Qualification of AGM lead-acid batteries for long-term subsea deployment

Deployed cabled observatories are providing continuous power to a variety of new subsea and surface instruments. Higher power instruments, like vertical profilers and small ROVs have become possible, but challenge the power feed systems with their large peak power demands. Load management solutions need to be developed to extract the most utility out of the available power. One option for load leveling is the use of subsea battery banks. This also provides uninterruptable power supply (UPS) functionality. Absorbed Glass Mat (AGM) lead-acid batteries are routinely used subsea in low-power, pure discharge applications. Longterm stationary subsea power delivery requires adapting current lead-acid technology from discharge-only, to charge-and-discharge at depth operation. The increase in scale and scope for lead-acid technology requires an understanding of the effects of pressure and oil compensation on the batteries and how to best configure the batteries to ensure long and reliable service in the subsea environment.