One problem related to propulsion system traction battery has been reported for the 2011 Toyota Prius. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2011 Toyota Prius based on all problems reported for the 2011 Prius.
Around 14 months ago (March 2024) I purcheded a replacment battery pack for our 2011 Toyota Prius form nexpower energy (also going by, project lithium, sodiumhybrid) based out of CA. The battery pack is a lithum pack that replaces the orginal nickel metal hydride pack. In the beginning of June 2025, the car through an battery error and went into limp mode wile my wife was driving, when I go home and plugged in my scanner to check the battery out I noticed that the cells were out of balance and some were becoming very over charged. My fear is that if the cells were continued to be overcharged an thermal runaway event might occure due to bms not being included with the overall pack.