The voltage was 1.5V. http://www.radiomuseum.org/r/strache_trocken_element.html DataInventory Number: Ele90Date: c.1930Maker: Strache & Co Fabrik, LeipzigInstrument Categories: ElectricityInstrument Type: Electric battery PlacesLocation: 26ο Γενικό Λύκειο Αθηνών - 26th High School of Athens Origin: 2ο Γυμνάσιο Θηλέων Αθηνών - Second Gymnasium for girls, Athens