Kiepe Electric to supply new battery packs for King County Metro’s trolley bus fleet

King County Metro is preparing its trackless trolleys for a power boost that will increase their ability to travel farther off wire and continue service to the region. This improvement is a part of the $26 million agreement that was finalized in September 2024 with Kiepe Electric to supply new, improved battery packs for the agency’s trolley fleet.  

King County Metro’s current fleet of 174 trolley buses went into service  2015 through 2017. The fleet had off wire capabilities that were modern for the time, allowing buses to detour around incidents and construction for short distances. 

The new battery packs will provide 72 kwh to each trolley – nearly triple the energy capacity of the current battery packs. This is expected to extend the range of operation off wire for when there are incidents blocking the trolley route, or nearby construction activity that requires deenergizing the overhead wires that power the system. These types of larger disruptions needed King County Metro to temporarily replace affected trolleys with diesel hybrid buses. However, the new extended range will allow the electric trolleys to continue to operate, helping the agency to reduce its emissions. 

The batteries are charged while traveling in-motion, so no other infrastructure upgrades are needed outside of the bus batteries and charging components. The new batteries were tested in four of the trolleys – two 40-foot trolleys and two 60-foot trolleys – for over 1,000 miles. The tests confirmed the new battery systems provide substantially more off wire range than the battery systems on the existing trolley fleet. 

These new batteries will ensure the trolleys will keep rolling into the next generation as King County Metro continues its transition to a zero-emission future.