Article 43 Accumulator (storage) batteries and associated charging equipment

In every vessel of 12 metres in length and over to which these Rules apply where accumulator batteries provide the auxiliary electric power such batteries shall, together with dynamos or alternating current generators, be of sufficient capacity to provide an adequate reserve of electric power under all foreseeable service conditions. The batteries, their means of charging, charging voltage and current protection arrangements shall be effective and fit for their intended service.

In every such vessel not less than two dynamos or two alternating current generators each being capable of supplying sufficient auxiliary power for the safety of the vessel and maintaining the charge rate for the vessel's batteries shall be provided as a means of charging those batteries. Dynamos or alternating current generators may be driven by the main engine, subject to compliance with the provisions of paragraph (6) below.

In every such vessel the output of any dynamo or alternating current generator driven by a variable speed engine shall be based on the lowest operational speed of the engine. Throughout the entire operating engine speed range the dynamo or alternating current generator shall operate within its safe speed range.

In every such vessel accumulator (storage) batteries shall be housed in boxes, trays or compartments which are constructed to provide protection of the batteries from damage and ventilated to reduce the accumulation of explosive gas to a minimum. Where fans are fitted in exhaust ducts from compartments assigned principally to the storage of batteries they shall be of a flameproof type. Electrical arrangements liable to are shall not be installed in any compartment used principally for the storage of accumulator batteries. Lead acid and nickel alkaline batteries shall not be housed in the same space.

In every such vessel where accumulator batteries are used for starting the main engine not less than two batteries shall be available and each battery shall be capable of supplying adequate starting power and shall be of sufficient capacity to start the main engine or engines not less than twelve times successively if the engine is reversible or not less than six times successively if the engine is non-reversible, unless alternative means of starting are provided.

In every vessel of 19 metres in length and over but less than 24.4 metres in length to which these Rules apply one battery charging dynamo or alternating current generator shall be driven by an independent prime mover.