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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!

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.

This pretty much says it all: Aluminum to save weight, reinforced steel where it counts.

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

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

The same reason aluminum is used in Festivus Poles.

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

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

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?

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.

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?

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.

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

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

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

@soma: this is apparently a fair amount of manipulation with AL pricing--this was being reportedly widely a few weeks ago:

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.

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.

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.

@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.

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.

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.

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.

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.

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.

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.

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

@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.

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

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.