The Féry battery was developed during the 1st World War by the physicist Charles Féry upon request of the general and engineer Gustave Ferrié in order to supply the military telegraphy equipment.
Most of the batteries of this era were of Leclanché type and required manganese dioxide which is found in a rare mineral in France and which had to be imported from Germany. Faced with a clear problem of supplying this metal, Charles Féry is looking for a way to replace manganese dioxide with oxygen in abundance in the air. He is thus developing a brand new type of battery, air depolarization cells.
The Fery pile consists of a vase with a cathode made of porous carbon tube protruding from the vase and zinc at the bottom. The hydrogen generated in the lower part of the coal is recombined into water near the surface where oxygen is more abundant.
These cells have the advantage of being easy to maintain, to have a satisfactory production cost and a large mass capacity. They could supply a minimum capacity of 90 amp hours with 100 grams of ammonia salt for a total weight of 2 kilograms.
The use of these batteries was widespread in the 1920s, the Gaiffe-Gallot company will sell more than 1,500,000 of them to the French administration.
