Some batteries are produced with "dry
charge" processes to allow longer shelf life or to ease installation. Either
plates or elements can be "dry charged." Dry charge of plates can be done with
vacuum, with steam, or with other inert atmospheres. In particular, negative
plates must be precluded from exposure to oxygen until they are thoroughly
dried. Before dry charge, plates are "tank formed" in open containers. Formed
plates or groups are washed thoroughly before drying.
Some manufacturers also have produced
"damp-dry-charged" batteries. These units may contain a small amount of
residual electrolyte and additives to preclude damage to grids, active
material, and separators during storage.
In some cases, formed negative plates
are allowed to oxidize in air before assembly. These cells must be given an
activation charge before being used in their application.
Dry charge oven settings
Oxygen content of inert gas, where
Tank formation control (current,
pH of rinse water.
Completeness of formation
Completeness of dry charge (charge
Electrolyte impurities (organic,