The start of construction on the first Class 126 frigate is getting closer; Preparations are in full swing. In order to ensure a self-sufficient energy supply for the ships, a team from the Federal Office for Equipment, Information Technology and Use of the Bundeswehr (BAAINBw Federal Office for Equipment, Information Technology and Use of the Bundeswehr) the battery technology used.

The state-of-the-art ships of Frigate 126, the first of which is scheduled to be delivered in 2028, have a sophisticated energy concept. In addition to four power generation units, there are also two shaft generators installed that can generate electrical energy. This structure is supplemented by four battery sets, which are equipped with special lithium batteries.

What sounds so unspectacular has a lot of charging power: the batteries used on the F126 can store as much energy as 14 commercially available electric cars. A key advantage of the technology used is the longevity of the batteries. This feature is of particular importance for use on the frigate because the energy supply concept stipulates that load peaks that occur in the power supply should be buffered by the energy stored in the batteries. This ensures a constant energy supply.

The batteries are charged as long as the power generation units are not yet at full capacity. This also increases the efficiency of the entire energy supply on the frigates. In regular operation, they are only discharged to such an extent that enough energy is available at all times to safely supply the ship even if the electrical energy fails.

No technical system offers only advantages. Due to the design of the lithium batteries used, there is an increased risk of fire on board.

The BAAINBw group S8, which is responsible for project implementation Federal Office for Equipment, Information Technology and Use of the Bundeswehr is therefore working together with a team from the Defense Technical Office for Land-Based Vehicle Systems, Pioneer and Troop Technology (WTD Defense technical department41 ) and the Fraunhofer Institute for Chemical Technology (ICT) are working intensively on the safety of the battery modules intended for the frigates.

While at WTD Defense technical department41 In addition to carrying out experiments that test the service life of the battery modules under realistic operating conditions, a series of tests to investigate the safety of the batteries has been taking place at the ICT since August 2023. The aim of the tests is to assess the risk of so-called propagation when a battery cell overheats within the battery module.

What does that mean? During propagation , the overheating cell transfers so much energy to the neighboring cells that they are also stimulated to overheat. This creates a chain reaction in the battery system. What is crucial, however, is whether this process continues or not. If the neighboring cells do not react or can reduce the resulting excess pressure in a controlled manner, such an incident can be easily controlled with appropriate safety measures.

Since a frigate is designed for threat scenarios in which major damage to the batteries can occur, the battery rooms are also equipped with specially adapted fire extinguishing systems and structural room security measures.

For example, a suitable exhaust system that detects escaping gases and can quickly remove them is intended to ensure that no explosive gas mixture can form within the battery room. To ensure that, in the best case scenario, this system does not have to be used at all, the battery modules are monitored accordingly and immediately disconnected from the network in the event of any abnormalities.

The first experiment carried out to investigate the propagation risk was promising, but also showed additional potential for optimization, reported those responsible at Fraunhofer ICT. No propagation was detected. Only the extremely overloaded cells were destroyed and two of the surrounding cells were slightly damaged. Further experiments are already being planned.

Those responsible are pleased that the F126 project has once again reached a milestone in the development phase. An important step on the way to the start of production of the frigate.