BATTERIES FOR AIRCRAFT AND SUBMARINES

BATTERIES FOR AIRCRAFT

The on-board power requirements in aircraft have undergone many changes during the last three or four decades. The jet engines of the aircraft which require starting currents of about 1000A impose a heavy burden on the batteries. However, these days this load is provided by small Turbo-generator sets and since batteries are needed only to start them, the power required is much less. These batteries possess good high-rate capabilities in order to supply emergency power for up to 1 h in the event of the generator failure. However, their main service is as a standby power for miscellaneous on-board equipment. Usually, batteries having 12 cells (of a nominal voltage of 24 V) with capacities of 18 and 34 Ah at the 10 h rate are used. In order to reduce weight, only light-weight high impact polystyrene containers and covers are used and the cells are fitted with non-spill vent-plugs to ensure complete un-spill-ability in any aircraft position during aerobatics. Similarly, special plastic manifolds are molded into the covers to provide outlet for gases evolved during cycling.

BATTERIES FOR SUBMARINES

These batteries are the largest units in the traction service. In older types of submarines, the lead storage battery was the sole means of propulsion when the submarine was fully submerged and, additionally supplied the ‘hotel load’ power for lights, instruments and other electric equipment. When the introduction of the snorkel breathing tube made it possible to use diesel engines for propulsion, battery was kept in reserve for emergency use only. Even modern nuclear-powered submarines use storage batteries for this purpose. These lead-acid batteries may be flat, pasted plate or tubular positive plate type with 5 h capacities ranging from 10,000 to 12,000 Ah. One critical requirement for this service is that the rate of evolution of hydrogen gas on open-circuit should not exceed the specified low limit. Double plate separation with the help of felted glass fiber mats and micro-scoporous separators is used in order to ensure durability, high performance and low standing losses.