Gavia has a special battery module which has controlled charge and discharge PC controls built in.   The battery cells are an assembly of LiIon cells fitted to a removable casing installed within the outer module hull section - these cells can be replaced once their usable life has expired.  The battery module has a nominal capacity of 1200 WH which gives Gavia a duration cycle (depending on speed and mission duty sensor cycle) of between 6 and 15 hours.  The battery module is quickly replacable for a recharged module in the field within a possible 10 minute operation.

 GAVIA Battery Module