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Tesla swaps Model S battery faster than a gas fill-up

Consumer Reports News

Tesla has long been coy in responding to rumors that the company's Model S will support battery swapping. No more. Last night at a California event, the company demonstrated the ability to hot-swap batteries in a Model S in about 90 seconds—twice as fast as a comparable gasoline fill-up.

To prove their point, the split-screen view of the official video (below) shows a Tesla employee racing to refill the gas tank of an Audi A8 at a local gas station. Of course, the winner of the race is a foregone conclusion. (Read our complete Tesla Model S road test.)

It takes as long to fill the Audi's gas tank with 23 gallons of gas, costing just under $100, as it does to swap new, fully charged batteries into two Model S cars, one after the other, using an automated machine. The ability to swap batteries counters a notable objection to electric cars—limited range. In daily driving, the Model S has exceptional range, well over 200 miles in our experience. However, it cannot go on a multi-state road trip without some planning and delays for recharging. Battery swapping could provide quick turnarounds for replenishing energy, granting the car long-distance capability—although planning would still be necessary. Plus, it is conceivable that it could be used to provide a larger battery pack as needed for an individual car that may have been sold without one, say to be used for a vacation week. (Check out: "The Tesla Model S is our top-scoring car.")

To learn more about electric cars and hybrids, visit our alternative-fuel car guide.

The Model S battery resides in a large flat pack that sits under the whole floor and forms a structural component of the chassis. In the demonstration, the cars drive over a pit in the floor, similar to an instant-oil-change bay. A robotic tray under the floor unbolts 1,000-pound battery pack, lifts it out of the way, and bolts a new one in, torquing it to factory specifications. It repeats the feat with a second car before the Tesla employee finishes filling up the Audi.

When Tesla began designing the Model S, the company formed a partnership with a company called Project Better Place, which developed such automated battery swapping machines, ran pilot programs in Israel and Denmark, and even got Renault to build an electric car designed to use the hot swapping machines. Later, the companies parted ways when Tesla wouldn't sign onto the universal battery format that Project Better Place wanted. Ever since, speculation has been rampant whether Tesla maintained the ability to hot-swap the batteries as the Model S reached production.

When Tesla visited our test track, we asked company representatives this question, and were told that it could, but that it wasn't a quick process and was designed more for maintenance and repair than for quick swaps. Shortly thereafter, Tesla announced extended warranty programs for batteries that would allow owners to get a new battery after 80,000 miles.

Now Better Place has folded, and Tesla founder and CEO Elon Musk announced that the company will begin rolling out such battery hot-swap stations in conjunction with its Supercharger stations in coming years. (He hinted that the stations may be renamed "Tesla Stations.") Supercharger stations can recharge the Model S batteries to half-full in 30 minutes or less, and Tesla provides the electricity for free. Musk implied getting a new battery at one of the hot-swapping stations would cost $100, the same as it cost to fill the Audi's gas tank. For that, you'd get a full battery, not one half full, and get it in significantly less time. (In fairness, the Tesla drivers in the company's demo didn't have to spend any time initiating or paying for the swap as the Audi driver did for the gas.)

Before hot-swapping Tesla batteries becomes a reality, questions remain about who will own the batteries, and how differences in the quality or capability of different batteries would be handled. Earlier this month, Musk announced that the company will double the number of Supercharger stations by the end of the year, and that by next year they will roll across the country so you can drive a Tesla from New York to Los Angeles. It's not yet clear how many of those "Tesla stations" might have hot-swap battery bays as well.

—Eric Evarts

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