Adelman is limited by some of the restrictions that Toyota built into the Prius, such as the 34 mph speed limit when running solely on battery power. Should Toyota come out with their own PHEV Prius (which, in current testing, goes 62 mph on batteries), Adelman said, they will give Plug-in Conversions an even more fun vehicle to work with.
The additional packs Adelman uses are Nilar nickel-metal hydride packs. NiMH batteries are the ignored child of the current battery boom - everyone is looking towards lithium technology - but Nilar's Kurt Jensen says their time is not over yet. Jensen was also at the booth and spoke with AutoblogGreen about the Nilar battery technology and some of the patent issues that automakers face when working with nickel-metal hydride batteries. He didn't get into great detail about the intellectual property issues that cover this technology, unfortunately. You can hear Adelman talk about the car here (8 min, 5 MB) and Jensen talk about the batteries here (10 min, 7 MB).