Modular Design of Li-Ion and Li-Polymer Batteries for Undersea Environments

Li-Ion chemistry is ideal for undersea environments. The cells are sealed and do not outgas, and the polymer versions can withstand pressures greater than 10,000 psi. This combination results in a battery that is easier and safer to use and one that does not require heavy, expensive pressure vessels. Recent advances in electronic control of the Li-Ion battery and new modular design concepts for construction of complex battery systems have resulted in battery systems that are more robust, more flexible, longer lived, easier to charge and maintain, and safer than their lower density counterparts. These new Li-Ion battery systems can be designed to deliver this energy at high voltages and high currents. Electronic charge control within the battery system allows charging by direct connection to power supplies or constant power sources such as fuel cells and solar panels. The modular design concept for Li-Ion and Li-Polymer battery systems are presented with an emphasis on construction for undersea applications. Key to the modular battery system design concept is the ability to electronically balance all the cells within the battery system automatically without operator intervention. Two different methods are described, which show how electronic balancing of all the cells within the battery system is accomplished. Examples of production battery systems already in service are shown, and systems under development are provided.