French group Saft, the world leader in designing, developing and manufacturing advanced batteries for industry, does not often put forward the role it plays in the defence sector but at the recent DSEI exhibition in London its small stand revealed, for those curious enough to ask, that the F-35 Joint Strike Fighter carries a Saft battery and that the group is forging ahead with developments of the Lithium-ion (Li-ion) technology to provide high energy and high power in smaller packages than traditional batteries can provide.
For example, a 24kg Li-ion battery replaces a 90kg lead battery in half the volume and whilst a lead battery lasts for 200 cycles, a Li-ion one lasts 4,000 cycles. Keeping in mind that the modern soldier needs batteries for almost everything, from his radio to his rifle, he uses and then discards many of them; there are an estimated 250,000 abandoned lead batteries lying on the battlefields of Afghanistan polluting the ground and water. Moving to Li-ion technology would greatly reduce the quantities of batteries needed and thus also their polluting factor.
But while Li-ion batteries pack more power than their lead counterparts and have a very long lifetime, they do have a major issue, as Boeing discovered when it bought some from Japanese battery maker, GS Yuasa, and that is that they have a tendency to overheat. They caused a fire aboard a landed Japan Airlines 787-8 on 7th January 2013, followed five days later by an All Nippon Airways 787 that had to make an emergency landing after a battery malfunction warning. These two incidents led the FAA to ground the entire Dreamliner fleet, the first time it had taken such a decision for a line of aircraft since 1979.
Saft concedes that there is a risk to using Li-ion technology but says this risk can be controlled by, for example, modifying some of the chemistry. In the Seanergy® battery system Saft was exhibiting at the show, the battery cells contain phosphate which does not heat beyond 200/250°C, instead of the more usual battery chemicals which can heat up to 700°C. In addition, each of the battery systems has a battery management module (that’s the grey box you can see at the top of the stack of 14 battery modules in the photo) which can identify which, if any, of the modules in the stack is overheating and bypass it. Right at the bottom of the stack is the master battery management module which can switch the whole system off if necessary.
Seanergy can be used to provide hours or days of energy (high energy) to very high power demands of a few seconds of minutes (high power) for floating vessels of all types from warships and cruise liners to offshore vessels and fishing boats.