Like most other electronic devices, the success of Tesla Motors, Inc.’s automobiles hinges greatly on the batteries that power the vehicles. Electric cars have existed for decades, but only recently has the technology been able to sustain longer charges.
Palo Alto-based electric-car manufacturer Tesla is working alongside Japanese electronics giant Panasonic Corporation to develop battery technologies that extend the 245-mile-per-charge range of Tesla's Roadster model. The Model S, which the company plans to debut next year, may travel as far as 300 miles per charge.
Consumer confidence in electric vehicles is often hurt by the limitations of the car batteries, and many close to the industry understand that there are a lot of misconceptions when it comes to the battery life issue.
“One of the reasons people hesitate to get an electric car is this perception that it's going to run out of juice somewhere and leave them stranded by the side of the road,” said Jerry Pohorsky, president of the Silicon Valley chapter of the Electric Auto Association. “To a certain extent, that is a real consideration. You can drive these things to the point where they won't go any more.”
Tesla’s batteries are the most powerful among commercially available electric cars. Further innovation in the quality of electric vehicle batteries has the potential to make the electric vehicle, or EV, category more viable in the marketplace.
“Battery development is the driving force behind the EV movement,” said Tesla spokeswoman Camille Ricketts.
Tesla supplies electric vehicle components to other automotive companies, including Toyota Motor Corp. and Daimler AG.
The Tesla Roadster model’s design was inspired by the Lotus Elise, a gas-powered sports car that averages 210 miles on a single tank. Typically, cars can travel between 300 and 400 miles on a tank of gas.
Hypothetically, Bay Area drivers of the Model S will be able to drive as far away as Reno, Nev., or Santa Barbara on a single charge — something that would have been considered science fiction when the first generation of production electric vehicles was introduced in the mid-1990s.
Released in 1996, the General Motors Co. EV1 lasted between 60 and 100 miles on a single charge.
Even the recently released Nissan Motor Co. Leaf has similar limitations, with an estimated battery range of just 100 miles.
Kurt Kelty, director of battery technology for Tesla Motors, said, “Our battery pack has 56 kilowatt-hours of energy. Other EVs on the market have about 20 or 24 kilowatt-hours.”
“The Roadster battery pack is over 120 watt-hours per kilogram,” he added. “That’s where our engineering strength comes in. We use a high energy density cell, and we pack it densely while also maintaining a high level of safety, reliability and long life.”
The emphasis at Tesla is to focus on what the company terms “energy density,” essentially a measure of the amount of energy stored per kilogram of battery mass. At its headquarters in Palo Alto, Tesla claims to maintain one of the most advanced battery development labs in the world.
Specifically, Tesla is developing technology that will allow consumers to easily replace used batteries with ones holding a full charge. The company plans to implement this innovation in the Model S sedan.
Despite the increased innovation in the field, driving down the cost of the batteries remains the greatest challenge.
Haresh Kamath, project manager in the energy utilization program area at the Palo Alto-based Electric Power Research Institute, said, “The main challenge with electric vehicle batteries today is their cost. It is a very large part of the difference in cost between an electric vehicle and a conventional internal-combustion vehicle.”
Tesla plans to release three different versions of the Model S sedan based mostly on battery life. The basic Model S with have a battery designed to run 160 miles on a single charge. It will cost $49,900 after a $7,500 federal tax credit.
The second battery option will have a 230-mile range, but will add about $10,000 to the price. The Model S with a 300-mile range should cost around $20,000 more than the basic version.
Ricketts, however, emphasized the importance of investment in battery technology. “Investing heavily in research and development, Tesla is proving that major breakthroughs are happening quickly,” she said.
Kamath said, “There are a number of manufacturers that are in the electric vehicle space, as well as in the electric vehicle battery space. While Chinese manufacturers are present, there are also Japanese, Korean, German and U.S. manufacturers that have competing battery technologies.”
“Lithium ion battery production is not very labor intensive,” Kamath added. “Competition is typically not driven by labor costs.”
Ricketts reports that new buyers are encouraged to charge their cars each evening using a standard power outlet in their garages. “Most of our Roadster owners find that they never even come close to depleting the battery. Charging is really just a matter of ‘topping up’ continuously,” she said.
Pohorsky said, “For the San Francisco Bay area, you can get from San Jose to San Francisco and back on one charge for a car that’s got a decent amount of battery in it. People need to sit down and really think about how much they normally drive in a single day, and that is surprisingly low.”
Concerns also persist over the impact that increased electric car usage will have on local energy grids. Kamath addressed this, saying, “While utilities do have to examine the effect of electric vehicle adoption on their distribution networks and may have to accelerate upgrades to their capacity in some places, at present, our analyses show that local power systems can accommodate the expansion of electric car adoption without much difficulty.”
He added, “The additional power drawn by electric vehicles is relatively small compared to the capacity of the grid, and a great deal of the charging is expected to occur at off-peak times, like the nighttime.”
A 2008 episode of the British television program "Top Gear" was particularly damaging to Tesla’s battery life reputation. In the episode, host Jeremy Clarkson is shown racing the Roadster against a similar gas-powered sports car when the battery is purported to have died, a claim that was eventually shown to be false.
At the time, officials at Tesla noted that the battery never dropped below 20 percent capacity while filming that particular sequence, despite what viewers were led to believe.
Clarkson, who initially praised the car, said in the episode, “If it does run out, it’s not a quick job to charge it up again. To fill the tank on a normal car, it takes a couple of minutes. To fully recharge the batteries on this from a normal 13-amp socket like this takes 16 hours. So to get from here to the top of Scotland would take more than three days.”
Ricketts noted that Tesla’s customers are often less concerned with the car’s battery life. She said, “With a range of 245 miles, the Roadster doesn’t worry many people. In fact, the range is often cited as a reason for buying the car.”
This has not stopped the company from employing some higher-profile strategies to emphasize that Tesla drivers have similar capabilities to drivers of gas powered vehicles. Ricketts said, “We have also made high-profile roadtrips in the Roadster — from California to Detroit for the International Auto Show, for example — to show that distance driving is possible in an EV.”
Tesla is hopeful that its technology will further the popularity of electric vehicles. “With longer ranges being achieved by EVs, and more successful distance tests being run, the public is starting to see how practical driving electric can be,” Ricketts said.
Centered on Palo Alto, the radii of the circles on the following maps show an approximate range for several different vehicles in the electric category. The Lotus Elise, a gas-powered sports car, is included for comparison.