By Kevin Hardy, John Sanderson, Pedram Pebdani, Binh Pham, DeepSea Power & Light
Presented at Underwater Intervention, 2010
Pressure compensated lead-acid storage batteries eliminate the need for heavy, bulky, expensive pressure housings for many underwater applications. They are field repairable, and may be transported by air cargo aircraft. Without a pressure protective housing, power can be delivered within smaller weight and space constraints, with arguable improvements in system safety. The greater weight of lead-acids over other pressure compensated chemistries is often used to counter-ballast the positive displacement of air-filled chambers. Power storage at a remote site allows trickle charging through smaller gage wires when intermittent high current demands are satisfactory.
Pressure compensation means pressure in all interior voids is equal to the ambient external pressure. This is achieved by filling the interior air space of a battery above the plates and electrolyte with an inert fluid, often white mineral oil, with enough excess volume to compensate for effects of temperature contraction and pressure compression. This paper is focused on advancements in the venerable lead-acid battery. The use of other chemistries such as Silver-Zinc and Lithium-Ion, are covered by other authors in great detail in other papers.
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