Development of oil filled pressure compensated lithium-ion secondary battery for DSV Shinkai 6500

Deep Submergence Vehicle Shinkai 6500, owned and operated by Independent Administrative Institution Japan Agency for Marine-Earth Science and Technology (hereafter JAMSTEC, and JAMSTEC was reorganized from Japan Marine Science and Technology Center on April 1, 2004), is the deepest manned submersible in the world. Shinkai 6500 has a depth capability of 6500 m and was developed in 1989 by JAMSTEC, and Mitsubishi Heavy Industries, Ltd. (hereafter MHI). She was commissioned in 1990 with her exclusive support vessel "YOKOSUKA" (length overall; 105 m, gross tonnage; 4,436 GT). Shinkai 6500 has dived 811 times until the end of March 2004. The major dives were carried out in the East Pacific Raise, the Mid Atlantic Ridge, the Indian Ocean and the western Pacific region, including the Mariana Trench and the Japan Trench. She has achieved many fruitful and important scientific results for the science in the world. The original power source of Shinkai 6500 was oil filled pressure compensated silver oxide zinc battery. However, the silver-zinc battery is very expensive, has short life, and is necessary complex work for maintenance. The operators needed to do full electric discharge every 15th dive, and to adjust electrolysis liquid after 30 dives. In order to supply electricity for the Shinkai 6500, two 400Ah battery pods, 800Ah in total, are installed. From 1997, the JAMSTEC Shinkai 6500 operation team, and MHI and Japan Storage Battery Co. Ltd started to develop the 400Ah capacity oil filled pressure compensated lithium-ion battery for Shinkai 6500 main batteries. And we completed development and sea trial in March 2004. The advantage of lithium ion battery in comparison with silver zinc battery is (1) maintenance-free, it is not necessary to do adjustment of electrolysis liquid. (2) long life time, the battery life time increased from 75 times or 1 year, to 180 times or 2 years, and (3) light weight, it is about 100 kg lighter than the silver zinc battery system. We will development and result of operation of introduce the first big capacity oil filled pressure compensated lithium ion battery for the Shinkai 6500.