Replaceable batteries in electric cars

By: Tom Ripley

Date: Monday, 14. December 2009

When your flashlight batteries give out, you replace them with new batteries and move on. So why shouldn't it be that simple with an electric car? Since the distance you can travel on a battery charge is the key limiting factor in an electric, many efforts up to now have revolved around inventing more efficient batteries that will increase vehicle range. But why not just make it easy to pull out the spent battery pack and replace it with another, just the way you might with a digital camera? The folks at Nissan and Renault agree, and they recently unveiled several electric cars with that feature at the Frankfurt motor show.

The Renault-Nissan alliance has been working for two years in close collaboration with a company called Better Place to develop rapid battery exchange stations. The fruit of that labor is QUICKDROP, an automatic battery exchange process that takes approximately three minutes. That's about the same amount of time -- or less -- typically needed to fill the tank at a gas station. But since you're not actually pumping gas, it's cleaner and more convenient for drivers. The good news, especially on rainy or snowy days, is that drivers do not even need to leave their vehicles.

The QUICKDROP system will first be deployed in Israel and Denmark, reasonably small countries with high population density and just the kind of places that promise to make the best use of the QUICKDROP's strength and minimize its weaknesses. In Frankfurt, Better Place announced a newly expanded agreement with Renault, committing both companies to a volume of at least 100,000 electric cars in both countries by 2016.

While changing out a spent battery quickly sounds appealing, it isn't always feasible or even desirable -- much like other things better left undescribed right now. Because of that, the Nissan-Renault brain trust has devised a couple of other ways for consumers to recharge their vehicles. One of them is pretty familiar. Much like the circuits Americans use for heavy appliances like clothes dryers, the 'standard charge' uses a domestic 220-volt 10-amp or 16-amp socket. Charging the vehicle's batteries this way requires between six and eight hours, so it is best-suited to a car parked overnight in a private parking area or during the workday in a shared parking lot equipped with the requisite charging apparatus. A secure automatic-key system discourages vandals from disconnecting the cable during charging, and the plug socket can be easily adapted to the current grid by an electrician.

Another charging method is the 'quick charge,' which employs a 400-volt socket using infrastructure that is still under development. This system will charge a 20-kilowatt battery in just 20 to 30 minutes, depending on the available current. Charging points using this technology are expected to be installed in residential areas near offices and shops.

To help make the project seem all the more real, Renault-Nissan displayed on its stand at the Frankfurt show four separate vehicles that use the technology. Certainly the most photogenic is the Twizy Z.E. Concept, an all-electric vehicle targeted primarily at 'busy city dwellers who need to pick their way through the urban jungle.' The two-seater is ultra-compact with a 10-foot turning circle and an overall footprint not much larger than a scooter, though it rolls on four largely shrouded wheels, giving the impression that it glides along.

A more conventional vehicle is the Zoe Z.E. Concept, which Renault suggests is proof that a zero-emission vehicle can also possess a dynamic, edgy, attractive design. The overriding concerns were the seemingly conflicting goals of elegance and efficiency, but the designers largely pulled it off. The Zoe Z.E. features 21-inch wheels, not something you'd expect on an electric vehicle (EV).

The Fluence Z.E. Concept is an EV for the family that envelops its four occupants in leather and gel, a la Dr. Scholl's. Passengers' feet rest on a light-blue translucent gel mat. For a greater sense of comfort, gel covers the brake and accelerator pedals too. Good range with significant carrying capacity were the over-arching design parameters.

The Kangoo Z.E. Concept provides a foretaste of the future for urban-based transporter and delivery companies. When it comes to comfort, space and safety performance, it draws on the strengths of the Kangoo, a popular European delivery vehicle. To facilitate loading, the hatch-type rear door and wide folding sill ensures that parcels and other items are easy to slide into the rear cargo area.

---France-based Tom Ripley writes frequently about autos and the human condition.

Related Links:

• Drivers.com article: Plug in car
• Drivers.com article: Another billion cars and Obama's green initiatives

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