John O
07-16-2009, 01:47 PM
Check out today's article in Design News: Challenges_Loom_on_Tesla_s_Model_S_Projec (http://www.designnews.com/article/295581-Challenges_Loom_on_Tesla_s_Model_S_Project.php?nid =2321&rid=1100688)
Here's the text:
The electric vehicle's 300-mile range and $49,900 price tag calls for smart engineering and innovation
Charles J. Murray, Senior Technical Editor -- Design News, June 24, 2009
Battery experts said last week Tesla Motors' proposed 300-mile, seven-seat electric vehicle (EV) will serve as a stiff test of EV technology, calling on engineers to employ the best batteries and lightest, strongest materials available.
Model S, which will roll out in 2011, is raising hopes in the electric car community because it offers a huge increase in driving range for a proposed cost of $49,900. Moreover, expectations for the vehicle soared even higher this week as Tesla received $465 million in low-interest loans from the U.S. Dept. of Energy, $365 million of which will be applied to the Model S production engineering and assembly.
Still, the challenge facing Model S engineers appears to be a formidable one. By comparison, Tesla's earlier vehicle, the Roadster, offered 244 miles of range for a $101,500 price tag. Similarly, Mitsubishi Motors' new i-MiEV small electric car will travel 100 miles between charges and cost about $47,000.
Those vast differences might sound imposing, but battery experts said they're not insurmountable.
"It's do-able," said David Swan, president of DHS Engineering, in reference to Tesla's technological goal. "But they're going to have to stretch everything to get there."
Indeed, battery experts said last week that Tesla will need more than the current state-of-the-art lithium-ion battery technology to make the goals work. They suggested that more advancements in battery technology might be needed, along with the application of stronger, lighter-weight body materials to keep the weight down.
"If they are willing to make an aluminum-intensive body or a fiberglass body, and maybe compromise on other high-mass components, they might be able to do it," said Donald Sadoway, the John F. Elliott Professor of Materials Chemistry at MIT. "But it's going to be tough to do that and keep the cost down."
Sadoway said current state-of-the-art lithium battery technology would be hard-pressed to supply enough energy for a big car to go 300 miles on a charge. According to Sadoway's rule of thumb for EVs, an electric sedan would need approximately 1 W-hr/kg of specific energy to go one mile, assuming that the battery comprises about 30 percent of the vehicle's mass. Using that rule, today's best batteries might supply enough energy for a four-door sedan to go 175 miles between charges. An EV-maker could, however, boost that range by packing more batteries on board, therefore losing some valuable volume elsewhere in the car, possibly in the trunk.
"If you're willing to put 40 percent of the mass of the car into the battery, it brings you closer," Sadoway said. "My hunch is that they have a very spiffy, advanced version of lithium-ion combined with an abnormally-high mass fraction of the vehicle in the battery."
Experts acknowledged, however, that a big battery would present a big cost challenge. Swan estimates that the 300-mile Tesla would need at least a 600-lb, 50-60 kW-hr battery, which could significantly raise costs. (An unofficial Design News survey of a group of five battery experts in 2008 indicated that state-of-the-art lithium-ion battery technology would cost between $500 and $1,000 per kW-hr. Making such cost assumptions, a 50 kW-hr battery could cost $25,000 or more.)
Such challenges come into sharper focus when comparing Tesla's proposed vehicle to Mitsubishi Motors' new i-MiEV. The i-MiEV, which rolls out in July, costs $47,000 and offers a 100-mile range. The small four-seater reportedly employs a 16 kW-hr battery, which according to the $500/kW cost estimate, would run only about $8,000.
Still, battery experts said they are optimistic about the Model S, especially if Tesla is ultimately willing to reduce the vehicle's stated range and possibly even subsidize its cost for consumers in the beginning. (However, Tesla's strategies are unknown at this point because the start-up car manufacturer is keeping a tight lid on its plans for the Model S. Responding to e-mail requests from Design News, the company said it is not yet ready for media interviews on the Model S.)
"Even with the 300-mile range, it's not impossible," said Swan, who owns three EVs and has designed batteries for the legendary 254-mph White Lightning electric vehicle during the 1990s. "But all they have to do is say it's a 200-mile vehicle and everything would get a lot easier."
[not shown= pretty picture of sedan]
Here's the text:
The electric vehicle's 300-mile range and $49,900 price tag calls for smart engineering and innovation
Charles J. Murray, Senior Technical Editor -- Design News, June 24, 2009
Battery experts said last week Tesla Motors' proposed 300-mile, seven-seat electric vehicle (EV) will serve as a stiff test of EV technology, calling on engineers to employ the best batteries and lightest, strongest materials available.
Model S, which will roll out in 2011, is raising hopes in the electric car community because it offers a huge increase in driving range for a proposed cost of $49,900. Moreover, expectations for the vehicle soared even higher this week as Tesla received $465 million in low-interest loans from the U.S. Dept. of Energy, $365 million of which will be applied to the Model S production engineering and assembly.
Still, the challenge facing Model S engineers appears to be a formidable one. By comparison, Tesla's earlier vehicle, the Roadster, offered 244 miles of range for a $101,500 price tag. Similarly, Mitsubishi Motors' new i-MiEV small electric car will travel 100 miles between charges and cost about $47,000.
Those vast differences might sound imposing, but battery experts said they're not insurmountable.
"It's do-able," said David Swan, president of DHS Engineering, in reference to Tesla's technological goal. "But they're going to have to stretch everything to get there."
Indeed, battery experts said last week that Tesla will need more than the current state-of-the-art lithium-ion battery technology to make the goals work. They suggested that more advancements in battery technology might be needed, along with the application of stronger, lighter-weight body materials to keep the weight down.
"If they are willing to make an aluminum-intensive body or a fiberglass body, and maybe compromise on other high-mass components, they might be able to do it," said Donald Sadoway, the John F. Elliott Professor of Materials Chemistry at MIT. "But it's going to be tough to do that and keep the cost down."
Sadoway said current state-of-the-art lithium battery technology would be hard-pressed to supply enough energy for a big car to go 300 miles on a charge. According to Sadoway's rule of thumb for EVs, an electric sedan would need approximately 1 W-hr/kg of specific energy to go one mile, assuming that the battery comprises about 30 percent of the vehicle's mass. Using that rule, today's best batteries might supply enough energy for a four-door sedan to go 175 miles between charges. An EV-maker could, however, boost that range by packing more batteries on board, therefore losing some valuable volume elsewhere in the car, possibly in the trunk.
"If you're willing to put 40 percent of the mass of the car into the battery, it brings you closer," Sadoway said. "My hunch is that they have a very spiffy, advanced version of lithium-ion combined with an abnormally-high mass fraction of the vehicle in the battery."
Experts acknowledged, however, that a big battery would present a big cost challenge. Swan estimates that the 300-mile Tesla would need at least a 600-lb, 50-60 kW-hr battery, which could significantly raise costs. (An unofficial Design News survey of a group of five battery experts in 2008 indicated that state-of-the-art lithium-ion battery technology would cost between $500 and $1,000 per kW-hr. Making such cost assumptions, a 50 kW-hr battery could cost $25,000 or more.)
Such challenges come into sharper focus when comparing Tesla's proposed vehicle to Mitsubishi Motors' new i-MiEV. The i-MiEV, which rolls out in July, costs $47,000 and offers a 100-mile range. The small four-seater reportedly employs a 16 kW-hr battery, which according to the $500/kW cost estimate, would run only about $8,000.
Still, battery experts said they are optimistic about the Model S, especially if Tesla is ultimately willing to reduce the vehicle's stated range and possibly even subsidize its cost for consumers in the beginning. (However, Tesla's strategies are unknown at this point because the start-up car manufacturer is keeping a tight lid on its plans for the Model S. Responding to e-mail requests from Design News, the company said it is not yet ready for media interviews on the Model S.)
"Even with the 300-mile range, it's not impossible," said Swan, who owns three EVs and has designed batteries for the legendary 254-mph White Lightning electric vehicle during the 1990s. "But all they have to do is say it's a 200-mile vehicle and everything would get a lot easier."
[not shown= pretty picture of sedan]