Team transforms used car batteries into energy storage systems

Researchers from WMG, University of Warwick, have found a way to repurpose used vehicle batteries as small energy storage systems (ESS) for off-grid locations. The repurposed 2 kWh units could be used in developing countries or isolated communities, with enough energy to power a small shop, farm holding or multiple residential homes.

Finding a solution for spent vehicle batteries is becoming more pertinent as the globe shifts to electric vehicles (EVs).

“When an electric vehicle’s battery reaches the end of its useful life, it is by no means massively depleted,” said project lead and WMG Professor James Marco. “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,” Prof. Marco explained.

Although partially depleted batteries may prove useful to others, there are still challenges to overcome, particularly ensuring that the batteries can be used reliably, sustainably and cheaply in remote locations.

Remaining challenges include protecting the lithium-ion cells from overcharge and discharge; determining whether the ESS can be compatible with a variety of other used battery cells and modules from other manufacturers; and ensuring 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 High Value Manufacturing (HVM) Catapult and Jaguar Land Rover (JLR), 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, allowing a working and easily portable prototype to be created, which included:

• 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 available 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.
• Multiple 12 V DC sockets and 5 V USB charge ports.
• The ability to have the 2nd-life module charged via reclaimed laptop chargers.
• A 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,” Prof. Marco said.

The research project was part of the Innovate UK funded Project: 2nd hEVen (2nd-Life Energy Storage Systems) and is supported by the WMG HVM Catapult.

Image credit: © WMG, University of Warwick