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I have a 60kWh car but it's so new that I am having problems keeping my consumption below 400 wh/mile. I can verify that it's wicked fast though!

Hans - on a "normal" trip, what kind of wh/mile are you seeing? Are you in cold or temperate climate?

I'm not sure what a "normal" trip is but I would be happy to drive a set speed on cruise control for a set distance and let you know what the avg consumption is over that distance and terrain. I am in the San Francisco Bay area so a temperate climate. My avg consumption over the last 300 miles is 370 kW/mile but that is definitely NOT normal driving for most people.

Any info would be great. It doesn't have to be cruise control but just standard driving that doesn't include gunning it at every opportunity. Although that is obviously the most fun thing to do.

Just pick an ordinary, old-fashioned car, and pace it. ;p

I have started capturing w/mile
https://docs.google.com/spreadsheet/viewform?om=true&richtext=false&form...

Results can be seen at
https://docs.google.com/spreadsheet/lv?key=0AhXq4QSAykf4dHc3Y2JwSmlpMWdF...

All entries are currently from 85s with avg of 329 w/mile

Response to shoendp. Reasonable estimate for Li-ion battery energy density is 150 Wh/Kg. so that means then the 85 kwh battery will weigh about 570 kg. The 60 kwh battery would weigh 402 Kg. so the weight difference is about 167 Kg (367 lbs). I am not sure the Wh/mile numbers you estimate can be explained by just the weight difference. So my gut tells me it has more to do with driving style than battery type.

Plus, not only does the 60kwh have less weight, it also has less battery to regulate the temperature of, which reduces electricity usage.

@crttnarayan/@archibaldcrane - have you seen any info from TM about this that supports the idea that the 60kWh car is lighter? All the informal info I've heard from TM and seen on the forum says that the 85 and 60 batteries are different chemistries, have different energy densities, and approx the same number of cells, hence the same weight.

The Model S specs page only shows one curb weight, not different weights for different models.

I talked to the Tesla Ownership team today and they said that Tesla is now publicly stating that the 60kWh version is lighter than the 85kWh version. However, they still will not give specific weights. They also said that the configuration of the 40kWh was not complete yet, but that it would be lighter than the 60kWh. I did not write down the name of the guy I talked with, but he seemed very confident in the weights and did not waffle at all when I questioned him.

@crttnarayan, Tesla is using Panasonic NCR18650a for 85kWh Model S, about 8000 of those gives you 90kWh. Each cell weights 46g. That gives batteries alone 368kg. Energy density for those batteries is about 243Wh/kg, so you are off by about 90Wh.

Battery casing doesn't change between models, but wiring does. I have no idea how much that adds / cell, and also how they change the cooling for different models is unknown, but anyway, weight difference should not be as big as you estimate it to be.

@schoendp, 40kWh have to be quite a lot lighter because 160/300 > 40/85 and only thing explaining that increase in range/kWh for 40kWh model is that weight difference.

Same actually applies to 60 and 85 too: 230/300~=0.77, 60/85=0.70.

@Timo, while the energy density of the cell is close to 250 Wh/Kg the energy density of the battery pack is substantially lower because of how the cells are independentally housed. The 8000 cells are grouped into small number of cells which are clustered into battery packs. Several of the battery packs are packed into the battery housing. While the battery housing or casing is nominally the same for all the models what is different is the number of battery packs they have for the different models. These battery packs have energy densities closer to 150 Wh/Kg. For crash test safety reasons the housing is the same and the packs are distributed so the weight distribution is uniform. There will be small differences in housing to permit even distribution of battery packs, which is why you cannot upgrade the battery after you buy the car. This was how it was explained to me when I took a detailed tour of their R&D test floor in their Palo Alto lab.

The biggest difference I've experienced so far (I don't drive long distances) is the $10k. Glad I got the 60.

I have a hard time believing that those "packs" would be so drastically heavier than cells in them.

I would estimate closer to 200Wh/kg / "pack" ("cluster" might be better word). Or did they say to you that each cluster has 150Wh/kg energy density? Was that with or without cooling? Because I believe that plays quite a big role in the final weight of the entire pack (water is heavy), and I have no idea how that is made, does is follow the same ratio as cell number in the pack?

Take a look at some of the pictures posted on the MyNissan Leaf of the internals of a Tesla battery pack:
http://www.mynissanleaf.com/viewtopic.php?f=10&t=2429&start=1080#p261871

@murraypetera - sorry, the 3235 entries in your spreadsheet should be 85kWh + air + 19" wheels