SubCtech has successfully achieved a major technical milestone in the development of a high-voltage, high-discharge-rate battery and charger system for a customer-defined underwater platform.

As part of the project “The Development of 600 V Nominal High Discharge Rate Battery & Charger for a Underwater Platform,” SubCtech was required to develop a battery system capable of delivering 50 kW of continuous power for a minimum of 45 minutes at an operating temperature of 35 °C. The system features a nominal voltage of approximately 600 V and a nominal energy capacity of more than 40 kWh.

During the electrical full-load test, that took place lately, the battery system successfully delivered the required 50 kW continuous power for more than 50 minutes. This exceeds the customer’s minimum requirement of 45 minutes by more than 11 percent.

Most importantly, the full-load test was conducted at a constant load throughout the entire test duration, as specifically required by the customer. The system was not throttled or power-limited due to temperature-related constraints.

This successful demonstration represents a significant milestone for SubCtech. The achievement marks the first time the company has demonstrated a continuous output of 50 kW from an AUV battery system. At the same time, the project represents SubCtech’s successful entry into the 600 V-class battery segment.

From 35 kW to 50 kW continuous power

The project presented significant technical challenges. At the beginning of the development, SubCtech’s proven battery technology had already demonstrated continuous power levels of up to 35 kW. The new customer requirement, however, called for a substantial increase to 50 kW continuous power, combined with a nominal system voltage of approximately 600 V.

Rather than relying on fundamentally new battery technologies, SubCtech’s engineering team achieved the required performance by further developing and optimizing the company’s established technology platform.

The result demonstrates the capability of SubCtech’s battery architecture to scale to significantly higher voltage and power levels while maintaining the high standards required for demanding underwater applications.

“For the first time, we have demonstrated the truly enormous performance of 50 kW continuous power from an AUV battery system. And we achieved this based on our proven technology, without having to introduce fundamentally new technologies,” says Stefan Marx, CEO.

“The test even ran for more than 50 minutes instead of the required 45 minutes. Under these conditions, this is an outstanding result and a major achievement for the entire team.”

A demanding full-load test

The customer specifically required the battery to maintain its full electrical load continuously for the complete 45-minute test period. The system therefore had to deliver the required power without thermal throttling or a reduction in output caused by temperature-related limitations.

The successful test confirmed that the battery system can maintain the required 50 kW continuous output under the defined operating conditions.

The achievement is particularly significant in view of the demanding operating environment of underwater platforms, where high energy density, power capability, thermal management, reliability and system integration must work together within a highly constrained system architecture.

Technology built on experience

The project also demonstrates the value of SubCtech’s established battery technology and engineering expertise.

The development did not require a complete technological departure from the company’s existing platform. Instead, the SubCtech team successfully leveraged its proven battery technology and engineering know-how to achieve a substantial increase in continuous power output and system voltage.

This approach combines innovation with a high degree of technological maturity – an important factor for customers developing advanced underwater systems where reliability and predictable performance are critical.

“But with the best team – and by that I mean everyone at SubCtech – we had absolute confidence that we could deliver. This result once again confirms our position as a leading global supplier of high-performance underwater battery systems.” says Stefan Marx.

Next steps: FAT and customer-side OSAT

The successful full-load test marks an important development milestone, but the project continues.

The next major step will be the Factory Acceptance Test (FAT) at SubCtech’s facilities. Following this, the system will undergo OSAT at the customer’s site in autumn.

The development program also includes the qualification of the system against demanding environmental and electromagnetic requirements, including qualification testing in accordance with MIL-STD-810G and MIL-STD-461E/F, covering areas such as environmental robustness, shock and vibration, temperature, humidity and electromagnetic compatibility.