Reserve Battery - Activation

Activation

Reserve batteries may be activated by addition of water, by adding electrolyte, by introducing a gas into the cell that is either the active cathode material or part of the electrolyte, or by heating a solid electrolyte to a temperature at which is becomes conductive. The missing element of the battery can be added before use in several ways. The battery can have water or electrolyte added manually, the battery can be activated when the system is dropped into the water (such as in a sonobuoy), or electrolyte can be stored in a capsule within the battery and released by mechanical means, an electrical trigger, or by spin or shock. A molten-electrolyte battery is activated by igniting a pyrotechnic heat source. The battery delivers current for a short time (seconds to a few minutes), but some thermal batteries can be stored 10 years or more without deterioration. Reserve batteries remain uncommon in civilian applications because of their higher cost and relatively short life after activation.

In missiles, reserve batteries typically use a small container of pressurized air to force the electrolyte from storage tank into the battery. For safe disposal, the air must be vented. This led to use of the term "venting" for preparing of any kind of battery for disposal, whether draining electrolyte from lead cells or full discharge of lithium batteries.

In ordnance, the batteries are activated by acceleration during gun firing, or by spinning the projectile in flight.