An Inductive Charging and Real-Time Communications System for Profiling Moorings

Abstract

his paper describes a system for providing power and communications to moored profiling vehicles. A McLane Moored Profiler (MP) was equipped with a rechargeable battery pack and an inductive charging system to allow it to move periodically to a charging dock at the top of a subsurface mooring. Power was provided from a large bank of alkaline batteries housed in two 0.94-m steel spheres. Data were transferred inductively from the profiler to a mooring controller, and from there back to shore via radio and Iridium satellite modems housed in a small surface communications float on an ?L? tether. An acoustic modem provided backup communications to a nearby ship in the event of loss or damage to the surface float. The system was tested in a 180-m-deep fjord (Puget Sound, Washington) and at Station ALOHA (A Long-Term Oligotrophic Habitat Assessment), a 4748-m-deep open-ocean location north of Hawaii. Basic functionality of the system was demonstrated, with the profiler repeatedly recharging at about 225 W (with an overall efficiency of about 70%). Data were relayed back to shore via Iridium and to a nearby ship via the radio and acoustic modems. The system profiled flawlessly for the entire 6-week test in Puget Sound, but charging at the deep site stopped after only 9 days in the deep-ocean deployment owing to damage to the charging station, possibly by surface wave action.