T.S. Patriot State Engineering Manual

Patriot State was the training ship of the Massachusetts Maritime Academy from 1986 to 1998.

Emergency Battery System

The Patriot State is fitted with an emergency battery system. The purpose of the emergency batteries is to supply power to predetermined vital loads (e.g., navigation lighting, alarms) via the 120 V.D.C. panel. If the main switchboard should go into a low voltage situation, there is a 17 second delay before the emergency diesel generator accepts load. Therefore, the emergency batteries will supply these vital loads with power during the short time that is required for the emergency diesel generator to come up to speed. When the emergency diesel generator is up to or above 450 volts, it will take over the load and the batteries will go back to being charged by the battery charger. During this switching of load suppliers, there is only a momentary blink.

Under normal power, the batteries are charged by a battery charger supplied from the 450V emergency bus. When using shore power, the emergency battery loads are supplied by a 120 volt rectifier.

The emergency batteries are of the lead calcium type, similar to a maintenance free automobile battery. Each of the battery cells contains three components, the positive plate, the negative plate and the alkaline electrolyte.

The positive and negative plates are surrounded by the electrolyte, with a contact for each plate protruding through the casing. If a load is placed between the two contacts, the circuit is completed and electricity will flow. These batteries produce an average voltage of 2.0 volts per cell. Therefore, 60 cells are connected in series to give the required 120 d.c. to the battery bus.

The lead calcium battery was chosen because it has many good characteristics for emergency shipboard and marine use. Characteristics include low maintenance, reliability under poor operating conditions and very long life.

Direct comments to William Haynes whaynes@maritime.edu
Mon, Jul 1, 1996
TSPS Engineering Manual ©1995 Massachusetts Maritime Academy