Milnes high tension battery, 1930-1935.
© Science Museum / Science & Society Picture Library
This high voltage (120V) lead-acid accumulator, made by Milnes Radio Co, Yorkshire, would have been used with domestic radio apparatus. Each glas jar contains two lead plates and the electrolyte-dilute sulphuric acid. Typically, consumers would have such batteries recharged at their local car garage, where a mechanic would connect the spent battery to an electricity supply to reverse the chemical reaction, before topping up with water to compensate for any evaporation. The battery is shown with the lid removed.