Intelligent Power Unit (IPU)
WARNING: This page is about a different car, the 2011 Honda Insight and 2010 Honda Insight. However, it is still accessible from the selected car via links, so may be relevant.
The IPU consists of the power control unit (PCU), the battery module, and the junction board. The IPU is located under the cargo compartment to lower the center of gravity of the vehicle and to increase space in the vehicle interior.