Battery maintenance onboard ship

• Battery top side should be maintained clean and dry.
• Keep the vents clear and free of deposits.
• Check electrolyte levels and top up with distilled water till the plates are covered.
• Keep terminals connections tight free of corrosion and coated with petroleum jelly to prevent corrosion.
• Measure the relative density of the electrolyte as this indicates the state of charge of the cell.
  
• The relative density varies from 1.275 to 1.285 for a fully charged lead acide battery and falls to 1.1 when discharged fully.
• Maintain fully charged lead acid battery on trickle charge as they suffer internal discharge.
• An automatic battery charger will detect the battery condition and automatically change over to trickle charge and complete charging.
• Check the state of charge of the batteries by measuring the terminal voltage while supplying load current.
• The terminal voltage of a fully charged lead acid battery is 2.2 volts.
• The voltage falls to 1.75 volts after discharge.