The main electrical systems supplied by the emergency power supply include navigation and communication equipment, emergency lighting, the fire and sprinkler pumps, the water tight doors and lifts, the steer gear and bilge pump. The system is automatically connected to the emergency switchboard and is automatically started if the main power source goes off.
The system is always located higher up and outside the engine room spaces. This insulates them from any damage and / or fire to the engine room.
Batteries in ships are backup source of power as an emergency system or form part of the standby power system installed to protect property and life from the various consequences of loss of primary power supply. They are an excellent source and store for electrical power since they are used as instant supply source of available energy. They are also used to provide low voltage direct current supply on regular basis to various machines on the deck and engine. Generally, there are two types of batteries used onboard a ship. the lead acid batteries and the alkaline batteries.
The Lead – Acid batteries also known accumulators consist of six separate cells in a series and each cell contains a lead peroxide plate as the positive terminal and a lead plate as the negative terminal which are both immersed in dilute sulphuric acid, the two plates are known as electrodes and the sulphuric acid is known as the electrolyte. This whole arrangement is kept in a leak proof casing. The two plates are joined by a wire and this develops a potential across this wire which eventually ensures current starts flowing through it. These batteries develop a total output of 12 volts since each cell in the series has a potential of producing 2 volts. The Lead Acid accumulators used currently has many plates which are interleaved in one cell.