Tesla developing battery swapping for five-minute recharging

After a string of high-profile announcements over the past few months, Tesla Motors has one more trick to reveal Thursday — a way to recharge its electric cars in a handful of minutes by swapping the depleted batteries for new ones.

Tesla Motors co-founder Elon Musk had hinted in the past that the company was working on a way to cut the recharging time of the Tesla Model S sedan to less time than it takes to refill a gas tank. Using the company's high-power home charger, the Model S needs about seven hours for a full refill, and while Tesla's own public Superchargers can cut that down to an hour, a Model S would need a couple of days to recharge from an everyday 110-volt plug.

Last night, Musk revealed on Twitter that the company would demonstrate a "live pack swap" on Thursday, and that "seeing is believing." Pack swapping isn't a new idea — electric taxicab companies at the turn of the 20th century swapped batteries for quick repowering, and an Israeli startup company called Better Place had been pushing the idea as a way to make electric cars mainstream for the past several years, envisioning a system where owners bought the car but rented fresh battery packs that could be changed frequently.

But Better Place filed for bankruptcy last month, after five years and $1 billion burned with few results. Unlike the batteries in toy cars, there's no uniform standards for electric car batteries. Most EVs use a battery pack designed specifically for that car; there's no commonality between the power supply of a Nissan Leaf and a Ford Focus EV. Trying to build a network of EV battery swap stations would be like enlarging the jumbled drugstore rack of hearing-aid batteries — and there simply aren't enough cars on the road for such a plan to make sense.

Tesla has already committed to building a nationwide network of free, public Superchargers for its Model S and future cars, and given Musk's other interests in building rockets and solar panels, its easy to imagine Tesla exploring a way to build its own battery swapping stations. But it's not a simple task; the battery pack in an 80-kWh Model S weighs about 1,200 lbs. And given Tesla's start-up resources, making battery swapping a part of everyday life would seem to call for a high level of automation rather than creating the 21st-century equivalent of the gas station attendant. We'll be at Tesla's announcement Thursday to see what's next.