I was reading this old thread. Prius Battery Information | PriusChat if it’s true, I wonder what ever became of the idea. “have you seen the replacement bats from china ? - instead of 28 packs, you have only 14, they take nimh D cells? to make a block of 12 of them to give the same voltage and amps of the parametric grid oem's -- so instead of 28 slises u have 14 to simplify things and much better looking connectors”
Prius started with a D-Cell pack. In fact, that battery difference is how Gen-0 was defined (the Japan-only model). When rollout happened in the United States, we got the upgrade to prismatic packaging... hence Gen-1.