be able to produce ~107 next year and ~115 the year after. They will still be making 60KWh packs but with materials that would be required for 50KWh pack a couple of years earlier. Mostly the same machinery, just improvements to the l chemistry and materials used.

Exactly.

 

[jhm]

Maybe I haven't made my question/point clear. Let me try again, and if you still think it makes no sense, I'll drop it.

Due to the 5-8% battery density improvement that seems to be the trend, can Tesla reduce the battery size on a base model Model 3 from, say 60 kWh in 2017, to 50 kWh in 2020, and still keep the range the same (~250-300 miles, or whatever it's gonna be this year)?

This is important because Tesla then can produce more cars with its Gigafactories.

Just denominate your battery in kg rather than kWh.

 

[MP3Mike]

Doesn't the 54 kWh battery have 8% more range than 50 kWh battery?

Yes.

So the reciprocal would be: Tesla could reduce base model battery size from 54 kWh in one year to 50 kWh to the next while keeping the range the same.

No.

 

[ValueAnalyst]

Alright; I give up. For now.

I have finance/accounting/econ background. Last time I did physics was in middle school.

Although I won some first place award then, I clearly need a refresher. Where's my RosettaStone for Physics?

 

[JRP3]

Due to the 5-8% battery density improvement that seems to be the trend, can Tesla reduce the battery size on a base model Model 3 from, say 60 kWh in 2017, to 50 kWh in 2020, and still keep the range the same (~250-300 miles, or whatever it's gonna be this year)?

Due to the way EPA and NEDC has established their testing metrics, the weight has a big effect on rated range. The tests over-emphasize the acceleration and deceleration efficiency. Now, does it have as big of an impact on real world 2+ hour driving on the highway? No. But it will have an outsized impact on rated range. It's unfortunate that rated range is based on combined MPGe which is based on 55% city, 45% highway testing. And the highway testing metrics are not representative of high speed steady cruising, even the "high speed" test.

Right, and because Tesla realizes the real world importance of highway range over EPA I don't expect they would use energy density increases as a way to decrease pack size while keeping EPA range the same while sacrificing highway range.

 

[DurandalAI]

I think we're saying the same thing...

Doesn't the 54 kWh battery have 8% more range than 50 kWh battery?

So the reciprocal would be: Tesla could reduce base model battery size from 54 kWh in one year to 50 kWh to the next while keeping the range the same.

Yes?

Nope.
Range would not be the same. Consumption is mostly tied to speed and CoD, followed by weight of the car. Only so much to be gained by weight reduction. I recommend checking out ecomodder.com

 

[dalalsid]

Alright; I give up. For now.

I have finance/accounting/econ background. Last time I did physics was in middle school.

Although I won some first place award then, I clearly need a refresher. Where's my RosettaStone for Physics?

Haha - it is simple -> more densitty = more kWh in the same space/weight so higher density = higher kWh = more range.

 

[scaesare]

My projection relies mostly on battery energy density improvement year-after-year that approximate 5-8% per year rather than weight reduction.

https://www.quora.com/Is-it-true-that-battery-energy-density-improves-5-8-per-year

This was the primary reason why I said Tesla could maybe use a 50 kWh battery for Model 3/Y by 2020, while keeping range at ~250-300.

I did not see energy density improvement anywhere in your calculation. What am I missing?

Perhaps you can explain to me how believe energy density gain allow you to go from a 60kWh pack to a 50kWh pack (a 17% reduction in capacity), and go the same distance?

 

[scaesare]

Due to the 5-8% battery density improvement that seems to be the trend, can Tesla reduce the battery size on a base model Model 3 from, say 60 kWh in 2017, to 50 kWh in 2020, and still keep the range the same (~250-300 miles, or whatever it's gonna be this year)?

Why? A kWh is a kWh.

Energy capacity is like gallons. A gallon is a gallon.

You can carry it in large unwieldy container (a wheel barrow aka 18650 current cell chemistry) or a more streamlined or efficient container (a gallon jug aka 2170 next-gen chemistry), but if you need 5 gallons of water, you can't get away with 4 "more efficient" gallons.

The same with the car. If it requires 250watt-hours per mile to move down the road (due to mass, rolling resistance, aero, etc..) then it doesn't matter what "form" that energy is stored in. All you can do is reduce one of the factors (like mass/weight) to make the car somehow more efficient, then you can reduce the energy it takes to move the card down the road.

(This is what I meant by the misperception I suspect some folks have that somehow kilowatt-hours from a 2170 cell are somehow "better" in terms of the locomotive force they allow.)

 

[scaesare]

Due to the way EPA and NEDC has established their testing metrics, the weight has a big effect on rated range. The tests over-emphasize the acceleration and deceleration efficiency. Now, does it have as big of an impact on real world 2+ hour driving on the highway? No. But it will have an outsized impact on rated range. It's unfortunate that rated range is based on combined MPGe which is based on 55% city, 45% highway testing. And the highway testing metrics are not representative of high speed steady cruising, even the "high speed" test.

This is unfortunately true.

But I don't believe that EPA numbers would support the claims being made here made here... a ~230 lb reduction won't result in a ~17% mileage gain on a 3,800 lb car, even with the skewed EPA testing.

 

[scaesare]

I think we're saying the same thing...

Doesn't the 54 kWh battery have 8% more range than 50 kWh battery?

So the reciprocal would be: Tesla could reduce base model battery size from 54 kWh in one year to 50 kWh to the next while keeping the range the same.

Yes?

But that's NOT what you said:

if Model 3/Y can achieve 300 mile range with 50 kWh battery due to 7% per year improvements