EV Battery Swapping's First Real Test

Better Place has completed a trial for taxis in Tokyo

5 min read


23 March 2011—Smartphone owners know all about battery anxiety: Spend too long playing games and the battery icon flashes ”empty” the next time you need to make a call. For drivers of electric cars, the problem is more serious: They can’t just walk over with a 20-liter jug of electricity from the nearest charging station, and even if they do manage to glide into a station on their last electrons, it could take hours to top off a car battery.

Silicon Valley start-up Better Place claims it can change all that. Its recent trial in Tokyo allowed drivers to switch batteries at stations in minutes, letting them continue their journey and leaving the recharging to Better Place. The company might also help Japan find something to do with its declining number of gas stations, says Minoru Nakamura, head of the crude oil distribution unit of Japan’s ministry of economy, trade, and industry.

The Tokyo trial, which involved three taxis, was the first real-world test for battery swapping. Results from the first four months of the seven-month trial showed that the prototype batteries don’t require any special care—the computer-controlled battery-charging bank was able to keep the batteries in good condition by controlling temperatures and choosing when to charge and use each one. By the end of the trial, on 20 December 2010, Better Place claims the taxi drivers had grown more comfortable using more of the battery between visits to the battery-switching station.

For now, the batteries require recharging every 90 kilometers or so, with plans for a 160-km range on production models. Those distances are nothing special by electric vehicle standards, but Better Place hopes to show that swapping batteries can be just as easy as refilling a tank of gas.

”You’re essentially amortizing the initial investment of batteries over the difference between gasoline price and electricity,” explains Kiyotaka Fujii, president of Better Place Japan. ”The longer you drive, the better off you are, so we chose a segment that is closest to regular passenger vehicles: taxis.” Better Place also has plans to move into the consumer vehicle market in Israel and Denmark, where driving patterns more closely match the short-haul abilities of electric vehicles and the governments encourage the use of electric cars with tax breaks.

The Tokyo demonstration was underwritten by a grant from Japan’s Agency for Natural Resources and Energy, which will evaluate trial data and decide whether to support the next step, which might involve scaling up the demonstration. Nakamura says that so far it’s clear that ”systems of standalone type...are not feasible or economical, [so they] should be connected to each other as a network.” Fujii agrees: ”We think we need four or five stations [in order] to be profitable.” Each station could handle about 200 taxis.

Tokyo, with its 60 000 taxis and two extensive subway systems, should be fertile ground for anyone providing local transport, but Better Place won’t be able to make electric cars work by itself. ”We need competition,” Fujii says. ”It’s like mobile phones: No single company operates one single infrastructure.” Instead, companies agree to share access to their networks with users of other networks—something Better Place could do if other companies stepped in.

Nakamura, who says it’s still too early to judge the technical results of the trial, notes that ”this new method is very efficient, especially regarding public transportation.”

About the Author

Lucas Laursen is a freelance journalist based in Madrid. In the September 2010 issue ofIEEE Spectrum, he wrote about a computer system that warns egg farmers when hens are going to start murderous rampages.


Lucas Laursen: Tokyo may be famous for its tuna market but it’s also home to 60 000 taxis. That makes it a meat market for anyone who thinks they can build a better taxi, like the people at Better Place, a Silicon Valley start-up which is trying to electrify cars all over the world.

Kiyotaka Fujii: Tokyo is one of the largest taxi markets in the world. Tokyo actually has more taxis than London, Paris, New York combined.

Lucas Laursen: That’s Kiyotaka Fujii, president of Better Place, Asia Pacific. He was in charge of the first real-world trial of an electric battery-switching station here in Tokyo.

Kiyotaka Fujii: What we’re trying to do is, ultimately we’re trying to answer the question is—are taxis possible to be electrified.

Lucas Laursen: Because of their big batteries, electric vehicles are relatively expensive to buy up front. And they face another, bigger challenge: Drivers worry about how far they can drive on a charge and how long it will take to recharge their battery. There’s even a name for this problem: range anxiety.

Potential customers are like a worried suitor agonizing about the cost of an engagement ring or whether the marriage will last.

The people at Better Place think that they have a solution to both the high cost of batteries and range anxiety: It’s promiscuity. Instead of asking drivers to leave their cars charging a battery for hours, or performing high-speed charging, which can hurt battery life, the company has designed a robotic switching station that swaps out spent batteries and replaces them with full ones, so drivers can get back on the road in minutes.

Sure, it means the car no longer has a monogamous relationship with its battery, but if this trial in Tokyo is any indicator, it might just get more drivers to pop the question to their own electric car.

Better Place is still analyzing data from their eight-month trial on how the batteries handled the intense routine of a taxi fleet, but they already know that the battery-switching technology was a hit with the test drivers. Switching a battery feels more like going through a drive-through car wash than filling your tank at a gas station. It’s quick and easy.

Here’s how it works:

The driver pulls up to a gate and activates the battery switcher using a proximity card, sort of like a garage door opener.

Then he pulls forward in a track that keeps the car aligned with the battery-switching equipment.

The equipment is hidden underneath the track, below a white trap door that only opens when the car is in the right place.

Inside the station there’s a whole rack of spare batteries. The Better Place computers charge based on the price of electricity and the taxi fleet’s demands. It’s like an online dating service for electrons and cars.

When the car is in place, a system of sliding trays brings one of the fresh batteries below the car and another tray removes the used battery.

Then the spent battery goes back to the charging rack and the taxi heads out to the street. Don’t worry, they’ll dance together another day.

At first glance, all this custom equipment looks like it could only work if everything matches up. But Fujii says it should be flexible enough to accommodate new kinds of batteries.

Kiyotaka Fujii: The exchange mechanism is not necessarily heavily dependent on the batteries.

Lucas Laursen: In fact, that seems to be one of the main principles behind Better Place’s plan: The hardware isn’t the important part. The company’s leaders compare their business to a cellphone network: The cars are like cellphones: There can be many different kinds and they should be able to roam between different networks. But Better Place wants to sell you miles instead of minutes.

Kiyotaka Fujii: We look like, to the other stakeholders, somebody who can operate these stations, the infrastructure operator, that’s one basic thing but the other thing they are looking at us, is demand aggregator.

Lucas Laursen: For now, Better Place is only aggregating demand from the taxi industry, whose cars drive many miles within a compact area. But the company is also installing consumer charging stations in Israel and Denmark in the next year, and it has plans to build in Australia, Hawaii, and Silicon Valley. The technology and applications may vary from region to region, but for electric taxis in Tokyo, at least, the light is green.

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