Plug-In Tax Credit Passes House - Plug-in Prius may get $3,000

The patent does impose some restrictions, but should not be too big a deal in this case. As I understand one of the major changes in the '04+ Prius was the introduction of a dc:dc converter between the battery and the motor. The battery voltage was decreased to 201V from 288V, but through the dc:dc converter can be boosted to as much as 500V when needed to overcome back EMF at high rpms. In a similar fashion, the pack voltage could be increased and throttled back if needed in the dc:dc converter. Off hand I would think two strings of 321 cells or 54 existing modules (7.2V or 6 cells per module) would be a reasonable compromise between managing voltage and managing multiple strings. That would give you two 388.8V strings at 6.5Ah each, or 5054.4Wh. Pack cost should certainly be no more than 4X the current Prius, which I believe is ~$1600x4 = $6400 retail. Toyota's production cost should easily be half that, which puts it right in that $3k range of the tax credit.

Rob