http://www.edrivesystems.com/­faq.html

Some of the things that have changed, along with the decision to use different batteries than the ones in my EnergyCS prototype:

11. How is the EV range so much larger than a standard Prius with only 7 times as much battery? The standard Prius has a 1.3kWh NiMH battery but only uses about 25% of it (or 300Wh). The EDrive lithium battery is over 9kWh and up to 75% of it is used (or 6400Wh). Therefore the EDrive system actually has over 20x more energy (6400/300) at its disposal.

16. How safe are the advanced lithium-ion batteries? The advanced lithium-ion battery system developed by EDrive has been designed with safety as a primary goal. Multiple innovating technologies spanning electronics, software and cell packaging have been developed to assure maximum safety and longevity for the battery system. Safety and long life are primary concerns for vehicle applications.

17. How long will the lithium-ion battery last? Testing indicates that the batteries should last over 5 years in an EDrive equipped Prius, with 10 or more years being possible. Depending on how the 'end of life' is defined, the battery may last the life of the vehicle (ie if 30 miles of boost range is deemed sufficient from a system that initially provided over 50)

18. How much does the EDrive battery weigh? The EDrive battery pack weighs approximately 150lbs. The Toyota NiMH battery removed from the vehicle weighs over 70lbs. The net weight increase is thus approximately 80lbs.

21. How safe is the EDrive option? The EDrive system is designed with safety in mind. The advanced lithium-ion battery system provides exceptional safety and the rear battery pack is being designed so as to have minimal effect on the existing rear crumple zone in case of a collision.