# Forums

## Department of Energy's target for EV's in 2020: "Specific Energy Density 250 Wh/kg"; and "Volumetric Energy Density 500 Wh/L"!!!

This information can also be seen in the video: "Electric Car Batteries of the Future (Full)" on YouTube. This video had been oploaded on February 9th, 2013. And there will be about 2 billion vehicles on the roads in 2050. In the end they talk about the "Lithium Air Battery". I am not that educated to understand all that is said in this video. Maybe some of you can see it, and tell us what we should think of this video.

Here is the link to this video:

Timo | February 17, 2013

Panasonic 3.4Ah battery a' 46g 3.4Ah*3.6V/46g = 266Wh/kg.

Odd thing that they want to lower energy density...

Benz | February 18, 2013

@ Timo

In the video (after 22 minutes) they really do mention 250 Wh/kg and 500 Wh/L.

And if your calculation is correct (which I think it is), then it does not make sense. I am puzzled right now!!!

Kleist | February 18, 2013

what he was talking about is the complete battery assembly, not an individual cell... that is not made very clear in the video, but you can guess because he was using a battery assembly for the demo. MS battery assembly is 160W/kg ( highest in EV industry ).

Benz | February 18, 2013

@ Kleist

Thanks man. I knew that there must have been an explantion for it.

With 8% technological development per year, that would mean that after a number of years these targets will be achieved. And that's good.

Brian H | February 18, 2013

About 5 yrs at that rate. But progress is not smooth. It could happen all at once.

Kleist | February 18, 2013

@Benz - this is a good example for many of your questions...
Everyone wants better battery technology - and is waiting for someone to come up with it.. and waiting... and waiting.
But that is not the only option. A second option is to redesign the battery assembly so instead of 160 Wh/kg it gets e.g. 180 Wh/kg using the exact same 266 Wh/kg cells = 12% improvement. And you spend ZERO extra dollars in production, probably you will actually save some money. That is the beauty of production engineering ( I am doing this kind of stuff for 25 years ).
Elon has a deep understanding of the above - watch his Oxford talk.
So while everyone is waiting for better technology - TM is taking what is available today and engineer a smart package. And next package will be a little bit smarter.

jamesamyx | February 18, 2013

Lower energy density because the new technology requires less energy to function. On the surface it sounds contradictory but other factors like energy produced per percentage of GDP in America has steadily decreased over the years because of newer and more efficient devices and technologies. America and other western countries make more money with less electricity. Also a government target is no magic spell. They can set all the standards they want, it does not mean it will happen.

Timo | February 18, 2013

@Kleist; I bet big part of that battery assembly weight comes from the bottom armor. It is structural part of the car, so car floor is actually part of the battery assembly. If you remove the weight what would have to be there anyway then battery mass drops significantly.

That's smart thing in the Tesla cars, they make battery part of the car reducing need for other structures. Unfortunately floor assembly also means that it needs to be protected from hits.

For same reason 60kWh and 40kWh version do not drop battery assembly weight in same ratio as kWh drop would suggest (because that bottom armor has to be there in any case).

This is BTW the reason why I have hard time calculating battery mass in the car total weight: it is part of the car, not separate component, so what is "battery" and what is "rest of the car" is a fuzzy concept here. All I can say that most people overestimate battery weight quite a bit. Car is heavy even without it.

Kleist | February 18, 2013

@Timo - the universal answer of any engineer in any large company is "can't be done because...". My universal response is: "I don't pay you to tell me it can't be done - I can do that myself, I pay you to figure how to do it". Once you break through that mental barrier you will be amazed how creative engineers can be.

It is not that assembly or that armor... find a smarter solution.

Kleist | February 18, 2013

@jamesamyx - my current laptop (many years ago - its old) came with a 40 GB harddrive and the battery lasted 3-4 hrs. I replaced it a newer 500 GB harddrive and now the batty lasts at least 6 hrs. That is exactly the point TM needs to pound on - do more with less.

Timo | February 18, 2013

@Kleist, my point was that they already do what you said, car is heavy, not because of battery but because of everything else in it.

It is not any heavier than any of the competition of same size cars which pretty much proves my point. For example Audi S7 weights 4508 lbs which is only slightly less than Model S.

Considering the physical fact that batteries (without pack) and motor does weight a bit more than traditional ICE the fact that Model S does not weight any more than it does is a proof that Tesla engineers are already building it quite smart. It can't get much better than that unless you start to use exotic and expensive materials and unless batteries themselves get lighter.

Kleist | February 19, 2013

@Timo - MS design is perfect for its size. Future Gen3 has to come down in weight, size, price, etc... how to do it that is the engineering challenge.
My point was that progress most of the times doesn't come from inventions, new technologies, exotic materials, better battery technology, etc... most comes just from smart engineering. Little things like 5% here, 3% there, 12% there... add up and boom your total product is 30% more efficient/better.

Timo | February 19, 2013

There is a error in your thinking there: you get average of these three things (assuming there are no other things), not addition.

It's really hard to increase efficiency when it is already very high. GenIII car will be smaller, but also to reduce cost it will be made from steel, so it does not lose weight quite as much as size difference dictates.

Smaller size does help with air drag and with weight which will increase range, so it might do same range as Model S with less batteries which further save weight and cost.

I wonder how big battery it would require for EV1 to have 300 mile range with Tesla-like design. It is really aerodynamic and it is also very small. If Tesla GenIII "affordable car" would have anywhere near that kind of size and aerodynamics it could have very large range with quite small battery pack.

Brian H | February 20, 2013

@Timo
+1

That's the essence of it. No exotic advances required.