The Blocking Bad Batteries Act prohibits the Department of State from purchasing batteries made by seven major Chinese battery manufacturers, including CATL and BYD, starting October 1, 2027. The restriction applies to batteries produced or substantially manufactured by these companies or their successors. The bill gives the Secretary of State authority to issue waivers if purchasing from these manufacturers is deemed important to U.S. national interests, but any waiver must be reported to Congress with a detailed justification. This legislation effectively bars the State Department from relying on Chinese battery suppliers, aligning with broader efforts to reduce U.S. dependence on Chinese battery technology and strengthen domestic supply chains in this critical sector.