Where do used electric vehicle (EV) batteries go after the vehicle they are in reaches the end of its lifecycle, given batteries will still have many charging cycles left in them? Argus spoke with UK EV equipment manufacturer Fellten chief executive Chris Hazell to discuss this simple yet difficult-to-answer question.
What is the core concept behind Fellten's Charge Qube mobile battery energy storage system?
The core idea behind Charge Qube is to provide fast, flexible charging infrastructure for fleets that may not have the space or funds to install permanent charging stations. Our portable charging units are built within containers and can be deployed quickly, allowing fleets to test the EV waters without a long-term commitment. These units are easily leased or returned, offering a cost-effective solution without the need for large infrastructure investments.
Why is this model attractive to fleets?
Fleets often do not own the premises where they operate, making it expensive to install permanent charging infrastructure. Our model solves this by allowing fleets to use their existing power supply and buffer it with batteries. The charging units can handle multiple vehicles at once, whether it is 12 or 20. The key benefit is the flexibility to rent or lease the charging unit and take it with them when they move. This eliminates the need for costly infrastructure that could be left behind, allowing fleets to start small and scale up as their EV fleet grows.
Can you explain how second-life batteries work in these systems?
We use second-life batteries from vehicles that are at the end of their lifecycle. The batteries are not dismantled — we keep them intact with all the safety and management systems still in place. By mounting these batteries inside the charging units, we extend their life and efficiency. The charging units are designed to use lower discharge rates and maintain better temperature control, which means the batteries can last up to 20-25 years. This process helps support a circular economy by giving old batteries a second life.
How do Charge Qubes handle the charging process? Can all the batteries discharge at once?
The Charge Qubes use batteries that are linked in pairs in series, creating an 800V system. While we do not link the batteries in parallel, we use individual DC-DC converters for each battery. These converters feed power into a common DC bus, which allows us to manage each battery separately and control power output efficiently. This design ensures that we can discharge the batteries in a controlled manner, optimising their longevity and performance.
What other applications do you see for your Charge Qubes?
Beyond fleet applications, we are testing the cubes with electric plant machinery, particularly on construction sites. These machines do not always need to return to a central charging station, so bringing charging infrastructure to them is crucial. Additionally, we are exploring how to deploy these units in remote locations with limited grid access, such as desert areas, where charging stations are hard to set up. This versatility makes our charging cubes adaptable to a range of industries.
How are you scaling up production to meet demand for these units?
We are expanding our 30,000ft³ (850m³) facility in Bristol, UK, where we currently manufacture high-voltage battery packs, to include production for Charge Qubes. Right now, we can build around four units a week. We have partnered with container suppliers to ensure we have the necessary shipping containers for our builds. As demand for our charging units grows, we are ready to scale up production and meet market needs.
Are there any restrictions on the types of batteries that can be used in Charge Qubes?
At the moment, we use batteries from EVs such as [US EV maker] Tesla's Model S and Model 3, [Chinese carmaker] BYD and [UK firm] Jaguar, as these are readily available and have sufficient capacity. The battery packs need to be over 50kWh, and we do not mix different battery types in the same charge unit to ensure efficient operation. We are also expanding our battery options, including reverse-engineering systems from models such as [German carmaker] BMW to keep up with demand.
What do you see for the future of energy storage and the electricity grid?
Energy storage will become increasingly vital for buffering the grid, especially as the need for energy distribution grows. While there is enough power, the challenge is how to store and distribute it effectively. One of the main roadblocks is standardisation and the lack of real-time grid management. Current infrastructure is not smart enough to adapt to real-time power demand, but smart grids that can monitor and respond to energy needs will be crucial for a more efficient and flexible system.
Where do you see Charge Qube in the coming years?
In 10 years, we envision Charge Qube units deployed across various industries, from festivals and construction sites to smaller mobile units for plant machinery. We also see significant growth in the US market, where there is still a lot of opportunity to develop EV infrastructure. Ultimately, we want Charge Qube to be a cornerstone of fleet charging solutions and mobile power infrastructure, providing flexible, sustainable energy solutions for a wide range of applications.
