Aug 13
A CNet story discusses converting the Prius to be a true plug-in Electric Vehicle (Es) that runs exclusively from battery power:
The Petaluma, Calif., company is selling $5,000 conversions that enable a Prius to drive a maximum 20 miles on full, lead-acid batteries, or $11,000 with lithium-iron phosphate batteries. Professional installation takes a day or two and costs about another $1,000.