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Battery weight

Just curious. A number of friends have played devils advocate concerning the added weight the battery must have. What's the weight of the engine for a 5 series or an A6?

I have no doubt that all you folks are very smart, but get a grip and reread the disrespectful crap you have written lately! Might I suggest that you all take a break from this thread and return when you can post like mature adults.

Larry

As much as I enjoy flamefests...

Has anyone done the calculation on how much faster Model S will be as it sheds weight? I'm thinking that the 160 will be much lighter than the 300 and thus faster off the line. Or will the motor be different or governed less to account for the difference?

I don't think to motor will be different but you could probably have less power from the battery. Hard to compute (without precise data) which one takes the crown.

Unfortunately the 160 will not be very much lighter and it will have less power available. The battery engineer at the factory event confirmed that the 160 will not be able to go faster than the 300. In fact although he did not say so, he hinted that the 300 might be needed to get maximal acceleration.

I bet if you took the skateboard, slapped on a steering wheel and a lawnchair, you would get maximal acceleration. :-D

@William13
"The battery engineer at the factory event confirmed that the 160 will not be able to go faster than the 300."

Interesting.

I'd love to see some written (internet counts) commentary from Tesla folks like this engineer. I'm curious from the technical side, not from the buyer decision side.

I doubt anyone outside of Tesla knows. However, I suspect there would be current (ampere) limitations on the smaller battery packs.

TESLA has said the 160 and 230 are the same technology batteries and the 300 is a new material set. So it will be interesting to find out if the 300 will weigh just slightly more or significantly more.

Just for fun.....
If we assume a battery pack similar to the roadster configuration of 6831 cells in 99S69P and a 306HP engine with 85% converter efficiency we get some intersting results. Using 300Wh per mile we obtain the folowing pack sizes. 160 pack > 54kWh ; 230 pack > 69kWH ; 300 pack > 90kWH. This leads to the conclusion that the 160 pack is using 2.14Ah average batteries and they are being pushed at a 4.75C rate. The 230 pack is using 2.73Ah batteries and being pushed at 3.75C rate. Finally the 300 pack is using 3.56 Ah average batteries being pushed at 2.85 C rate.

While these C rates are very high for normal 18650s, keep in mind that these are designed by Panasonic for this from day one. I don't see any reason why all three pack sized vehicles wouldn't have nearly identical performance unless the 300 is significantly heavier. The 2.1 and 2.7 AH batteries are indeed in the normal distribution of high rate Li-ion 18650 batteries. (7 years ago we were making them in the 2.0 to 2.5Ah range....)

Can't wait to get some facts from TESLA on their real numbers instead of guessing! Hopefully next year when they get closer to prodcution we'll get some hard answers.

BruceR, there is a thread that already discussed this in much more detail. The posts there are as speculative as yours is, but nonetheless may be interesting to read:
http://www.teslamotors.com/forum/forums/battery-weight-vs-acceleration-time

@BruceR:

Thank you for a very informative and illuminating discussion and presentation of performance numbers associated with the types of batteries anticipated to be used in the Tesla vehicles. One set of numbers towards the end of the comments especially caught my attention. In particular,
" The 2.1 and 2.7 AH batteries are indeed in the normal distribution of high rate Li-ion 18650 batteries. (7 years ago we were making them in the 2.0 to 2.5Ah range....) "

So, according to this, it took 7 years for the battery capacity to increase by 5% . Assuming a comparable percentage increase in capacity over 7 year periods, we can calculate that it would take slightly more than 99 years to double capacity. This type of number should significantly dampen any belief that Tesla batteries will have double, triple, or higher capacities in only five or ten years.

If you're talking about li-ion tech, you're right. Li-ion is probably close to the top of the S curve. A new technology will take over from it just like NiMh took over from lead acid and li-ion took over from NiMh.

If you're talking new technology for transportation check this out.

http://www.youtube.com/watch?feature=player_embedded&v=Ws6AAhTw7RA

Calling Luke Skywalker, your landspeeder is ready!

Yeah, where's my flying car dagnabit!

@Mycroft

Something about "flying car" and "dangabit" in the same sentence seems wrong to me.

It's like calling EVs groovy.

Note that the sport version uses the same battery pack as the standard 300 version but a more powerful inverter. I don't remember if anyone said anything about the motor being changed. This would indicate that the rate limit for acceleration would be the inverter, the batteries, or the power management software.

@Volker.Berlin - Thanks for the link. Interesting reading, but as you said just as speculative as my own logic. Lots of people quoting rough numbers from 2009 and drawing precise conclusions. (Like 8000 batteries in the S and 6000 in the Roadster. It is a fact that the roadster actually uses 6831 for examaple. So what will Model S use exactly???) As I said, can't wait till next year when we get real data!

@Zelaza - Huh? How can you pick and choose the information presented to make your points. Did you miss the 3.56Ah cell average I came up with for the 300Ah pack? This is a ~50% improvement from the basic 18650s of 7 years ago......
(And is entirely consistant with Panasonic's 2012 production of 3.4Ah minimum capacity 18650 cells.)

http://www.ecofriendlymag.com/sustainable-transporation-and-alternative-...

@BruceR:

I did not intend to pick and choose data to make a point. As I indicated, what caught my eye was the only data provided that indicated that after 7 years some battery type improved by 5%. None of the other battery performance data provided had a development time so one could not estimate how long it took for significant performance improvement. I had no intention of making any such calculation; the data, as it was presented, just said "analyze me." My purpose was not to get a definitive result, but to show a basis to encourage caution before making exaggerated assertions about how quickly batteries would become great.

After checking the site you suggested, I did become confused about some of the battery types you concluded would be used in the various battery packs. The performance table at the site is two years old and (two years ago) the least capable battery there had a capacity of 2.9Ah. So using 2.14Ah and 2.73Ah would not seem likely, unless you think that Tesla might use inferior batteries in the 160 and 230 mile battery packs. It would seem that 3.4AH batteries should be used in your analysis and later, for 2013, perhaps 4.0 Ah batteries. What I would assume is that the best available battery (within price and size constraints) would be used in all the battery packs. Or is that unreasonable?

@Zelaza, "It would seem that 3.4AH batteries should be used in your analysis and later, for 2013, perhaps 4.0 Ah batteries. What I would assume is that the best available battery (within price and size constraints) would be used in all the battery packs. Or is that unreasonable?"

I would think that too. At first someone at Tesla told that there would be different battery chemistries with 230 mile battery and 300 mile battery pack, but because they make 300 mile packs first I don't see any reason to use inferior batteries in 230 mile, unless they just are plain cheaper (same amount of cheaper batteries?). If price for kWh is similar then I would also assume they use one battery type for all battery pack sizes.

Zalaza, please check the Panasonic site. Tesla will use Panasonic cells. Also note that we are talking about rechargeable Li-ion cell. The 300 mile will be using either the 3.1 or 3.4 Ah at 3.6V nominal batteries. The 2.9 and 3.1 Ah started to ship last year in small quantities. Tesla may have an early version of the 3.4 Ah. Panasonic has not said much about the 4.0 Ah. It weighs a fair amount more than the others.

Of course Tesla may have a proprietary version due to its active cooling. Elon had always said prior to announcing that the 300 mile version would be available at launch that Tesla would only use tried and true cells that were not the latest and greatest to make sure that the cells would hold up. We thus ass u me d that the most advanced cells would be the 3.1 Ah.

Panasonic had announced the 3.4 and 4.0 Ah cells around this time last year but still has not offered them for sale.

That being said, I look forward to a car with the 3.4 cells that give "85 kWh." and 300 to 320 EPA miles.

Lots of great clues given out in interviews today. No facts, but I find this article by Plugincar tantalizing about the weight issue

Because the batteries can be removed quickly, and because Tesla will offer three separate packs for the Model S with 160-, 230- and 300-mile range, it gives rise to speculation that customers could “trade up” after buying the car. Straubel admits this is theoretically possible, since all three packs slot into the same space, but both Straubel and Musk downplay it as an option—in part because the 300-mile pack is heavier and requires some suspension adjustments.

Full article :
http://www.plugincars.com/elon-musk-cool-confidence-about-teslas-future-...

Straubel admits this is theoretically possible, since all three packs slot into the same space, but both Straubel and Musk downplay it as an option—in part because the 300-mile pack is heavier and requires some suspension adjustments. (as quoted by BruceR)

Maybe that's the key to understanding why Tesla is pushing the air suspension option even though air suspension is expensive and more problem prone than classic spring suspension and definitely not one of Tesla's core competences. If there are substantial weight differences between the different battery packs, air suspension may be a prerequisite for swapping in a different range battery.

I don't think the air suspension has any relevance to the weight of battery or car. The weight differences are minor between the packs for standard sedans. One or two passengers make more difference. This is however a sports sedan that they want to be world class. The suspension is tweaked for most cars to adjust for weight.

I was told two and a half years ago when making my deposit that the signature would likely have a "tunable" suspension. To make more money I expect this as an option on the standard model.

According to one of the Tesla employees at the Bellevue store event this weekend, the car will weigh the same regardless of which battery pack you get. She said that weights will be added to the cars with the smaller packs. She may be completely off base as many of the employees there seemed to know only the basics about the car. I asked if it was to ensure the same weight distribution between cars and she said yes.

I also asked whether someone could upgrade from a 160 mile pack to a 300 mile pack and she said yes. I'd love to know is she had actual information or if she was just making it up as she went to sound knowledgeable.

On that topic, I also asked about ground clearance to another employee because I have a steep driveway that low cars bottom out on. After checking with someone else, she told me the ground clearance is ten inches, but the optional air suspension would likely have controls through the dash to raise it an undetermined amount on demand. What she said sounds good for my situations, but elsewhere, I've seen 6 inches ground clearance.

10" sounds way too much, that's an off-road vehicle ground clearance, and Model S is definitely not off-road vehicle. Maybe she was talking about Model X?

Yes, she's a bit off. Ground clearance unloaded is supposed to be 6". But with the air suspension option, you'll probably be able to raise the clearance manually via the touch screen.

And it makes no sense to add additional weight to the smaller packs.

Ground clearance has been the subject of discussions in many of the different forums, a very legitimate concern. Performance in various road\weather conditions(snow), practicality in terms of entering\exiting\parking (curb clearance) can all be addressed with the adjustable air suspension. As I mentioned in previous threads, the Audi Allroad has this standard feature giving it more clearance then a BMW X5 when on the highest setting, great option to consider!

They're going to have LOTS of "great options" to consider. :D

@Mycroft - Precisely. If money were no factor I would definitely get a fully loaded Signature, but sadly I will have a 160 with maybe one or 2 features depending on pricing (fingers crossed).

IN an electric car, which recovers a very large portion of its kinetic energy via regen, total vehicle weight is not anywhere near as important as it is for a non-regen vehicle. GM noticed and remarked on this when they began testing their Volt and trying to achieve their target electric range.
To compare electric and ICE vehicles - total up the weights of their respective drivetrains (including all required accesssory parts). For the electric, this would be the battery, the controller,
the motor and reduction gearbox. For the ICE total the weight of the entire engine,transmission, driveshaft, fuel system including gas tank and typical weight of contained gasoline,exhaust system, and all sensors and electrical parts required for the engine to operate.
Disregard cooling systems and AC since both cars need them.


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