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Batteries for your boat (consumption)

The next generation of powerful, safe and cobalt-free lithium batteries

Fully digital

Smart control with your smartphone via Bluetooth®

Fast charging, several days of use

From 0-100% in 2.5 hours with shore or motor power

Lower weight, longer lifespan

Up to 8 times lighter and longer life than traditional lead-acid batteries

Harbour, Croatia.

Power your devices for days

With batteries from Undine, you have enough power on board to keep your appliances on for days. You can safely have the light on, keep the food and drinks cold in the fridge, charge your phone and use the navigation at the same time.

About the battery

  • Specially developed lithium consumer battery for maritime use
  • 100+ hours of active use at normal power consumption (4 amps)
  • Low weight, only 34kg
  • Size (LxWxH): 48,3×22,7×24,1cm
  • Replaces up to 8 ordinary lead/acid batteries directly
  • 420Ah@12V – 5.3kWh
  • Continuous energy: 150A. Peak load: 300A
  • Bluetooth® Low Energy (BLE) connection to iOS/Android
  • Based on Iron Phosphate (LFP/LiFePO4), Grade A cells, 100% cobalt free
  • Free delivery in Denmark
  • 3 year warranty

Fully digital

Easily monitor the capacity of your batteries

Undine’s consumer batteries can be controlled 100% digitally with your smartphone via Bluetooth® Low Energy. With the Undine App, you always have an overview of power consumption and charging. The Undine App is available in both Google Play and App Store.

Built-in display

You can also always see exactly how much power is left on the intelligent display of the battery itself and control consumption directly using the buttons.

Drawing of the battery content


Safely leave safety to the BMS monitoring

The chemical composition of the Undine lithium batteries means they can withstand high temperatures and are far more stable and safe than other batteries.

Safe operation and optimization of performance and lifetime

The digital monitoring system, BMS (Battery Management System) ensures that you can safely sit back and enjoy sailing. The sensors built into the system constantly monitor overcharge, undervoltage, overcurrent, temperature, potential short circuit and imbalance between the battery cells. In harmful conditions, the BMS automatically disconnects the battery. BMS monitoring also protects your battery from degradation and uneven discharge, which can otherwise shorten its life.

Why lithium batteries

Our lithium batteries weigh 1/8 and take up just over 1/5 compared to traditional lead-acid batteries. On top of that, they have longer life, higher efficiency, greater safety and faster charging and discharging.

One large Undine (consumption) battery replaces lead-acid batteries as shown in the picture *)

Better size, capacity and durability

Undine batteries have an extra long life with up to 4,000 charges and still 80% capacity left. They deliver up to 50% more and stable energy, where lead-acid batteries quickly lose energy during heavy discharge, lithium batteries, thanks to low resistance, have minimal losses, continuous energy throughout the discharge.

Lasts 5 days on the water

With one large Undine battery you can have the fridge on for 22 days, GPS on for 18 days, lights on for 35 days (3 LED bulbs) and the heat on for 16 days. If you use all devices at the same time, you have enough energy for 5 days without recharging.

Old LeadAcid batteries vs Undine Batteri


Easy to install

Undine lithium batteries are easy to install with screw terminals for Ø 8 mm bolts, which is the most commonly used type. If your old boat battery is fitted with cable lugs, these are simply removed and screwed onto the new battery. If you have cable clamps, simply switch to cable lugs instead.

Get help installing

You are always welcome to contact Undine. We are happy to help with guidance and installation. You are also welcome to contact our business partner, Skovshoved Yachtværft, who also helps with the installation of batteries.

Battery close-up


We set high standards right down to the battery cell

Undines long-life, cobalt-free lithium batteries based on iron phosphate are developed, tested and assembled in Denmark. This allows us to follow the process from the smallest battery cell to the finished battery, ensuring that the batteries meet our requirements for maximum safety, capacity, performance, stability, sustainability and lifetime.

The battery cells are produced by a subcontractor who carefully manufactures them to our specifications, and we carry out regular quality inspections.

The battery systems are assembled using advanced robotic technology.


Batteries with consideration for the environment and the climate

We all have an interest in striving for more sustainable and climate-friendly solutions, including when it comes to boat batteries. Undine’s lithium batteries are distinguished by being free of environmentally harmful and flammable substances such as cobalt. The lithium battery’s exterior is made entirely from recycled ABS scrap. ABS plastic is a safe, recyclable and non-toxic material. In addition, the batteries’ electrodes, wires and cables are reusable.

The longer the lifespan, the more sustainable

When you choose batteries with a long lifespan, you help reduce pollution and consumption of resources. Undine’s lithium batteries are a more sustainable choice than, for example, lead-acid batteries, which typically have only 300-500 cycles. The Undine lithium battery has a life cycle of 4,000 charges, after which there will still be 80% capacity left. 

Frequently asked questions

Our batteries are 12v. If you already have a 12V electrical installation they can be used (most boats do). If your boat has 24V, you can contact us for delivery options.

Generally the battery can be charged with an existing lead/acid charger. But we recommend buying a fully compatible lithium charger. We do this because lead-acid battery chargers cannot fully charge the battery and charging profiles can be different. By purchasing a lithium charger, it is possible to charge the battery faster.

Undine’s lithium batteries have a cycle life of 4,000 times, making them a more sustainable choice than for example lead acid batteries, which typically only have 300-500 cycles.

The battery pack can be expanded in capacity, but not in voltage. This means that you cannot go from e.g. 12V to 24V.

If the generator is from an older date, we recommend our charge limiter of, for example, 40A so that the generator does not get too hot and burn out. One of the advantages of lithium batteries that it can be quickly charged, but that the power source must also be able to keep up.

If there is physical space, it is possible with the help of our mounting straps to make the battery firm and seaworthy. The size of the different batteries can be seen on the product pages.