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Why Aluminum?

Why Aluminum?

Hey guys! Thanks to everyone who gave me feedback for my previous thread. It helped me a lot. I am writing this thread in a form of a question. Can somebody give me a very detailed explanation on why Tesla chose aluminum for Model S and why it is the next-generation material for the automobile industry. Also, can someone tell me why it is better than steel and other materials and how. Thanks so much!

AirForce462 | 19. august 2013

The short answer is weight savings. The majority of this car's weight lies in the batteries, and the car weighs in just under 5000lbs. If the vehicle were made with a conventional steel body and frame you could easily add several hundred more pounds, which would decrease the performance and range. With sufficient engineering the aluminum is just as strong in an accident, while being much lighter. I am not an engineer but I believe that this is the gist of the reasoning. When I worked at Tesla I worked in the battery module line and after that I built and tested superchargers, however I am not an expert on the finer points of the car.

stevenmaifert | 19. august 2013

This pretty much says it all: http://www.teslamotors.com/models/features#/safety Aluminum to save weight, reinforced steel where it counts.

docdac | 19. august 2013

Aluminum does not corrode as easily (i.e. no rust), so it should hold up better in that regard.

jbunn | 19. august 2013

Steel is about three times heavier per volume than aluminum. The weight difference in a car body and chassis is substantial.

jq5073 | 19. august 2013

The same reason aluminum is used in Festivus Poles.

shop | 19. august 2013

And the reason aluminum isn't used in all cars is cost.

archibaldcrane | 19. august 2013

The other option would be carbon fiber, but that's even more expensive.

mrspaghetti | 19. august 2013

If someone ever makes a time machine out of a Model S (a la "Back To The Future"), the car would be worth a fortune. As Brian H has stated previously, aluminum used to be worth more per unit weight than gold. Now we make whole cars out of the stuff and wrap our leftovers in it.

How the world changes from one generation to the next, eh?

Cattledog | 19. august 2013

Jason_Augustus - If you ever want to share insights that you are able to share (not looking for you to violate an NDA), please do.

Energy_Freedom | 19. august 2013

Good info.

Is there any hope of aluminum going down in costs if for example more production starts happening? Alternately, is there any other lightweight strong body material showing promise?

soma | 19. august 2013

I don't think there is much room for aluminum to go down in price aside from macroeconomic demand. It's one of the top commodities out there. Tesla is a tiny player.

michael1800 | 19. august 2013

Going back in time in a Tesla would be horrible! 120V 20A charging if you're lucky!

Brian H | 19. august 2013

Zero-g refined iron has some amazing properties. ;)

johnny electric | 19. august 2013

Ah ha.......you have just figured out Space X's real agenda......

omarsultan.ca.us | 19. august 2013

@soma: this is apparently a fair amount of manipulation with AL pricing--this was being reportedly widely a few weeks ago: http://www.bloomberg.com/news/2013-08-12/u-s-regulator-subpoenas-banks-o...

Jolanda | 20. august 2013

BMW is on the right track with Carbon Fiber Reinforced Plastic (CRP). This is a way to use the advantages of Carbon fiber without the price problem.

We will find materials that are lighter and stronger than these. But it will take time. Till then aluminium is a great way to loose some weight at minimal cost.

The best way to reduce weight in an EV is for sure the battery.

Nexxus | 20. august 2013

The use of aluminum isn't just for the weight savings. Using aluminum panels and structural members allows the "crumple" zones to expend more energy from the collision to keep it (said energy) from being transferred to the passengers. This also keeps the occupants from seeing more than a few G's going from whatever speed they are traveling and coming to a complete stop, because the Model S dissipates the energy through the crumple zones.

Think of it like the indy or stock cars, when they wreck, the cage surrounding the driver pretty much stays intact while the rest of the car crumples and parts go flying off taking all the energy of the collision with them.

Nexxus | 20. august 2013

Sorry, meant to add that steel is not as forgiving as aluminum is the crumple zones. That's what makes it a better energy dissipation material.

DigitalSavant | 20. august 2013

@michael1800 - you'd have to take it to the future first, to get it fitted with Nikola Tesla's unrealized invention, the "Self-acting Engine"... or maybe just a Mr. Fusion.

Bubba2000 | 20. august 2013

Tesla made the right choice with Al body reinforced with alloy steel. I think that they can still take advantage of the wide variety of specialized alloyed Al to reduce weight. That would include Al-6061 Grades, etc. Stronger steel alloys - even Titanium for critical parts could used. Model S could loose 1,000 lbs while keeping the structural integrity, safety intact. It is a cost/benefit issue.

Elon has access to SpaceX engineers that are experts in this area. Over time we could see gradual improvements.

ny3ranger | 07. august 2015

I read that alfa romeo 4c uses something that is even lighter then aluminum but same or better strength. So, hopefully, the car gets lighter in the future. I don't think that the battery weight will change much. We seem to just need more range, therefore, it's at least the same weight in battery (if not more). If you can get the car to where ICE car weighs then you are instantly going to see some more range and faster acceleration.

Basem | 07. august 2015

Aluminum Mass number is: 27
Steel Mass number is ~ 58+

I recall that in the "how its made" video the current chassis wight (using AL), is ~ 850 lb.

Using steel will means that the chassis weight as follows: 850 * 58 / 27 = 1825 lb.

I do not know the exact relation between range and weight but this mean a lot less range ....

It is that simple.

FelixMendeldog | 08. august 2015

In addition to aluminum’s many excellent characteristics others mentioned above, aluminum is easily recycled. Aluminum is quite abundant in Earth’s crust (unlike gold); but is it more difficult/costly to extract than iron (which is the largest ‘ingredient’ in steel.) But as more aluminum is extracted (and since it is easily recycled) there is indeed room for the price to decrease.

georgehawley.fl.us | 08. august 2015

Even with Aluminum the Model S is way too heavy to completely replace comparable ICE cars because of the road trip range/transit time issues. These won't be resolved for many years of battery development and until carbon fiber pricing is competitive. Meanwhile, Tesla will sell many great cars to the rest of us who don't need to average 65+ mph on road trips.

Red Sage ca us | 08. august 2015

Actually, the How It's Made episode for Model S and the MegaFactories episode about Fremont stated that the aluminum 'body in white' for Model S weighed around 400 lbs. A shift to carbon fiber or other material would barely reduce its weight at all, but would certainly introduce issues with crash safety, as compared to the current setup.

It seems that both Elon Musk and JB Straubel feel that eventual improvements in battery technology will allow ~85 kWh of energy to be stored in a considerably lighter array of battery cells. Thus, if the same amount of energy were stored in a battery pack that weighed half as much, or one-quarter as much as in 2012, you would gain either more range, or a higher percentage of gross vehicle weight rating for passengers and cargo.

That would likely result in a car whose curb weight at this size was much less than its contemporary ICE counterparts from AUDI, BMW, Mercedes-Benz, and Porsche. Well before a battery pack of ~120 kWh or better weighs under 200 lbs ICE vehicles will have been shown to be fully outclassed by electric vehicles.

Basem | 08. august 2015

Thanks Red, for the correction about the 'Body in White' weight.

Roamer@AZ USA | 08. august 2015

@georgehawley, I haven't changed how I road trip. I probably have 30,000 road trip miles and drive the same as I did in my ICE. Not sure why you think you are highway speed limited. Plan your charge stops and just drive normally. Once in a while you may need to slow a little to make a long charger stop run. With each SC opening the ability to just drive normally improves.

prp | 08. august 2015

@red, a carbon fibre shell will be significantly stronger and safer than an aluminium shell. Will cost significantly more too.

Pollux | 08. august 2015

Looking at @sk1656's original posting, I have the feeling that you folks collectively just wrote his/her term paper or some other class assignment.

Alan

oragne lovre | 08. august 2015

@Pollux

:):):)

prp | 08. august 2015

Hope we all get an A+

Red Sage ca us | 08. august 2015

Carbon fiber bodywork/life cells are designed to compress, then shatter upon impact. Aluminum bodies/frames are designed to deflect and deform. If the exact same aluminum frame and body panel designs for Model S were made of carbon fiber instead, it would not perform as well in crash tests.

The entire frame and all the bodywork would have to be fully redesigned for carbon fiber construction. So it would be bulkier, intruding further into the passenger compartment, diminishing cargo volume, and reducing visibility.

Even if it then passed crash tests, it would not do as well as the aluminum design. Sure, you'd survive. But you might not walk away.

EdwardG.NO2CO2 | 08. august 2015

@Red would you agree that repairs (even minor) would also be more expensive than Aluminum?

prp | 08. august 2015

@red, notice that F1 and indy cars are no longer aluminium, rather all carbon fibre. those cars cannot meet the crash test criteria any other way. Further the latest jets like the boing 787 are now carbon fibre rather than aluminium, as are the latest ferrari and mclaren cars.
It costs a lot more though, and isnt repairable. Parts have to be replaced. You wont ever get another dent though.

Red Sage ca us | 08. august 2015

Expensive?

Yup.

prp | 08. august 2015

Nice graphic! Interesting that all the leading edges are aluminium.

mclary | 08. august 2015

Who cares?

Silly question.

Flagged!!!

Tropopause | 08. august 2015

prp, the leading edges are aluminum because that's where the hot bleed-air is ducted to remove ice build-up in flight. Bleed-air is capable of starting fires with materials that can't withstand heat.

prp | 09. august 2015

Thats really neat! It's interesting that such a fundamental requirement on a very small area consumes 20% of the plane's mass. Just shows the relative mass of the various materials.

Bighorn | 09. august 2015

As a young South Africsn, Elon had a penchant for saying "aluminium" .

Red Sage ca us | 10. august 2015

One thing to keep in mind: No government entity requires 'high speed' crash testing of passenger vehicles for use on public roads. Most official tests are run at no more that 40 MPH. The idea being, that if you can't survive a crash at that speed, it doesn't matter what happens at higher speeds.

But an automotive television show called 'FIFTH GEAR' decided to find out what happens in a 120 MPH frontal crash test performed on a Ford Focus. Yes -- at three times the normal testing speed. The result was not pretty.

There have been crashes of the Tesla Model S at speeds approaching or exceeding 100 MPH wherein the occupants walked, or ran, away afterward.

DTsea | 10. august 2015

There is no bleed air on 787. It uses electrical resistance heat for anti ice.

Much of the aluminum is internal... brackets, fittings, etc.

georgehawley.fl.us | 10. august 2015

@Roamer: right for you but not for folks who might be called "iron butts" and want to average 65 mph and up on road trips. Model S won't do that because of charging time. Part of the answer is a battery pack with something like 150 kWh of capacity that you run 300 miles from about 75 kWh down to 10kwh so that recharging rate is minimized by only recharging a little more than half full. Part of the answer is SCs that operate at maybe 150 kW to increase the charge rate subject to Li-ion tolerance. Part of the answer is a dramatically lighter car (think ~3200 pound Model S) to reduce the rolling friction since air friction has already been reduced with an industry leading drag coefficient of .24. I say carbon fiber (take a look at the BMW i3 construction.) Carbon fiber saves about 30% of the weight of Aluminum I think. I believe the hardest part is the batteries because there is no obvious road map today to a 65-70% improvement in energy density that I know of.

I have run the numbers. Hard for a BEV; easy for a Chevy Cruz for example.

The first BEV to rival the road trip efficiency of ICEVs is likely to be the next generation Tesla Roadster that, I think, will use a lot of carbon fiber or equivalent.

sp_tesla | 29. januar 2016

What is the actual weight saving compare to steel?

RedShift | 29. januar 2016

Sp_tesla,

Read the thread. It gives you the weight savings for the 'body in white' (chassis) weight savings.

sp_tesla | 29. januar 2016

RedShift | JANUARY 29, 2016

Sound like my wife: you need to read everything because that what I was trained to do, will not give you the easy answer, Errrr