Tech Talk

It never rains but it pours, as they say. No sooner had our feature on the Sawyer family's plug-in Prius hit your screens (and mailboxes) than fast-breaking news overtook us: Hymotion announced a plug-in hybrid conversion kit for less than $10 000.

The company is now called A123 Hymotion, to reflect its purchase by battery maker A123 Systems. Their new L5 Plug-In Conversion Module supplements the Prius's stock 1.3-kWh nickel-metal-hydride battery pack with a 5-kWh pack based on A123's iron-nanophosphate lithium-ion cells.

Several features distinguish this kit from others now being offered, including the Sawyers' conversion, performed by Hybrids Plus of Boulder, Colorado. For one thing, it's been engineered and crash-tested to meet all applicable Federal new-car safety standards. For another, the converted car meets new-car emissions standards--which not every plug-in conversion does, including earlier versions of Hymotion's own kit.

And finally, it costs a lot less than the Sawyer family's conversion did: They paid Hybrids Plus $30,000 for a "PHEV-30," meaning their plug-in gets roughly 30 miles of pure electric range from its 4.5-kWh replacement pack plus another 4.5-kWh auxiliary pack. Those packs, by the way, also use A123's cells. Hymotion, on the other hand, quotes 30 to 40 miles of "electrically assisted" range for a third of that: $9,995.

Left unspecified, however, is the distance that the Hymotion kit will run in pure electric mode, without switching on the internal-combustion engine. The answer, as always, lies in the car's duty cycle: how heavily it's loaded, how agressively it's driven, the mix of speeds, and even such factors as how many hills it climbs.

We'll leave it to road testers to offer their real-world experience. And no doubt the highly active PHEV community will weigh in, from the always-energetic Felix Kramer at CalCars to the many members of the Electric Auto Association's very active PHEV mailing list.

After you read the feature on the Sawyers' car, by the way, check out both the audio slideshow on the conversion steps (my first audio slideshow) and the web-only summary of automakers' plans to introduce production versions of plug-in hybrids.