When the batteries in a household electronic device run flat, more often than not they are simply thrown out and replaced. Once an electric vehicle’s (EV) battery pack reaches the end of its useful life – usually around seven to ten years – it will likely be put to significant use elsewhere.
A battery’s service life is determined by the level of degradation it suffers. Over time, its capacity for energy storage will drop slightly, affecting how far it can travel and how quickly it recharges – consider the difference between a new smartphone and one that has been used for a few years.
Once stripped from the vehicle, most battery packs still retain around 70% to 80% of their initial capacity. Considering the cost of producing these packs in the first place, the industry is investigating new ways to put them to use. Private energy storage has become a common second-life application, with locations including corporate campuses and sporting arenas making use of batteries that had once powered a plug-in car.
In November 2016, the Amsterdam ArenA, home to the Ajax football team, signed a ten-year deal to integrate used Nissan Leaf batteries within its power supply. This separate energy storage system distributes power to the stadium and surrounding neighbourhood when necessary.
General Motors has taken similar steps with used Chevrolet Volt batteries to help power the lights at its Enterprise Data Center in Milford, Michigan. Pablo Valencia, Senior Manager of Battery Lifecycle Management at GM, told Automotive World back in August 2015 that a battery could be deployed in a secondary use application “for more than ten years beyond the vehicle, depending on use.” Daimler too has reused batteries from smart fortwo EVs for stationary storage, while Renault has used EV batteries to support high-power charging points.
In addition to corporate settings, used EV batteries could also find use as an energy storage unit at home. Tesla’s Powerwall is an early example, working in tandem with roof-mounted solar panels to store the sun’s energy. Competition in this space is expected to heat up as retired EV battery packs become more widely available. “In areas where a continuous supply of electricity cannot be guaranteed, off-grid systems can help,” said Jürgen Kölch, Research Battery Technician at EVA Fahrzeugtechnik, in a recent Automotive World webinar. “Battery storage can also help where infrastructure is weak,” he added. Examples include emerging markets where the national grid is less developed, or in remote mountain villages.
“These batteries are not produced for second-life applications, and are originally developed for use in a vehicle. However, it makes sense to consider these options if you don’t want to recycle the battery after seven years or so in a vehicle,” noted Marco Moscariello, Head of Product Development at EVA Fahrzeugtechnik.
New and used
While there are numerous examples of battery repurposing today, it remains very early days. Mainstream EVs only hit the market around 2010, and the pool of used battery packs remains thin. As a result, it is difficult to evaluate how they will perform in various roles outside of the vehicle.
“I think it will take another three to five years until we see more second-life battery applications,” said Moscariello. “We have already done some projects in this sector, but right now, we have only been able to analyse theoretical aspects. We will need another five to eight years to see whether these second-life battery packs perform as they should.” According to consultancy IDTechEx, around three million used EV battery packs will be available per year by 2029.
There is also potential for new EV batteries to drive revenue without ever finding use in a vehicle. Moscariello noted that AVL has had conversations with one global automaker to investigate how off the shelf batteries could be sold directly to third parties. “This customer is looking at the possible business case to sell the car battery in its first life for stationary applications,” he said. “This could also reduce the total cost of battery packs for the vehicle itself, and is something our customers are evaluating.”
So far, most second-life applications have leveraged passenger car battery packs, but opportunities should also emerge from the truck and bus segment. Most major brands are developing battery electric city buses, delivery vehicles and even long-haul trucks. These battery packs, explained Moscariello, are potentially easier to work with, and depending on use, have greater capacity for energy storage.
“Many heavy truck applications are 800-volt as opposed to 400-volt, which is a big advantage if you want to use them in a stationary battery application,” he said. “In addition, you do not have to redesign all the components to suit an 800-volt storage system, but right now, there are not many battery electric heavy trucks available.”
Indeed, repurposed heavy-duty batteries are likely some way into the future, given that the first batch of battery electric trucks and buses are yet to be commercialised. Stakeholders are keen to prolong the service life of their batteries and make the most of initial investments, but it will require further investigation over the next few years.