When PHEV battery is depleted, vehicle resumes normal operation using factory battery. And even when using PHEV, stock battery's power level are showed…The five kilovolt battery pack will charge up from completely empty in about six hours with 110 volt and 3 hours with 220 volt electricity. Installation of the kit takes about four hours and a few more hours of testing and configuration. Other than the extra batteries and an added charging outlet, the Prius remains unchanged. Kit integrates with vehicle without removing factory battery, and installation also includes reinforced impact resistant construction. 

The Hymotion kits are currently being tested, but will be available to Prius owners by the end of first quarter of 2008. Price is not yet set, but will be approximately $9.500 dollars (including the installation) ~6.000€. This kit is a great addition to all wishing to have an electric car, that behaves like one as well. Green, economic, and quiet! All in all, we liked the quality, construction and integration/installation of Hymotion's Prius PHEV kit! With specified operating temperature range from -20C to 45C, and proper charging temperature range from -10C to 35C this will be a great buy for many owners! If it only proves to be imune to problems (like great impact on range when temperature is below zero).