RENSEA’s product is the RENSEA battery pack and BMS, developed together with Lithium Storage (Switzerland) as well as a comprehensive high efficiency electric or hybrid electric propulsion systems with EMS (energy management system). The batteries and the BMS were specially designed to meet the specifications for maritime applications. The company offers consultancy, design of complete driveline and installation as well as selling individual battery packs.

RENSEA driveline

A hybrid electric propulsion system combines the strengths of an electric drive system, an ideally designed propeller, a modern battery system and the optimised use of combustion engine with diesel/bio-diesel as a source of energy. For a ship with sails, regeneration adds the benefit of capturing energy generated by the sails during good wind conditions, to recharge the batteries. An in depth study has been done by RENSEA to develop the optimal system that ensures highest possible energy efficiency.

Opal The scooner Opal

RENSEA has now completed two retrofit projects:

The Schooner Opal (picture), owned by North Sailing, is equipped with a 6 * 60 kWh/300v battery packs, a 144 kW electric motor and a specially designed feathered propeller for regeneration. The system is designed so that when sailing, the motor becomes a propeller and generates electricity for the batteries. Opal weights 130 tons and is 24 m long. With 360 kWh battery pack Opal has the capacity to carry out two four-hour whale watching tours on a single charge, with a cruising speed of 7-8 knots. The efficiency of the system as a whole is thus very high.

“Spenna”, also owned by North Sailing was reconstructed in spring 2016 and will be put into whale watching operation on the 1st of July 2016. Spenna has a 4*61kWh/300v battery pack (see picture), a fixed propeller and 109 kW electric motor.

Rensea battery-pack Rensea battery-pack

RENSEA batteries

The batteries are specially designed to fit maritime applications. They are Lithium Iron Phosphate, have high capacity, high temperature range and high reliability. Their rectangular shape can be used to fit all mobile and stationary applications.

Key characteristics of the batteries:

  • LiFePO4
  • IP67 stainless steel battery box – with ventilation system
  • Active BMS
  • TÜV SÜD certified 200ah cells
  • The energy density is 100 watts per kg in finished package and number of charge cycles is 2000 with DoD of 80%. The batteries can withstand 0.5C-1C charging, 3C-10C discharging


The battery design is flexible as they can be packaged in different sizes as for instance 20/40/60 kW packages. Larger and smaller sizes are also available.
What RENSEA can offer:


In addition to maritime batteries, RENSEA can provide EMS (energy management system) and be a partner for designing complete hybrid solutions for different maritime segments.

Sailing in a silent non-polluting way is no longer a farfetched goal. We have a battery-electric solution for various applications, small or large.

For further information:

Jón Björn Skúlason , General Manager
Mobile: +354 863 6510
Grensásvegur 9, 108 Reykjavík, Iceland

Agnes Árnadóttir, Project Manager
Mobile: +47 98469773


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