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Subsea Batteries


Simplify your system design with SubCtech batteries: ⇒ lower your CAPEX
Use SubCtech batteries: ⇒ lower your OPEX.

High power underwater Lithium-Ion rechargeable batteries (Li-Ion PowerPacks™) have proven themselves as suitable offshore power supply systems on many occasions. This type of Li-Ion cells is used in aircrafts, space vehicles as well as naval applications. The sophisticated battery management system (SmartBMS) guarantees highest performance without any risks, allowing the use of high-power Li-Ion systems in offshore and other rough environments.


  • Subsea electric systems, „All Electric“
  • Monitoring stations


  • High safety: multiple independent system monitors. Handy blocks of low energy, low weights and low voltages
  • High reliability: optional redundant design with at least 50% capacity in all circumstances
  • Minimum costs: long operating life, short charging cycles
  • Simple handling: only 2 buttons to control the charging unit. Charging without opening the battery, simply underwater
  • Easy maintenance: little time and costs
  • Highest rated power: Very high capacities with optimized weight and size lead to significantly expanded operating times


  • High-power up to 30+kW
  • High-energy up to 100+kWh
  • Voltage range 14,4V up to 400+V
  • Currents up to ~100A
  • Long life up to 30 years
  • Battery divided into portable blocks, approx. 30kg each, low voltage
  • Integrated SmartBMS™ controller
  • Data interface RS-232/485, galvanic de-coupled, ASCII NMEA-0183 or MODBUS RTU
  • Simple installation and operation
  • Design, capacity and mechanical customization for your project


  • ISO 13628-6 or API17F,N MIL-STD 810G or GL VI for industrial applications
  • EMC tests according to MIL-STD, DIN-EN, GL
  • Production according e.g. IPC-A-600/610 class 2 or 3

Product overview:

SEM with Li-ion buffer battery and subsea charging Manifold with Li-Ion battery and ISO ROV switch
Li-Ion battery 280V (4 x 70V) – series production Li-Ion battery approved according MIL-STD 810G, ISO 13628:6, API17
19“ Rack PowerCharger with touch-screen, 2 x 3kW 19″ PowerCharger diagnostic screens to optionally check single Li-Ion cells


Leading Li-Ion technology delivers re-chargeable high-capacity batteries. The Li-Ion PowerPacks™ provide high currents of about ~100A and high tension of up to 600V.

The batteries are set up out of blocks of approximately 30kg and 48V each. That allows an easy handling and provides protection for the user at the same time.

The integrated Battery Management System (SmartBMS) monitors the battery without interaction of the operator. For critical applications, such as the AUV drives, the Li-Ion PowerPack™ are designed fully redundant and with minimum EMV signature. Diagnostic messages are transmitted in ASCII; with a galvanically isolated bus, the internal components and the chargers are controlled.

The Li-Ion PowerPack™ are designed to be fully redundant to guarantee that still 50% of the remaining capacity would be available in the event of a fatal error. Due to that feature missions can be brought to a regular end.

The Li-Ion PowerPack™ is monitored multiple times. Each battery unit has its own controller (the so-called BMS-Slave), which is in turn controlled by a respective so-called watchdog. In the event of an error, the Li-Ion PowerPack™ (or just one half in case of a redundant construction) is switched off.

The BMS-Master of Li-Ion PowerPack™ actively controls the chargers. After charging, an automatic balancing of the individual cells takes place to compensate different charging statuses and to ensure optimal performance.

Despite this sophisticated technology, the operation is as simple as ever – with only two „Charge“, „Test“ and „Storage“ buttons to test and prepare for storage. These functions are also accessible via a touchscreen, where informative menus can also control each individual cell.