The Operation of DSV “Shinkai 6500” After Converting Main Batteries Yoshinari Ono (Nippon Marine Enterprises, Ltd.) Yoshiji Imai, Itaru Kawama, Hiroyasu Momma (JAMSTEC) 14-1 Ogawa-cho Yokosuka-city Kanagawa JAPAN Fig.1 “Shinkai 6500” and “Yokosuka” Great Voyage in the Pacific Ocean ABSTRACT In March 2004, we have replaced main batteries of DSV “Shinkai 6500” for oil filled pressure compensated lithium-ion battery. After the replacement, “Shinkai 6500” made 59 dives until the end of 2004. The battery worked perfectly as designed during all cruises. There are many advantages in the operation when we compare the lithium-ion battery with the silver oxide zinc battery. Based on the experience of operation in 2004, the difference of the operation between the lithium-ion battery and the silver oxide zinc battery is explained in this report. Since April 2004, the operation of “Shinkai 6500” was entrusted from JAMSTEC to Nippon Marine Enterprises, Ltd. Also in this report, the operation structure after consignment will be mentioned. SUBJECT 1. Operation It has been an obligation for the maintenance of the silver zinc battery system to fully discharge the electricity every 15 dives and to adjust the height level of the electrolysis liquid every 30 dives. The liquid level adjustment requires to be done at a stable condition, which means to be done at harbor. Due to this obligation, the cruise legs were based on a 15 dives period. The new lithium-ion battery system has expelled this obligation, and the operation plan for 2004 had been so constructed to have 25 dives per leg. Also the extra maintenance time has not been required, which had been necessary for the former battery system, the total operation efficiency has increased greatly. Decommission of the "Shikai 2000" in 2002 has affected the "Shinkai 6500" operation in 2004, and many dives were made around Japan near the shore at depths shallower than 2000m. The shallower water depth means the longer bottom time, and the larger power capacity is required. While we were using former silver zinc battery system for dives at depths shallower than 2000m, some dives had to be shortened because of the battery capacity. Further more, the dive on the following may have to be delayed because 12 hours were required for charging the battery. Fig.2 Decommission of the “Shinkai 2000” before and after The new lithium-ion battery system requires only about 6 hours for complete charging, enough to all diving at shallow depth. In 2004, JAMSTEC has conducted a long cruise, named as “NIRAI KANAI”, at the South Pacific Ocean for six month utilizing the support vessel “YOKOSUKA”. 40 dives of the "Shinkai6500" have been included in this plan, and 32 dives out of planned 40 were carried out. The first leg at the South Pacific investigation was not blessed with good sea conditions, and the "Shinkai 6500" could dive only 7 times out of the planned 15 dives. As a result, the "Shikai 6500" could not show up its new sufficient power. At the second leg at the South Pacific investigation, "ShinkaiI 6500" has dove 20 times out of planned 25 dives. Also 13 dives within these 20 dives were carried out in succession (day by day), and the state of the battery was extremely good. Decreases in charge capacity and voltage after charging did not happen, in contrast to our experience with the previous battery. We had been obliged to have serious care on the battery capacity for the previous battery system during consecutive dives, but the lithium-ion battery system has librated us from this obligation. The original plan for this NIRAI KANAI cruise had 2 legs of the "Shinkai 6500" operations. However, the third leg of the "Shinkai 6500" was newly added to the cruise for the recovery of Ocean Bottom Seismometers (OBS), which were not disconnected, from the seafloor by the normal way. In this leg, the "Shinkai 6500" dived 5 times and it had successfully recovered all the planned OBSs, and the sufficient battery power capacity was again recognized. 2. An Operational Advantage in Comparison with Silver Zinc Battery and Lithium Ion Battery * Silver zinc battery requires works to adjust the height level of the electrolysis liquid, but the lithium-ion battery does not require such work. This is almost a maintenance-free system that we had been requiring for. * The decreases of battery capacity and battery voltage did not occur which is usually followed after the repetition of charging/discharging operation. Fig.3 * The "Shinkai 6500" carries two battery systems, and the battery discharge capacities are designed to be the same each other. However, the silver zinc battery system showed sometimes unbalance of the discharge capacities. This means the unbalanced power consumption. The new lithium ion battery system does not show such unbalanced power consumption. Fig.4 * The voltage of the new lithium ion battery system had never fallen down below the prescribed 108V at the end of dive. Fig.5 3. Future Research Legs and Availability The new lithium ion battery system is guaranteed to have a capability of 180 cycles of charge/discharge operations. So far in 2004, it was used 63 cycles, and it is possible to use remaining 117 cycles. 62 dives are planned in 2005 and another 30 dives in the Indian Ocean from January 2006 are also planned. The present new battery system seems to be used without modification for these legs. 4. Future Subject The silver zinc battery system was requested to replace every one-year. The lithium ion battery system needs replacement of every two years. Thus, the lithium-ion battery system is cheaper than the silver zinc battery system on the annual cost base. However, it is still a very expensive battery system. It is necessary to make the price as lower as possible, keeping or improving its high quality. Introduction of the Company: Nippon Marine Enterprises, Ltd. (NME) Following the request from JAMSTEC (Japan Agency for Marine-earth Science and Technologies), NME and JAMSTEC has contracted that NME operates the "Shinkai 6500" in April 2004. So, the manned submersible "Shinkai 6500" is now operated by NME. In October 1981, NME started operation of the support vessel NATSUSHIMA, which is owned by JAMSTEC. We now operate four research and support vessels, one submersible (Shinkai 6500) and two remotely operated vehicles (KAIKO 7000 and Hyper Dolphin). NME intends to continue its intensive support of the profound researches that are concerned with the future of the earth and the life.
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