The Formation

SubCtech GmbH based in Kiel combines marine engineering, marine research and offshore technologies. With roots back to the 80s, international connections to research institutes and industrial cooperations, highly innovative subsea products are developed at the Kiel location. The company was founded in early 2010 by Dipl.-Phys. Stefan Marx. With his experience in science (CAU Kiel, GKSS/HZG Geesthacht) and many years of corporate experience, as well as a highly motivated team of experts, projects with CO2 monitoring systems and Li-Ion batteries were already successfully implemented in 2010. The company is still 100% privately owned and employs 38 people in 2021.


The Evolution

With a consistent focus on international markets and customer requirements, the company grew steadily from three employees at the very start to 38 today. Monitoring systems for water parameters and climate research are now used worldwide. The miniaturized version OceanPack RACE® became famous with Volvo Ocean Race and Boris Herrmann during the Vendée Globe. Li-Ion batteries are used in underwater vehicles (AUVs or drones) and in offshore Oil+Gas applications (All-Electric).

Especially the close cooperation with our clients, a highly motivated and very well trained team and a high flexibility, as well as the cooperation with leading research institutions guarantee a dynamic, efficient and innovative realization of their goals.


In the MAUS project, Li-Ion technology is being further developed for the use on underwater vehicles. The goals are:

  • Standardized Li-Ion based battery modules that can be used for different vehicles and mission profiles.
  • Safe Li-Ion batteries with highest power density in minimal space
  • A battery management system that allows configuration of system behavior and automatic tracking of battery parameters
  • Creation of a standardized interface for communication and interaction with the higher-level control systems
  • Energy management for efficient use of the battery with regard to the mission tasks, recording of operating parameters and calculation of the possible mission duration

Development of an intelligent charging device that enables charging in water, minimizing turn-around times.