The Prius batteries are NiMH and optimised for very high peak charge/discharge current (around 30C) and very long life (many tens of thousands of cycles/in excess of 8 years). To get this they sacrifice deep cycle ability; hybrids don't charge their batteries fully and never discharge them below about 30%.
This is not ideal for an electric vehicle, which normally needs a deep cycle capability in order to get maximum range from a given weight/size of battery.
It's possible to get hold of Prius battery packs from wrecked cars easily enough and often some of the cells will be salvageable (the pack is rated at 270 odd volts). They are only 6.5Ah though and pretty big and heavy for the capacity. One or two people have experimented with using Prius cells on the ES forum, without much success.
Jeremy
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