Electric mobility has been extremely fashionable for some time. Here, the by no means outdated German Federal Railroad had developed as early as the Fifties an ingenious concept for running trains electrically on non-electrified routes. Starting in 1954, the DB purchased 242 rechargeable battery powered rail cars as the class ETA 150, which were underway ecologically for decades in the north, south, east, and west. The units called "Rechargeable Lightning Bolts" or "Whistle Buoys" ran mostly in conjunction with the control cars (class ESA 150) made to go with them. Their very powerful Siemens traction motors even allowed the units to pull through cars, mail cars, or freight cars. Charging stations were set up in the respective areas of use for these units affectionately nicknamed "Rechargeable Lightning Bolts" or "Whistle Buoys". The range, depending on the type of battery, was an astonishing 250 – 500 kilometers / 156 – 312 miles. Numerous "Whistle Buoys" underwent the paint scheme change introduced in 1975 of ocean blue / ivory. Yet, the star for these progressive units began to sink. In 1995, the last set, designated since 1968 as 515/815 was retired. Two units remain preserved in Bochum-Dahlhausen and Nördlingen.
