If the batteries were rechargeable at all (some radio 'A' batteries [0] were), they could have been recharged by a small wind turbine [1]. [0] - https://en.wik

If the batteries were rechargeable at all (some radio 'A' batteries [0] were), they could have been recharged by a small wind turbine [1]. [0] - https://en.wikipedia.org/wiki/Vacuum_tube_battery https://en.wikipedia.org/wiki/Vacuum_tube_battery [1] - https://www.wincharger.com/ https://www.wincharger.com/