This collaborative presentation will describe the experience of one particular ferry owner (Wasaline) which has recently enlarged their originally designed battery system from 2.2 MWh to 12.6 MWh on the Aurora Botnia, which accommodates 935 passengers and has a freight capacity of 1,500 lane metres for trucks and cars. The presentation will feature the integrators and battery supplier explaining the project from installation to integration but also drawing lessons for other projects. The presenters will take questions from the audience to create a must-attend session for owners and operators looking to electrify or upgrade their installed battery systems.