The recent introduction of Tesla Motors' Model S electric vehicle raises an important question: How is Tesla able to get a 300-mile range when other EVs are lingering around 100? The answer is only partially obvious. The Model S's well-known and oft-repeated 300-mile range applies only to the versions with a 85kWh battery.
Even in the world of electric cars, that's a massive battery. Consider that the series hybrid Chevy Volt uses a 16kWh battery and the all-electric Nissan Leaf, a 24kWh battery. As we mentioned a few months ago, 85kWh is big, even when compared to the Rolls Royce 102EX experimental electric (1,400 lb and 71kWh) and BYD e6 (72kWh).
Still, Tesla is doing more than just dropping a huge battery into its Model S cars. The company is squeezing every bit of available juice out of its vehicles. While the 85kWh unit hits a 300-mile range (according to EPA measurement methodology), the smaller batteries do well, too. The Model S's 60kWh battery gets 230 miles of range, while the 40kWh version hits 160 miles. In terms of miles per kilowatt-hour, that's better than the Volt or the Leaf. It's also competitive with the Tesla Roadster -- a $109,000 two-seater built in 2008 that weighs 1,900 lb less than the Model S.
Tesla's Model S offers an all-electric range of as much as 300 miles. (Source: Tesla Motors)
"Even though the Model S is a much larger and heavier car than [the] Roadster with ridiculously more cargo capacity, the total battery energy consumption on the highway is only about 10 percent more than the Roadster," wrote Tesla CEO Elon Musk and CTO JB Straubel in a recent blog. In their blog, Musk and Straubel point to a graph showing that the Model S, traveling at a constant speed of 20 mph, can get more than 450 miles on a charge. From 50 mph to 70 mph at constant speed, the vehicle gets between 240 and 335 miles of range.
Amidst the tumult of the recent Model S introduction, Tesla hasn't yet detailed how its engineers are able to do that. When we talked to Straubel in 2009, he identified a multitude of little features that when taken together, give the company more miles per kilowatt-hour than competitors. Straubel cited innovations in cooling, aerodynamics, and rolling resistance. He also described how specialized brake calipers and the changeover from a two-speed to a single-speed gearbox helped boost the Roadster's all-electric range.
Still, battery size is the biggest factor in Tesla's all-electric range. And that, of course, translates to high cost. Tesla hasn't yet unveiled the price tag for replacing the Model S batteries. On its Website, the company said it expects the battery to retain 70 percent of its capacity over seven years or 100,000 miles. But it added that "it would be impossible to forecast the cost of future battery replacements." Earlier this year, however, it was revealed that Tesla quoted a $40,000 replacement price for a customer who accidently fried his Roadster battery.
For car buyers, the bottom line is that the Model S's large size and high battery cost put it in a different vehicle segment than its EV predecessors. The base Model S is $57,000, before the $7,500 federal rebate. Its high-end brethren, the Signature Performance edition, is $105,000, before the rebate. "The Model S is upscale, so it's going to go head to head with BMWs and Mercedes," said Dave Hurst, senior analyst for Pike Research. "Everyone will be watching to see how it does in that class."
It doesn't surprise me that Tesla's gurus won't talk about how they're "squeezing all the extra juice" out of their battery options. Isn't that a key differentiator and competitive edge for EV companies? Why should they give away their secrets if they're able to come up with a design and a chemistry mix that gives their cars an edge? More power to them--and those that can afford the cars!
Beth, you are right that battery technology is the crux of the matter with electric vehicles. They were more forthcoming with the roadster because it was a new thing and there was not much competition. Of course that has changed. With the roadster, the battery pack weighs 900 pounds, as I recall. It reportedly gives a range of up to 400 miles (I am not sure under what conditions). The Model S has a completely different form factor, and I expect a whole different technology. This is an area that is progressing fast.
It's clear to me. It's the little things like lower weight tires, lubes, aero, fewer gears, brake retract springs, etc that can easily double the range of a given battery.
As the battery pack gets larger it's less stressed so can put out more of it's capacity per unit of vehicle weight.
In lead battery EV's going from 25% battery/vehicle weight range is about 30 miles but with 50% battery weight range hits 100 miles as an example.
In fact the about plus 50% lead battery weight is how I'll get 100+ mile range along with the above 'tricks'. I keep the battery weight, cost low by having the EV without battery only weighing 550 lbs mostly by using a composite body/chassis that weighs 235lbs.
As I've been saying it's not so much the battery but the vehicle it's put in.
Beth: yes, apparently, they are finding people who can afford it. The top-of-the-line Signature Series (which costs up to $104,500) was already sold out for 2012 in early June.
Thanks, They certainly didn't reduce weight much to gain range! But it is a $100k Luxury car.
I really can't see why most EV's need over 100 mile range when for 130lbs one can have a 35kw Lotus Range extender IIRC and get unlimited range for many $1000's less. I'm doing a 4.5kw version that weighs 40lbs in mine.
I'm all for the eff of EV drive but moderation is the smart choice.
Had they went composite body/chassis both the production line start up costs would be 1/3 and unit cost by 40% for the same performance and more quiet, stiff.
With this type of range, it would seem the EV could move beyond a second car and become a primary car. Another question, Chuck. Does passanger weight and load have much of a factor in affecting speed or range?
Tesla is no more knowledgeable than any other electric car automaker (Nissan, GM, etc) about how to get the most miles perkWhr. For electrics, which benefit from regen braking, weight is not that important, sans very hilly country, which was studiously avoided by Tesla in claiming 300 miles of range. They also did not run the heater or AC, drove at a constant speed and never opened the windows or stopped or started. Aero is important,as GM found out while developing/testing their Volt, also tire rolling resistance (use skinny , highly inflated tires). That's about it. Nothing else makes any significant diference. Tesla is exaggerating greatly any small increments they got from tweaking motor rpms, etc. That battey is off the shelf-for the 300 (ho,ho) mile range pack it contains 7600 Panasonic 3100mAH 18650NCR laptops. They are retailing for around $14, or over $106,000 for the pack.Tesla is estimated to be charging over $45,000 to their customers, which is probably about what they are buying them for. The entire battery system probably weighs close to 1000 pounds. They have a very selective warranty (they don't cover total discharge -fried battery pack) of 8 years or 150,000 miles (unlikely with capacity losses and recharging cycles of around 500).
The battery is obviously the car's fatal flaw. Imagine the resale value after 7 or 8 years, near the end of the battery's lifespan. Battery capacity losses are not covered by warranty, and Tesla avoids saying much of anything about those batteries, since anything they say will likely kill sales. If you buy a Model S avoid the "300 mile pack." Get the smallest battery pack option and wait for decent batteries (you'll need to own two cars, of course).
It doesn't surprise me that there are takers for this, even at these outrageously high prices. Consider luxury vehicle + politically correct purchase + love of technology and you've got a perfect car buy for a very select few. The fact that they sold out for that particular version just shows they didn't anticipate how big the very targeted market would be.
I have to say I'm largely in the same camp as ramon here. They appear to have thrown money and batt size at this and got a longer range (Waiting to see what some independant testing gets on that). They may indeed have a viable luxury niche, but this is a long way from making mainstream EV a popular proposition.
Jerry Dycus
You keep mentioning the vehicle(s) you build/are developing. Do you have a website or such. I've long had an interest in minimalist vehicles and would be interested in seeing your ideas.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 3
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
25 
