E/F Ellen’s second battery life

Since 2019, E/F Ellen has carried passengers and vehicles between Søby and Fynshav, connecting Ærø with the Danish mainland. Many early electric ferries will soon face the same question as Ellen did: what happens when first-generation battery systems need to be replaced, upgraded or redesigned?

For Ellen, the answer was a complete battery-system redesign on an existing electric ferry with an operating history, a fixed route and a public service to return to. The work went far beyond a standard battery replacement, covering integration with existing vessel systems, new cooling, updated monitoring, approval processes, testing, and crew support. It was delivered in a short time frame.

What began as a first-of-its-kind project is now entering a new operating phase, with a battery system designed to support frequent charging, predictable maintenance and long-term service planning.

Ellen has been an important vessel for Ærø from the beginning, The battery replacement is about keeping the ferry reliable on the route and making sure the technical platform is ready for continued operation for many years to come.

Svend Åge Korup, CTO at Ærøfærgerne

Echandia was selected to supply a 3.2 MWh LTO battery system to replace Ellen’s previous 4.3 MWh NMC system. The new system is designed for a 15-year service life, low degradation and repeated fast charging, with 5 to 6 charging cycles per day. Battery chemistry, thermal management, monitoring and service support were central parts of the operating case.

This project is unique because it was not a newbuild starting from zero. It was a complete redesign and replacement on an existing electric ferry, carried out within a short time frame. Our role has been to support Ellen’s next operating phase with a battery system built for frequent fast charging, long lifetime and predictable performance.

Torben Mørch Sørensen, Sales Director at Echandia

The replacement required close cooperation between Ærøfærgerne, Echandia, Valmet and Danfoss, with support from Søby shipyard. Ellen was also upgraded from water cooling to air cooling, with new monitoring technology and more measurement points on board. That gives Ærøfærgerne better visibility into system performance and creates a stronger base for service planning over the next operating period.

During the first days back in service, teams from Ærøfærgerne, Echandia and project partners remained on board to monitor the system, support the crew and handle adjustments. Ellen will now return to operation between Søby and Fynshav.

The project points to the next stage of electric ferry development: upgrading existing vessels, redesigning systems and keeping proven routes in reliable operation.