Toyota Prius adds a plug

Toyota has recently been rolling out models of its Prius PHV plug-in hybrid for evaluation in test markets.

About 150 vehicles are currently being placed in cities within California, New York, Colorado, Oregon, Pennsylvania and Washington, D.C., during the next year for evaluation and feedback. Another 450 vehicles are being placed in other evaluation sites around the world.

The new model replaces a nickel-metal hydride battery pack with a longer range lithium-ion battery pack that can be recharged directly from an electrical outlet. Compared to a standard Toyota Prius, which employs a gasoline engine to drive the wheels after accelerating to 25 mph, the PHV can drive at highway speeds in electric-only mode. It will only revert back to full hybrid mode when the battery pack has dropped below its minimum energy threshold.

The electric-only range of the Prius PHV is about eight to 13 miles before the gasoline engine takes over.

The Toyota Prius PHV allows the electric motor or the gasoline engine or both together to drive the wheels of the vehicle.

Even though the smaller lithium-ion battery pack is range-limited, the recharging time for the Prius PHV is just 1.5 hours from a 220 VAC outlet or three hours from a 110 VAC outlet. By comparison, the Chevy Volt and Nissan LEAF require at least eight hours to recharge their larger lithium-ion battery packs from a 220 VAC outlet.

The plug-in hybrid performs identically to a standard Prius hybrid in electric-only mode but should conserve more gasoline, depending on driving habits and road conditions. Road tests for gasoline consumption have averaged 58 mpg to 75 mpg.

On the PHV dashboard, there is an extra wide monochrome display that shows ongoing system information in addition to the color LCD touch screen display mounted on the center console. In the past, Prius drivers tapped the color console LCD touch screen display to toggle between different data presentations. This need to constantly switch between screen displays should be minimized with the new model Prius PHV.

The Toyota plug-in Prius PHV hybrid will not be available to the general public until 2012, but impatient Prius owners have the option of converting their cars to plug-ins.

Several small third party conversion companies have sprung up over the last several years to offer proprietary plug-in upgrades to existing Toyota Prius models. These upgrades are based on common open-source software and hardware standards defined by the California Cars Initiative, a group who promotes hybrid cars. Felix Kramer has led the CalCars effort to design a basic Toyota Prius upgrade template that can be expanded by individual commercial companies to provide even more range and features.

A lithium-ion battery pack, SAE J1772 receptacle and separate on-board charger, added to the trunk space of a model 2004 to 2009 Prius, can provide a 35-mile electric-only range to the vehicle, even at highway speeds. Interior display screens monitor the state of charge of the original nickel-metal hydride battery pack as well as the additional plug-in lithium-ion pack. These upgrades allow Prius owners to regularly exceed 100 miles per gallon after installation.

Prius owners considering a plug-in upgrade by a third-party company should check to see if this modification will void the original Toyota battery warranty. Some conversion companies have maintained good relations with their local Toyota dealerships and established a proven track record of successful installations, so that Toyota owners are able to keep their original NiMH battery pack warranty after the plug-in upgrade has been performed.

For more information about the CalCars and third party Toyota Prius upgrades, visit For more information on the Prius PHV demo program, visit the Toyota website at

Stan Hanel has worked in the electronics industry for more than 30 years and is a long-time member of the Electric Auto Association and the Las Vegas Electric Vehicle Association. Hanel writes and edits for EAA's "Current Events" and LVEVA's "Watts Happening" newsletters. Contact him at