Model 3 Battery size

[arnis]

If we assume the same ratio for the Model 3, it should weigh 8.814*153.38= 1352 kg without motors and the battery. It is possible to argue that the Model 3 should weigh more per square meter because it will have a steel frame instead of aluminum. However, the Model 3 won't have a dashboard, no second computer to power the dashboard and only 1.5km wiring instead of 3km. So I think these will balance out the steel vs aluminum frame weight difference.

First of all, nice work. I still suspect 55/70 combination, but 55/75 is not far away. I think they will push to 75 a year later.
I still disagree about weight per square meter being equal due to next presumptions:
there will be less luggage space on Model 3 - smaller trunk and smaller frunk - higher overall structural density.
Also it appears that the front bumper is stubbier, so less air more density there too.
Though I expect Model 3 (base) have manually adjustable seats (considerable weight saving)
there will be more glass on standard model (rear window) - glass weights more than sheet metal.
Reducing wiring by 50% and removing speedo cluster will not balance out the use of steel.
But I don't expect Tesla switching to "everything steel", rather than only unibody, maybe doors/hatches too;
most likely front and rear subframes will be aluminum.
Also i expect battery weight per square meter to be higher. Due to better design and due to 2170 making pack thicker.

I would mention again, that making Model 3 longer distance than Model S would be like shooting yourself into the foot.

 

[JRP3]

They are going with aluminum cabling for high power handling. Some weight savings there.
Tesla Model 3: supplier says it received an order for 3,000 km of ‘shielded aluminum cables’ from Tesla

 

[JoseBQ]

All these calculations on range only takes into account drag coefficients, weight and rolling resistance.

Does anyone have an idea about improvements in electronics, motor and energy conversion? Could it be a nice surprise?

I'm thinking about the hyundai ionic whose efficiency is remarkable and not only for its weight, rolling resistance and drag coefficient.

 

[Troy]

Hi @arnis.

Also I expect battery weight per square meter to be higher.

Pack weight is not included in the square meter calculations. I found a document HERE that has data Tesla has sent to the US Department of Energy. In the document, it shows 85 kWh pack weight at 545 kg and the vehicle curb weight as delivered at 4,514 pounds (2048 kg). I subtracted pack weight and motor weights before square meter calculations. Then I added pack weight and motor weight back based on the Model 3 configuration.

Here is my detailed calculation:
85 kWh Model S pack weight = 545 kg (source)
Pack housing weight = 114 kg (Source WK057)
Weight of all modules in the 85 kWh pack = 545-114= 431 kg
Actual battery capacity in 85 kWh pack = 81.5 (source)
Module weight per kWh = 431/81.5= 5.29 kg/kWh

Then I calculated the Model 3 55 kWh pack as follows:
Pack housing weight = 91 kg. This is a guess. The Model 3 pack should be smaller than the Model S pack.
Actual battery capacity in 55 kWh pack = 55.79 (based on 60,70,75,100 kWh pack data)
Weight of all modules in the 55 kWh pack = 5.29 kg/kWh* 55.79 kWh * 0.83= 245 kg. Here 0.83 represents energy density improvements.
Total pack weight = 245+91= 336 kg

I would mention again, that making Model 3 longer distance than Model S would be like shooting yourself in the foot.

I disagree. The Model 3 will be better than the Model S for long distance travel because it will supercharge faster. Both cars will have the same cabin space. Model S 75D has 259 mi rated range. The Model 3 75D will have 300 miles rated range because the car is more efficient.

Now, some people might say both 75 kWh batteries would supercharge to 100% at the same time. That's correct but let's say you need to leave this supercharger with 245 mi rated range to skip one and go to the next one. 245 rated miles means 245/259= 94.6% supercharging in the Model S 75D but only 245/300= 81.7% in the Model 3 75D.

The Model 3 will make it possible to avoid supercharging close to 100% and that makes a big difference because supercharging slows down a lot when you get close to 100%. In addition, after a year or two, the battery degrades 5% and then stays around 95% capacity for many years. That means the Model S 75D will have 246 mi rated range for most of the life of the vehicle while the Model 3 75D will have 285 miles. After the first year, long distance trips in the Model S 75D will be even more difficult.

 

[arnis]

Does anyone have an idea about improvements in electronics, motor and energy conversion?

Yes, I read somewhere that Tesla found more efficient semiconductors for the motor inverters.
Even a slight change there will be noticeable.

 

[arnis]

I disagree. The Model 3 will be better than the Model S for long distance travel because it will supercharge faster.

Supercharging speed is only one factor for long distance traveling. There are dozens of other variables.
Model 3 is more like urban vehicle than touring vehicle. Model S is more touring vehicle than city vehicle - it can carry lots of luggage. It's not a small vehicle and is not extremely suitable for cities (I will exclude US, AFAIK parking spots are much bigger there).
Vehicles with longer wheelbases behave better on highways. Model 3 will have shorter wheelbase.
So the concept of Model 3 is to be a shorter commute vehicle than Model S though both will be long-distance EV-s.

Also I don't expect Model 3 will charge faster (power not distance) as it will definitely have less cooling capability.
It will definitely have only one AC condenser while Model S/X has more. Also air intake opening surface area appears to be smaller.
On Model S/X the main limitation for charging speed is thermal balance, not C-rate nor SC output.
Therefore, even 200kWh Model 3 will very likely not charge at 120kW rate for long (in warm/mild weather).
Cell form factor doesn't change charging efficiency. I don't expect 2170 cells will have a new chemistry compared to latest S/X.
Though they should be able to sustain higher C-rates.

Also I don't expect Tesla going hard-core with M3 SC-capabilities. I still think Model S/X platform will be the flagship, even in this category.
Though due to more efficient vehicle, range gained per minute at SC might be very similar to Model S.

Tesla should make Model 3 a better vehicle than any other EV. But they won't make it better than their own flagships.
Most EV-s charge at 50kW max. Ioniq can go up to 70kW. If Model 3 goes up to 100kW that will be class-leader for years.
Even new Jaguar (while having 90kWh pack) might not do 70kW. Same with Bolt.
I personally expect 80kW rate for the 70/75 pack.

 

[Troy]

Also I don't expect Model 3 will charge faster (power not distance) as it will definitely have less cooling capability.

Yes, both the Model S 75D and Model 3 75D will charge to 100% at the same time. The power rate they can take is identical. However, the reason Model 3 will supercharge faster than the Model S is because it can go further per kWh. Let me exaggerate the numbers so it becomes clearer:

Car A and Car B both have a 10 kWh battery that charges to 100% in 10 minutes.

Car A has 10 miles range. Therefore the charge rate is 10miles/10 minutes = 1 miles per minute
Car B has 50 miles range. Therefore the charge rate is 50miles/10 minutes = 5 miles per minute

In this example, the batteries and the chargers are identical but because one of the cars has 5 times more range, it will charge 5 times faster.

 

[scaesare]

Man a lot of speculation here with very little supporting evidence cited...

 

[scaesare]

because one of the cars has 5 times more range, it will charge 5 times faster

That's like saying you can pump 10 gallons of fuel in to a Prius faster than a Hummer.

No, they fill at the same rate. One is simply more efficient than the other.

Example #2: Is a Model S Supercharging at 120kW in the winter charging more slowly than one charging at 120kW in the summer, simply because the pack heater causes it to consume more watt-hrs per mile in the cold?

Charging rate is tied to how quickly cells take on energy, (c-rate), not what the vehicle does with that energy after the fact.

 

[JohnSnowNW]

That's like saying you can pump 10 gallons of fuel in to a Prius faster than a Hummer.

No, they fill at the same rate. One is simply more efficient than the other.

Example #2: Is a Model S Supercharging at 120kW in the winter charging more slowly than one charging at 120kW in the summer, simply because the pack heater causes it to consume more watt-hrs per mile in the cold?

Charging rate is tied to how quickly cells take on energy, (c-rate), not what the vehicle does with that energy after the fact.

He's not talking about charge rate, he's talking about travel time. Travel time is reduced if you can charge more miles in the same amount of time.

 

[scaesare]

He's not talking about charge rate, he's talking about travel time. Travel time is reduced if you can charge more miles in the same amount of time.

Read his words I quoted...

 

[Troy]

There is no error with the terminology I've used. In the example, I said, "charge rate is x miles per minute". Miles added per time is the charge rate. Model 3 75D will add more miles per minute than the Model S 75D. Therefore the charge rate will be higher.

I recommend adding spam users to your ignore list. Click on the username. Then on the top right click "ignore".

 

[JRP3]

Yes, I read somewhere that Tesla found more efficient semiconductors for the motor inverters.
Even a slight change there will be noticeable.

Inverters are already probably better than 90% efficient, a percent or two improvement would mean 2-4 miles on a 200 mile pack. So yes there could be something but no big surprises.

 

[JRP3]

I recommend adding spam users to your ignore list. Click on the username. Then on the top right click "ignore".

I recommend not ignoring the more technically knowledgeable members on this forum just because you may disagree with them.

 

[scaesare]

There is no error with the terminology I've used. In the example, I said, "charge rate is x miles per minute". Miles added per time is the charge rate. Model 3 75D will add more miles per minute than the Model S 75D. Therefore the charge rate will be higher.

You are conflating charge time and range accumulation rate.

When you use terms such as:

the reason Model 3 will supercharge faster...
...it will charge 5 times faster.

They refer to charging, which is the definition of a battery accumulating charge, and the speed (i.e. how much faster) that happens.

Now, for a given vehicle, you will accumulate range as a function of that charge, and energy the car will subsequently believes it will consume to go a mile. So although that display is nice, what it really is an estimate. And not even an accurate one, as it averages the entre session over the course of the charge taper.

What happens if you change your display to "ideal" miles? Are you charging faster?

What if you plan on using the heater and driving in to a headwind? Are you charging more slowly?

What happens of you change the display to read in kWh instead if miles per hour of charge? Have you disrupted the space-time continuum??

No. You simply will go a different distance based on the energy you ended up with (all of which took a set time to obtain).


Example # 3:

A red car and a blue car both pull up to a supercharger. The blue car takes 60 minutes to fully charge, the red car takes 65 minutes to fully charge. Which car has charged faster?

As it turns out, the blue car is an P85D with a range of 253 miles, or 2.97 miles per KWh. That means in accumulates range at a rate of 253 miles/hr.

The red car is a 90D, with a range of 294 miles or 3.27 miles per kWh. That means it accumulates range at a rate of 271 miles/hr.

Did the red car all of the sudden now charge faster even thought it took longer?


See how confusing mixing up charge rate and subsequent range is?

 

[Troy]

Let's take these two cars as another example:

Model X P100D = 289 miles EPA rated range
Model S 100D = 335 miles EPA rated range

You have arrived at a supercharger and the trip planner is telling you that you need 250 rated miles to skip the next supercharger. OK. So you've decided to add 30 miles buffer and leave this station with 280 rated miles. To what percentage would you need to charge in either car? That's easy to calculate. In the Model X P100D that means 280/289= 96.9%. In the Model S 100D it means 280/335=83.6%. Obviously supercharging the same battery to a lower percentage is going to take less time.

In addition, the Model X P100D driver would not only have to wait longer for his 280 rated miles, but he would also have to pay more. How much more? Tesla's California rate is $0.20 per kWh. The 100 kWh battery has 98.4 kWh usable capacity. Therefore,
adding 280 rated miles to the Model X P100D would cost 98.4 kWh * 280mi/289mi * $0.20/kWh= $19.07,
adding 280 rated miles to the Model S 100D would cost 98.4 kWh * 280mi/335mi * $0.20/kWh= $16.45

So you pay $2.62 more and wait 20 minutes longer if you do the same trip in a Model X P100D instead of a Model S 100D. There will be a similar difference between the Model 3 75D with 300 miles rated range and the Model S 75D with 259 miles rated range.

 

[scaesare]

You've illustrated that total charge time spent is dependent on vehicle efficiency, which does not affect the speed (or rate) of charge, but rather the session duration necessary.

Excellent.

 

[stopcrazypp]

Let's take these two cars as another example:

Model X P100D = 289 miles EPA rated range
Model S 100D = 335 miles EPA rated range

You have arrived at a supercharger and the trip planner is telling you that you need 250 rated miles to skip the next supercharger. OK. So you've decided to add 30 miles buffer and leave this station with 280 rated miles. To what percentage would you need to charge in either car? That's easy to calculate. In the Model X P100D that means 280/289= 96.9%. In the Model S 100D it means 280/335=83.6%. Obviously supercharging the same battery to a lower percentage is going to take less time.

In addition, the Model X P100D driver would not only have to wait longer for his 280 rated miles, but he would also have to pay more. How much more? Tesla's California rate is $0.20 per kWh. The 100 kWh battery has 98.4 kWh usable capacity. Therefore,
adding 280 rated miles to the Model X P100D would cost 98.4 kWh * 280mi/289mi * $0.20/kWh= $19.07,
adding 280 rated miles to the Model S 100D would cost 98.4 kWh * 280mi/335mi * $0.20/kWh= $16.45

So you pay $2.62 more and wait 20 minutes longer if you do the same trip in a Model X P100D instead of a Model S 100D. There will be a similar difference between the Model 3 75D with 300 miles rated range and the Model S 75D with 259 miles rated range.

But his point is you can also easily flip it. Say you drive the X P100D at 65 mph, and the S 100D at 85mph. Then the range might end up the same.

Even if you drive both cars you are comparing at the same speed, the optimal speed range is different for every vehicle. For example even though the Bolt has a drastically higher EPA rating, its optimal speed is much lower given relatively poor aerodynamics, so there is a certain speed where a Model S and Bolt will have exactly the same Wh/mi. So if you use a mph based "charging speed" definition, the Bolt may get a false advantage. Or a closer example: The S 60D at 218 miles vs the X 90D at 257 miles. At higher speeds, I can certainly see the S 60D getting the same range as the X 90D.

There are simply a lot of variables for range (including temperature and elevation change).

 

[slipnslider]

Though I expect Model 3 (base) have manually adjustable seats (considerable weight saving)

I'm glad to see more carmakers are willing to abandon power seats. They really are heavy and expensive and are one more think to break and replace as your car ages. The i3 has manual seats. I hope the M3 does the same.

 

[Reciprocity]

@scaesare
From Wikipedia:

Tesla Powerwall - Wikipedia

6.4 kWh -> 13.5kWh Over 100% increase
Weight however is 20+% higher at 119.9 kg compared to 97 kg.
What I clearly stated was 2x the kWh in a slightly larger and heavier package, so not 2x the energy density since the physical size and volumes are critical in automotive solutions.

Model Technology Price (US$)b Capacity (kWh) Wh per US$ US$ per kWh Power Operating temp. Weight Dimensions (H x W x D) Cycles (during Warranty) US$ per warranted kWh
Powerwall 1 lithium-ion US$3,000 6.4 2.13 469 7 kW peak / 5 kW continuous −4 to 110 °F (−20 to 43 °C) 214 lb (97 kg) 51.3 in × 34 in × 7.2 in (130 cm × 86 cm × 18 cm) 5,000 [9][10]
Powerwall 2 lithium-ion US$5,500a 13.5 2.46a 407a 7 kW peak / 5 kW continuous −4 to 122 °F (−20 to 50 °C) 264.4 lb (119.9 kg) 44 in × 29 in × 5.5 in (112 cm × 74 cm × 14 cm) - ~0.17[18]

Powerpack2 is exactly 2x the capacity at the same dimensions and weight.

I realize that powerwalls and powerpacks are not the same as the automotive packs, but this clearly shows what kinds of improvements they have made going from 18165 to 2170. I am sure that many of the improvements apply to both storage as automotive.

Added link to more detailed specs of PW2:
Powerwall 2 Full Specs Reveal Cheap Storage And Limited Warranty