WMG researchers convert used EV batteries into small off-grid ESS units
13 August 2019
Researchers at WMG, University of Warwick, have repurposed end-of-life electric vehicle batteries as small energy storage systems (ESS) for off-grid locations in developing countries or isolated communities. The repurposed units, each containing approximately 2kWh of energy capacity, will be able to power a small shop, a farm holding, or multiple residential homes.
When an electric vehicle’s battery reaches the end of its useful life it is by no means massively depleted. It has simply reached the end of its useful life in a vehicle. 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.—WMG’s Professor James Marco, lead researcher
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 set about overcoming these challenges with the help of the WMG HVM Catapult and Jaguar Land Rover, which supplied batteries and components from the Jaguar I-PACE, its 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.
This is a great result that not only provides a highly efficient repurposing solution for automotive batteries but which could also change lives in remote communities. We are now looking for support to allow these new units to be further developed and tested in remote or off grid locations.—Professor James Marco
The research project was part of the Innovate UK funded Project: 2nd hEVen (2nd-Life Energy Storage Systems) and is supported by the WMG High Value Manufacturing (HVM) Catapult.