The cells and batteries covered by this specification are intended for use in supplying electrical power to equipment on board aircraft. Primary consideration must be given to the safe use of a non-lithium cell or battery; however, if the application requires the use of a lithium cell or battery, the following guidance will be considered.

Type I lithium cells or batteries are preferred for all locations within the aircraft. The frequency of occurrence of violent venting or explosion of Type I lithium cells or batteries is improbable during normal operation. If venting does occur, the vent products are non-toxic and non-corrosive; they would not immediately endanger personnel nor cause severe equipment damage.

Type II lithium cells or batteries are not recommended for use in cockpit or crew compartment areas unless appropriate eye and respiratory protection are provided. Type II lithium cells or batteries can be used in other areas of an aircraft only if vent products will not contaminate the cockpit or crew compartment areas or high priority equipment or systems. The frequency of occurrence for violent venting or explosion of type II lithium cells or batteries is remote during normal operation. If venting does occur, the toxic and corrosive vent products are likely to endanger personnel and cause severe equipment damage.

Type III lithium cells or batteries are expected to be used in such applications as aircraft computer memory backup.

The smallest possible cells or batteries must be selected for the mission power requirement.

In development programs, assembly of batteries by user personnel must be avoided.

A special compartment must be designed for the cell or battery for isolation from the electronics of the end item equipment or weapon system. The compartment must have no interior projections or sharp edges that could damage the electrical insulation around the cell or battery. The cell or battery must be secured within the compartment to reduce shock and vibration to the levels required for end item use. The compartment must be designed either to provide vent paths or else contain gases emitted by a venting battery. If vent paths are to be used, they must be identified on the compartment drawings. If the compartment is designed to contain the vented gas, the drawings must identify the pressure-containing capabilities of the compartment (including pressure level) and the containment designs or methods.

Battery or cell switches in the end item equipment or weapon system must be carefully selected to prevent accidental cell or battery turn-on. No switching may occur in the ground leg(s).

Cells or batteries with different physical characteristics, chemistries, or electrical parameters must not be used concurrently in the same electrical circuit.