Like automobiles, aircraft mount batteries that are used in the ignition sequence for the engines and auxiliary power unit (APU). Unlike car batteries however, aircraft batteries are responsible for much more. If there is an electrical generation failure during a flight, the batteries will be required to provide power until the aircraft can land, and can also be used to restart the engines if a flame-out occurs.
Batteries also serve as a buffer regulating the DC network voltage to ensure acceptable power quality for the equipment connected to the network. Given these crucial functions, batteries are absolutely critical components on an aircraft that need to be treated carefully and maintained diligently.
Batteries come in two general types in aviation: nickel cadmium (Ni-Cd) and lead-acid. Lead-acid batteries are either vented or valve regulated, and are frequently used in light or general aviation aircraft. Vented Ni-Cd batteries are primarily used in larger aircraft and helicopters.
Ni-Cd batteries consisted of interleaved electrodes connected by internal current connectors to terminals that pass through the cell cover. Between the electrodes, a non-woven polyamide felt separator keeps the alkaline electrolyte in contact with the active surface. This both prevents short circuits, and allows flow through the electrolyte. The separator system also includes an oxygen barrier made of organic or micro-porous synthetic materials, which, during overcharge, minimizes oxygen recombination to ensure a stable and low overcharge current.
The electrode assembly is housed in a rigid plastic container that allows cells to be fitted side-by-side in a battery case, with each cell equipped with a low pressure vent valve that can be removed to allow water addition. This vent allows any gasses produced during normal operations to be released, while preventing electrolytes from escaping and contaminants from entering.
Lead-acid batteries use one 12-cell or two 6-cell plastic containers to house individual cells that are series-connected through the cell wall. This creates a mono-bloc structure where cells cannot be individually removed or checked. Inter-electrode separation is assured by the use of polymeric or glass fiber mats that maintain the sulphuric acid electrolyte in contact with the active surface.
The main difference between vented and VRLA batteries is the use of higher pressure valves and different separators that, in VRLA, are designed to promote oxygen transfer to maximize oxygen recombination.
Like other aviation components, all battery types require regularly scheduled maintenance checks to ensure their safety. This is typically performed at dedicated battery shops, which possess the specialized equipment needed to safely inspect and repair batteries.
NSN Fulfillment provides a complete list of Aircraft Batteries and Accessories. Click here for Aircraft Batteries and Accessories Catalog
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