Sea Technology

JUL 2013

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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is allowed only within the temperature window defned by the cell specifcation, ensuring discharge occurs only within the temperature window specifed by the customer's mission requirements, detecting and preventing short circuits, and allowing high-current pulse discharge to prevent nuisance power interruption. Observing Battery Status SeaSafe Modules and Battery Systems are supported by SeaSafe Observer PC software to monitor their status. Battery status checks can be done after the mission is complete or in real time during the mission. It should be noted that real-time monitoring and an active communications link are for missioninformation purposes only and are not required for autonomous, safe and reliable battery operation. SeaSafe Observer delivers status at three levels: multiple SeaSafe Battery System cases connected together, single SeaSafe Battery Systems case or module level when multiple SeaSafe Battery Modules are in a custom confguration. Module data is concurrently available in raw-data table format for storage or parsing by a separate user-written analysis program. WHOI Modules After more than a year of discussion on ideas and requirements for the ideal pressure-tolerant subsea battery modules, which evolved into the SeaSafe Module, WHOI's frst target application was an under-ice Arctic ROV. WHOI required the battery system to deliver safe and reliable operation at 2,000 meters depth at 88 volts, with 100 recharge cycles, a -20o to +50o C temperature range and 12 hours recharge time. WHOI also needed the module to have internal protection and balancing and external diagnostic information logging. WHOI decided that three modules in a series string would provide the voltage required and nine parallel sets of three series strings would provide the battery capacity needed at that voltage. This is called a 3S9P battery, meaning a three-series-by-nine-parallel confguration of the SeaSafe Battery Modules. The SeaSafe Modules met or exceeded WHOI's requirements, proving 6,000-meter depth capability, far beyond the 2,000 meters needed for the under-ice ROV but in alignment with expected future needs. In addition, the three-series confguration of modules provided 87 volts nominal voltage (3-times-29 volts), or 96 volts peak voltage (3-times-32 volts), meeting or exceeding the 88-volt requirement. Furthermore, the 1,000 cycles of recharge were 10 times the 100-cycle minimum that WHOI requested. Meanwhile, the battery delivered 22 kilowatt-hours, or about 50 percent more than the minimum 15 kilowatt-hours required, and ft within the 36-by-24-by-12-inch space allocation. Meanwhile, yet another application for a battery-powered ROV became fast-track priority at WHOI. Six SeaSafe Modules were deployed in this highdefnition 3D cinematography ROV, with a box frame designed by WHOI to house the modules in the middle of the ROV. While six SeaSafe Modules were used in the original cinematography mission completed in late 2012, future missions plan to carry nine modules. As WHOI works on additional subsea vehicle deployments with SeaSafe Modules, SWE is also engaging other subsea vehicle customers for their vehicle battery solutions for future deployments. Furthermore, as oil and gas subsea production development increases, customers are engaging in design considerations of SeaSafe for subsea primary and backup electrical power. n Leon Adams is the chief sales and marketing offcer at SouthWest Electronic Energy, where he has more than four years of experience in lithium and lithiumion battery applications, product defnition, sales and marketing management, and customer support experience. Previously, he spent 28 years at Texas Instruments, leading embedded processing and digital signal processing product lines for industrial and consumer applications, including battery-powered solutions. He is a member of the Marine Technology Society and has a master's from the University of Texas at Austin and a bachelor's in engineering physics from Murray State University. David White is a senior member of technical staff at SouthWest Electronic Energy in Missouri City, Texas. He graduated from Texas A&M University in 1970 with a bachelor's in electrical engineering. He has been designing state-of-the-art computer, seismic and battery systems for Texas Instruments, Halliburton, Input/Output, SouthWest Electronic Energy and others for more than 40 years. He is a Marine Technology Society member, an emeritus member of the Society of Exploration Geophysicists and a life senior member of the Institute of Electrical and Electronics Engineers. www.sea-technology.com July 2013 / st 23

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