Swedish energy tech firm Abtery outlines battery-to-battery high speed electric boat charging

Abtery Technology is a Swedish energy tech company started in 2017 that is exploring and developing low carbon energy solutions, electric drive trains, energy storage systems and charging infrastructure for all transport industries.

The Abtery team is led by made up of individuals who have previously worked with companies like Porsche, Volvo, Faraday Future, Oxis Energy and McLaren, to name only a few.

Under the Abtery banner they have worked with companies like LinearLab (electric motors), RGNT (electric motorcycles) and the Sarvo37, an electric boat with +900kW of power and a 350kWh battery pack.

Battery to battery has DC to DC speed

For obvious reasons they have spent a lot of hours thinking about high speed charging, and have the technical background and experience to imagine and propose ‘out of the box’ ideas.

They recently published a two-part post on LinkedIn with the provocative thought: Want to charge your electric boat in minutes instead of hours? It can be done!

The essence of the idea is using a battery-to-battery solution, rather than charger-to-battery. There are a lot of other things that effect the speed of charging a battery, like the ability of the battery itself to ‘ingest’ the electricity, but the reason (in a nutshell) that battery to battery charging can be so fast and efficient is that it is Direct Current to Direct Current – DC to DC.

Read all about electric boat batteries in the Plugboats Guide

The electricity we use in our homes, offices, and marinas is Alternating Current. So if an electric boat (or EV) is charging from an AC source, there has to be an inverter somewhere – either in the charging station system or in the boat’s system – to convert that electricity to the DC that a battery uses. That takes up time.

Below is the post from Abtery, slightly edited for clarity and to avoid overlap between the two posts, and with some explanatory notes added:

Abtery concept from their LinkedIn post

Jan Voss, CEO of Abtery - author of high speed electric boat charging method
Jonas Voss, Abtery CEO/CTO

Want to charge your electric boat in minutes instead of hours? It can be done!

What electric boats need for wider adoption around the world is remarkably similar to what electric cars needed when they were introduced: super-fast charging capability.

What’s different is that electric boats need that capability delivered in diverse and often, remote, places – on the coast, along rivers, on lakes, etc.

Tesla began solving this problem for the automotive world with the Supercharger concept; design a car to accept fast-charging, and then design – and invest – in a fast-charging network to make the idea a reality. It’s tempting to pursue the same course for the marine sector, but is it really the best solution?

Remote marinas may have limited transmission infrastructure

A lot of marine infrastructure is quite old, basic and very difficult to upgrade compared to infrastructure on the side of a highway. This is especially true of marinas in holiday spots some distance from cities, where connections more often resemble a domestic connection or, at best, a 3-phase connection.

An automotive charging system will only ever be as good as its power feed, so a ‘supercharger’ on a standard-feed electric network is going to be a poor-performing supercharger. It will never be effective without significant (and expensive) investment in the transmission infrastructure that supports it.
(PLUGBOATS NOTE: This is the infrastructure – cables, circuit breakers, switches and transformers of the government or private utility delivering the power.)

So, what if, when there is power of any type on-site, we could deliver fast charging without expensive upgrades to existing electrical infrastructure? Or even better, to sites where geography makes infrastructure upgrades impossible?

Abtery’s solution is battery-based and deployable either as a self-contained onshore unit, as an inclusion in the construction of a new jetty, or even as a floating jetty that boats can dock with, near existing infrastructure.

Charge 126kWh boat from 0-100% in 25 minutes

All we need is a power connection of any type at the site. That could be a standard power connection from the local utility company, or it could be supplemented by renewable technologies like solar and wind. The Abtery solution uses these inputs to deliver DC charging that’s significantly faster than your typical ‘supercharger’.

How fast?

The concept we are developing – based on technology existing now – could charge a 126kWh vessel from 0 charge to 100% charge in around 25 minutes, subject to adequate thermal management on the boat. Smaller capacity vessels could re-charge even faster.
(PB: ‘Thermal management’ is related to the ability of the battery to ingest the electricity. If it comes in too quickly for the battery to ‘absorb’ there will be heat and safety issues.)

This is an obvious advantage for boat owners. The idea of a day on the water being interrupted by several hours of charging is one that will dampen the enthusiasm of many. This solution will reduce charging time from hours to minutes. That’s the dictionary definition of ‘game-changer’.

There are many advantages for marinas, too.

First and foremost – it bypasses the infrastructure investment needed to upgrade power connections from the grid to install an automotive-style supercharger network. If there’s power to the site, then this solution can be installed, regardless of whether the site is urban or remote.
(PB: The on-shore battery would be charged by the AC transmission structure, but there is no need for that to happen quickly, the only requirement is that the on-shore battery (or batteries) have enough power to recharge the boats when they arrive.)

On shore system or floating jetty 

Being a battery-based system, boats charging on it aren’t drawing on a marina’s shore power, reducing peak-hour demand and the long-term maintenance required on network infrastructure.
In terms of design, the battery stacks are modular, allowing the system to be delivered as a standalone unit, or elegantly incorporated into new jetty builds.

The system is also designed as a smart system, with active cell management that maximizes both cell efficiency and longevity. The battery management system can detect a poor performing cell and bypass it without losing any system functionality. This contrasts with simpler systems, where one poor cell will degrade the performance of the entire battery pack.

As a smart system, it can be set up to draw power only when necessary, saving the bulk of its re-charging for evenings, when power is cheapest. And of course, recharging can be supplemented by wind or solar installations at the marina. And as a cloud-based system, operators can enjoy real-time monitoring of the system’s state of charge, and use.

We believe this solution will be a major development in the acceptance of electric boats. Abtery will set up a prototype in Gothenburg later in 2023, which will be used to prove concept capability and hone the user experience prior to being offered for commercial use.


Plugboats thanks Abtery for permission to republish their LinkedIn article

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