Plug-In Hybrid Conversion Drives 70 Miles per Hour on Batteries

Making Toyota’s Prius into even more of an environmental super-achiever is certainly no easy thing. Yet, it’s been done in a variety of ways since this hybrid’s introduction by companies large and small, a trend that will no doubt continue in the years ahead. For example, we’ve seen the Prius and other hybrids modified to run on such fuels as propane, natural gas, E85 ethanol, and even hydrogen.

The latest trend focuses on vastly increased efficiencies through conversion to plug-in capability. This enables a hybrid with a bigger battery pack to charge up with energy from the electrical grid and run on battery power for extended periods, with the hybrid’s gasoline engine providing propulsion power after the juice is gone. This is being explored by automakers and independent companies with plug-in hybrids ranging from the venerable Toyota Prius to SUVs like the Escape Hybrid and Saturn VUE.

The 2004-2009 Prius is a popular car for conversion because it offers a lot of functionality and, of course, a style that’s appreciated by a great many people. Among the most formidable challenges in such conversions is often the resident Toyota software that tells the car how to operate, and its complex code has been a stumbling block for many over the years. One example that comes to mind is Energy Conversion Devices’ H2 Hybrid Prius that the company was championing as a testbed for its solid hydrogen storage several years back. Their elegant hydrogen conversion was straightforward enough … but the Prius’ code was said to be quite the challenge.

That software challenge has now been conquered, says a Southern California company called Plug In Conversions Corporation (PICC). The company reports it has completed a breakthrough software upgrade that allows its Prius plug-in conversion kit to allow driving up to 70 miles per hour on battery power alone. In the past, PICC says that Toyota programming has limited plug-in conversions to an electric top speed of 34 mph unless the electric motor was forced to run above its recommended speed range, so this is quite the accomplishment. The software upgrade is based on technology developed by Ewert Energy Systems, which has granted PICC exclusive rights for its use in Prius plug-in conversions.

PICC claims that its third-generation plug-in upgrade, with the aforementioned software and nickel-metal-hydride battery conversion kit, can allow Prius drivers to achieve up to 170 mpg fuel economy. That ethereal level of efficiency is said to be achievable by driving a PICC converted Prius on electric power until the battery is depleted, then on gasoline when the efficient internal combustion engine takes over. The company points out that this kind of fuel efficiency was recently confirmed by testing at the Department of Energy’s Argonne National Laboratory. That said, it’s important to point out that 170 mpg is not likely to be achieved by all drivers, all the time, since driving habits and circumstances greatly influence final mpg numbers in all vehicles including plug-in hybrids. In real-world use, PICC says its conversion will allow about 25 miles of all-electric driving at highway speeds. Argonne lab testing also confirmed SULEV (Super Ultra Low Emission Vehicle) emissions levels for the plug-in conversion.

The conversion adds about 220 pounds to a Prius, mostly due to the larger 6.1 kWh Gold Peak Industries nickel-metal-hydride battery pack that replaces the stock 1.3 kWh Toyota pack. Upgraded rear springs are added to compensate for this extra weight and retain the vehicle’s stock rear ride height.

And the cost? The software upgrade alone is available to new and existing customers for $2,000 to $2,500, while the PICC conversion kit goes for $12,500. Conversion is said to take about one day. The kit offers a three year warranty and batteries are expected to last about 10 years. While plug-in kits like these are still not cheap, their features appear to be improving and there will surely be takers as the automotive field continues its march toward higher efficiency and lower environmental impact.