Technical paper and presentation created for Oceans 2021 virtual conference

According to the Secretary of the Navy in the Report on Autonomous Vehicle Requirements (AUV) for 2025, “Endurance (how far and how fast can the AUV go, and how many sensors need to be supported)” is one of the four core AUV capability characteristics for the future.  Most oceanographers or subsea operators would agree: going deeper, staying down longer, and/or using more simultaneous and more powerful instruments/sensors are always on their wish list.  This relates directly to endurance.

Endurance subsea most often relates to the amount of and utilization of the power source for the propulsion, instruments, and/or sensors.  While many power sources are available, the mainstream source for subsea untethered vehicles, sensors, and instruments are batteries.  While various battery types exist, the dominant use for subsea applications is lithium primary and lithium ion secondary batteries.

Batteries are electrochemical devices that perform differently at different temperatures and at different rates of discharge.  Thus endurance is affected by both temperature and discharge rate, and even the combination of these within use case operations subsea.  SWE's technical paper outlines test data results and explains the simultaneously measured endurance results and effects of various discharge rates and various temperatures on pressure tolerant lithium ion polymer battery modules.  As such, endurance can be properly planned based on real world use case conditions.  Subsea endurance for AUVS, sensors, or other instruments can be estimated and maximized where possible based on this test information and analysis.

Read the full technical paper or download the presentation below...