The Draw Of Plug-In Vehicles

Of the 58 new vehicle introductions anticipated at the 2009 North American International Auto Show, few will generate more interest than the redesigned Toyota Prius. One group of enthusiasts who are particularly anxious to see that vehicle are those who convert Priuses from hybrids to plug-in electrics.

The fact that Toyota plans to release a factory-built PHEV sometime in late 2009 or early 2010 hasn't stopped these die-hards from converting their cars. Nor has the $7,000+ price tag for the work. Kits that run on Li-Ion batteries can cost twice as much, but even that's not much of a deterrent.

The primary motivation right now for converting a Prius to PHEV status clearly isn't cost-saving. Drivers who are particularly concerned about their impacts on the environment are most likely to seek out the conversion. Likewise are the hobbyists who are simply interested in mechanics of conversion.

Among hybrid vehicles, the design of the Prius lends itself nicely to PHEV conversion, and it is this aspect that the converters are most interested in. On the outside, the 2009 Prius doesn't look radically different than the current model, but the hobbyists are acutely aware of the fact that the 2004 redesign of the original Prius is what opened the door to relatively easy PHEV conversions in the first place.

Conversion kits also exist for the Ford Escape/Mercury Mariner, but fewer of these cars have been converted. Hybrid designs from other makers don't really lend themselves to conversion and would require a major overhaul, largely because of the way the electric motor and the vehicle's gasoline engine interact.

Conversion is a specialty niche, and for those interested in pursuing it, it is possible to find shops that will convert your vehicle to PHEVdom. The cost of the batteries is the biggest determinant in the overall bottom line. Lead-acid conversions are the least expensive. Nickel-metal-hydride conversions are mid-range in cost, and conversions that use lithium-ion formulations in the battery packs are most expensive.

Lithium-ion batteries are superior from an energy density perspective, but their cost is significantly higher and the availability is lower. Added to that are remaining questions about their safety. A converted Prius PHEV that used a lithium-ion power pack caught fire and melted down over the summer, and although the fire's cause is still under investigation, the most likely explanation for the mini-disaster centers on a defective lithium cell.

The conversion kits for sale today enable a converted vehicle to plug into a standard 110-v household outlet for recharging, and will provide more than 100 miles of all-electric drive between recharges. For many people this range exceeds their normal commute.

In the long run, questions still remain about the viability of PHEVs. Municipalities are primarily interested in the recharging infrastructure that may be needed to support a large number of plug-in vehicles. Although munis could charge users for access to outlets, the outlet infrastructure and the chargeback mechanisms are a tough sell in areas that are particularly hard-hit by the current recession. Cost-conscious consumers are also concerned about their ability to recover their investment in conversion, and the impact of conversion on the manufacturer's warranty. Utilities are also concerned about the impact of a large number of plug-in vehicles on the grid at certain times of the day, and with the growing need for added production capacity.

Toyota isn't particularly concerned about the impact of PHEV conversions on its plug-in sales. After all, a factory-produced, fully warranted, dealer-serviceable PHEV, even at a higher cost is likely to be attractive to a larger consumer segment, and the PHEV conversions are only heightening interest in plug-in vehicles. Reportedly, the Toyota-made Prius PHEV has an all-electric range of only about ten miles but this will likely be extended with technology improvements.

For more information about converting a hybrid vehicle to a PHEV, visit CalCars.org.

Photo Credit: Sanja Gjenero