22.–23.05.2024 #polismobility

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Power pack for ice adventures

The battery in eSleds

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Every year, millions of tourists are drawn to the picturesque snowy landscapes of Lapland. Many of them are travelling on electric snowmobiles - for example on the eSled from Aurora Powertrains. The electrified snowmobiles are environmentally friendly and quiet, but the built-in battery has to withstand a lot.

Snowy landscape with fir trees, two snowmobiles and two people in rear view with ski clothing looking at the northern lights on the horizon.

© Aurora Powertrains/ Farasis Energy

Electric snowmobiles are environmentally friendly and quiet, but operating in temperatures as low as minus 40 degrees Celsius, combined with snow and moisture, places high demands on the battery. Not only can it lose performance, but it also ages more quickly. To counteract this problem, Aurora Powertrains relies on pouch cells from Farasis Energy for its eSled snowmobile.

In Lapland, where freezing cold temperatures and snow-white landscapes attract millions of tourists every year, snowmobiles are a great way to explore the region. The company Aurora Powertrains, based in Rovaniemi, the capital of the Finnish region of Lapland, has developed the eSled model for this purpose. Matti Autioniemi, founder and CEO of Aurora Powertrains, quickly realised that a battery that works reliably in these conditions is not easy to find. The company therefore decided to develop its own battery module to meet the special requirements. "We knew from the outset that we needed a customised module that would make optimum use of the limited space in a snowmobile and withstand the extreme environmental conditions," explains Autioniemi.

Angular instead of cylindrical: the choice of battery cells

When searching for suitable battery cells, it turned out that cylindrical cells, although they are available in high quality, are not suitable for installation in a snowmobile. They have too small a surface area to dissipate heat quickly and efficiently. In order to fulfil the performance requirements, the limited space had to be optimally used and a high energy density had to be achieved. In addition, the battery technology had to withstand wet, cold and vibrations. The snowmobiles were either on tour in the winter landscapes of Lapland or were being charged. Due to the demands of off-road use, the battery technology had to be cooled despite the low outside temperatures.

A different solution therefore had to be found. The company was looking for compact cells with a long service life, temperature resistance and high energy density. Aurora Powertrains decided to use the unidirectional P32 pouch cells. These cells have a rectangular shape and can expand optimally in the limited installation space. The largest battery variant of the eSled consists of six modules and has an energy capacity of 21 kilowatt hours. This enables a range of around 100 kilometres. The use of cylindrical or prismatic cells would not have achieved these values in the prototypes.

Another advantage for Aurora Powertrains was that its own thermal management solution could be used. This enables smooth operation at temperatures as low as -40 °C. An active fluid circuit equalises temperature differences within the module. In addition, heating foils were integrated on the floor to preheat the cells to an optimum 25°C. Although tourist groups generally do not cover more than 25 kilometres during the tours and are on the road for a total of around 3 hours, the high energy density and the associated maximum range of 100 kilometres provide a sufficient safety reserve in remote areas of Lapland.

The future of eSleds

Aurora Powertrains aims to have 600 eSleds rolling off the production line by 2025. The whisper-quiet snowmobiles open doors to sensitive areas such as national parks and transform tourist excursions into emission-free adventures. "Imagine gliding through the breathtaking landscape of the far north, listening to the tour guide's explanations, observing the wildlife undisturbed and leaving no ecological footprint. That's the magic of electric snowmobiles," enthuses Matti Autioniemi. Although the environmentally friendly alternative in the tourism sector fulfils all expectations, there are still challenges on the way to a fully electric future. Over the next five to ten years, the technology will need to be further developed so that specialised snowmobiles for use in deep snow or racing can be replaced by an electric version.