Green Car Company Rides Wave of Plug-in Hybrids, Battery Technologies


A lot of people modify their cars, but the alterations to the hybrid Toyota Prius I was test-driving last week were more than just a fancy paint job or cool rims. In addition to the standard regenerative braking battery, I was packing an A123 Systems Hymotion L5 lithium ion battery that charged by plugging into a wall socket. The Prius had been modified and lent to me for a few days by Bellevue, WA-based Green Car Company.

The mechanics at Green Car Company had installed the Hymotion battery in the trunk of the car, right behind the socket where the power cord to charge the car plugs in. The Green Car Company rents and sells a variety of environmentally friendly cars and bikes, including biodiesel vehicles. It also performs maintenance and modification for those cars, such as the plug-in module for the Hymotion battery.

Hybrid cars are growing more popular all the time, and many companies are competing to develop the best possible battery—long-lasting, easily recharged, and cheap. The L5 battery has a longer life than the standard Prius battery, though it requires a power grid to charge. It also makes the gas engine of the car more efficient, improving the overall energy efficiency of the car compared to standard hybrids. A 2009 modified Prius at Green Car Company costs $41,999, while a standard Prius costs $22,516, according to Kelley Blue Book. Toyota is developing a plug-in version of the Prius, but according to Green Car Company, that version will actually cost more than modifying the current, standard Prius.

The main idea of installing the plug-in battery is that drivers will be able to travel 100 miles or more on every gallon of gasoline, with a range of 30 to 40 miles on just the battery itself. One of the nicer points for me was that even if the battery did deplete all the way, the car would then become a standard Prius hybrid and use its factory-installed battery.

The plug-in battery maker, A123 Systems, based in Watertown, MA, acquired Toronto-based Hymotion and Hymotion’s plug-in hybrid modules in May 2007. A123 developed the nanophosphate lithium ion battery, which has a longer life and charging ability than standard lithium batteries. Hymotion used these A123 batteries in its conversion kits even before being acquired. Last Wednesday, A123 announced it had received $249 million in grant money from the U.S. Department of Energy, part of the $2.4 billion in federal grants given out for companies working on technology for electric vehicles. A123 plans on using the money to expand and improve its lithium ion battery manufacturing capabilities in the U.S.

To give people an opportunity to test-drive a car installed with a Hymotion battery, Green Car Company is having an event on August 22, and will offer a raffle prize of an electric bike for those who average the highest miles-per-gallon on their test-drive. Of course, the main difference compared to a regular Prius is not so much in the driving as in the charging of the battery. Driving the modified car is not really different from driving a regular Prius, although the extra battery weighs about 200 pounds. Green Car Company can install improved suspension for the Prius when they put in the battery so that the weight doesn’t cause problems. It’s not difficult to plug it in, and there’s a helpful flash of the brake lights when the car is charging. Even better, the car cannot turn on while it is plugged in, eliminating the possibility of unfortunate mishaps like driving away while still plugged in.

The standard Prius battery is a nickel metal battery, which is capable of being recharged via braking. But this kind of battery can lose some of its ability to hold a charge from repeated charging and have a higher rate of self-discharge, further decreasing its shelf life. Lithium ion batteries don’t have that charging issue and tend to be lighter than nickel batteries. There are some regenerative lithium ion batteries, but they are prohibitively expensive for most cars, making the plug-in option a viable compromise between the two types of batteries by having the more efficient lithium battery without the higher cost of making it rechargeable from braking. It only costs 16 cents in electricity to charge the battery from empty to full, according to the Green Car Company employee who showed me how to drive and charge the car. From my own driving experience, even a whole day of driving did not deplete the battery entirely to empty.

The other main reason people buy hybrids is, of course, the lesser impact they are supposed to have on the environment. The Prius is already one of the cleanest vehicles sold in the U.S., according to the Environmental Protection Agency. Green Car Company says even if the electricity for the car comes ultimately from coal power plants, there is still a 50 percent reduction on carbon dioxide released into the atmosphere compared to a regular car.

There’s no denying the growing trend toward greener vehicles, but at the moment, with so many different types of alternative fuel vehicles, it’s uncertain which, if any, of the options will have the greatest success. At the moment, the plug-in modification seems like a good choice if you buy a hybrid car for the long haul and travel in a way that maximizes the efficiency of the battery. It may just be that the technology for hybrid and alternative-fuel cars in general needs advancement, something the industry is finally getting funding for. But plugging in a car may soon become just as common as plugging in any other appliance.

Eric Hal Schwartz was an intern in Xconomy's Seattle office. Follow @

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