The number of electric vehicles increases rapidly. Now the question arises on what to do with used batteries. Researchers at the University of Warwick have found a way not just to recycle those used batteries, but repurpose them as small energy storage systems (ESS).
Warwick/UK — As part of a Circular Economy for electric vehicle battery systems, the need to find the best way to reuse and recycle vehicle batteries becomes just as intense. Researchers at the University of Wariwick have looked into the use of old batteries for off grid locations in developing countries or isolated communities. The repurposed units, each containing approximately 2 kWh of energy capacity, are able to power a small shop, a farm holding, or multiple residential homes.
Lead author Professor James Marco said that vehicle batteries are not massively depleted when the reach the end of their useful life. It is generally accepted that an EV battery has reached end of life when its capacity drops to 80 % of a fresh battery. While this is no longer enough to satisfy drivers, it remains immensely useful for anyone who seeks to use the battery in a static situation, Marco explained.
While such partially depleted batteries remain potentially very useful to other users there are still challenges to overcome, particularly to ensure that they can be used reliably, sustainably, and cheaply in remote locations. These challenges include:
- How to protect the lithium-ion cells from over-charge and discharge
- Can the ESS be made compatible with a variety of other used battery cells and modules from other manufacturers
- How to keep it low cost and easy maintenance, while providing an interface that is easy to use and understand
The WMG team, at the University of Warwick, set about overcoming these challenges with the help of the WMG HVM Catapult and Jaguar Land Rover who supplied batteries and components from the Jaguar I-PACE, their first all-electric performance SUV. The team designed a new Battery Management System (BMS) and packaging that allowed them to create a working and easily portable prototype ESS which included:
- The use of standard low cost components for control, communication and safety functions. All parts were either sourced from the JLR service department or were low cost components purchased from any electrical retailer.
- The ability to use different modules that could be interchanged within the 2nd-life system without having to recalibrate the whole BMS
- Enough energy for a small shop, farm holding or multiple residential homes
- Multiple 12V DC sockets and 5V USB charge ports
- The ability to have the 2nd –life module charged via reclaimed laptop chargers
- Simplified control system for easy integration and deployment