Aftermarket lithium-ion battery pack squeezes 150 MPG from a Toyota Prius

Posted by Humphrey Cheung

A new lithium-ion battery pack for the Toyota Prius may not lower gas prices, but it promises to make trips to the gas station less frequent – a lot less frequent.

Ontario (CA) – A new lithium-ion battery pack for the Toyota Prius may not lower gas prices, but it promises to make trips to the gas station less frequent – a lot less frequent.  Made by Hymotion and A123 Systems - the same folks that brought you the batteries in the Killacycle – this aftermarket kit converts the car into a plug-in hybrid and allows it to run on electric power for the first forty miles of a trip.  As you can expect, total gas mileage goes through the roof and company executives claim drivers can easily exceed 150 miles-per-gallon in the city and 100 MPG on the highways.

Pictures of the 150 MPG Prius ...

We inspected one of Hymotion’s specially outfitted cars at the Clean Vehicle Technology Expo in Ontario California.  The 175-pound battery pack installs in the spare tire well of the trunk and you still have the entire trunk space for cargo.  You can even lay the spare tire on top of the battery pack, but Nick Rothman, a kit installer for Green Gears, told us that some companies go without the spare and carry a can of “Fix a Flat” instead.

In your average Prius, the gasoline engine still does the majority of the work and the batteries merely take over at low speeds.  The Hymotion-equipped car, however, works much differently.  Owners charge up their vehicles with a regular 110 or 220 volt extension cord and afterwards the car will drive dozens of miles solely on electrical power.  From empty, the five kilovolt battery pack charges in about six hours with 110 volt and 3 hours with 220 volt electricity.

According to Rothman, the kit takes about four hours to install and a few more hours of testing and configuration.  Other than the extra batteries and an added charging outlet, the Prius remains stock and unchanged.

The Hymotion kits are currently being tested by several companies, but Ricardo Bazzarella, President of Hymotion, told us Prius owners won’t have to wait long to get their own kits and plans on having them available in the first quarter of 2008 for approximately $9500 dollars (installation included).