At the tourist information centre in the Haus der Natur there is at least one socket available for charging the e-bike battery free of charge (mains adapter required).
Please note the opening hours at: Tourist Information Feldberg Haus der Natur (hochschwarzwald.de)
E Bike Ladestation
Dr.-Pilet-Spur 4
79868 Feldberg
Dr Pilet Spur 4