Batteries, like those of electric vehicles (EV), gradually degrade over time as they are frequently charged and power vehicles (discharged) over time and will fall below 70-80% of their initial capacity which is below what a EV requires. During the next few decades, the strong uptake of EVs will result in a huge volume of batteries that will gradually reach their useful life. To put this in perspective, nations like the United States currently use a similar amount of electricity storage over a full year, so this is a lot of batteries with energy-storage potentials. However, although these batteries don’t meet the minimum requirements for an EV they still have useful life. Finding applications for these still-useful batteries can create significant value and ultimately even help bring down the cost of storage.
What are the minimum requirements of a EV battery before it becomes second-life?
EV Batteries have a tough life. Subjected to extreme operating temperatures, hundreds of partial cycles a year (charging and discharging partially), and changing discharge rates, lithium-ion batteries in EV applications degrade strongly during the first five years of operation. EV batteries are designed for approximately a decade of useful life in most cases yet, these batteries can live a second life even when they no longer meet EV performance standards. EV performance standards typically include maintaining 80 per cent of total usable capacity and achieving a resting self-discharge rate of only about 5 per cent over 24 hours (e.g. a sitting battery will still have some chemical reactions which causes the small discharge). After remanufacturing, such batteries are still able to perform sufficiently to serve less demanding applications, such as stationary energy-storage services.
How long do EV batteries typically last?
It depends but from one 2020 study it was as much as 8 years or 100,000 miles but there were many factors to consider.
The lithium-ion battery packs used in electric cars are similar to those used in cell phones and laptop computers, only they’re much larger. They’re far different than the heavy lead-acid batteries used in conventional cars and have a higher energy density than rechargeable nickel-metal hydride batteries. They’re also less prone than other battery types to lose their charge when not being used. EV battery packs generally contain a series of connected individual cells, instead of a single massive unit.
While an electric vehicle’s battery pack will tend to degrade slightly with each charge and discharge cycle, it’s an extremely gradual process. For example, according to data compiled by the organization Plug In America, the battery pack in a Tesla Model S will only lose around five percent of its original capacity over the first 50,000 miles, with the rate of depletion actually slowing down from there.
In a recent Tesla discussion thread on Reddit, most of those owning a Model S reported losing only a few percentage points of the car’s initial battery capacity after several years of use.
On the downside, electric cars kept in the hottest climates can be expected to lose battery capacity a bit quicker than those living in more temperate areas. Extreme heat is the enemy of lithium-ion chemistry, which is why many electric cars come with liquid-cooled battery packs.
Also, older electric cars having relatively short operating ranges may suffer quicker deterioration. That’s because draining most or all of a battery’s charge on a regular basis tends to cut into its capacity more quickly over time. That’s far less of an issue with today’s longer-range models that are typically driven for a fraction of their available capacity on a daily basis and are merely “topped off” at night.
Excessive use of public Level 3 DC Fast Charging stations (they can bring an EV up to 80 percent of its capacity in as little as 30 minutes) can also take a toll on a battery’s long-term performance. That’s because the faster an electric car is charged, the hotter it becomes and, again, that’s not battery friendly. However, a study conducted by the Idaho National Laboratory concluded that the effect isn’t particularly pronounced.
The INL tested two pairs of identical 2012 Nissan Leaf models, with one set using 240-volt Level 2 home charging and the other exclusively relying on DC Fast Charging public units. After each was driven 50,000 miles, the difference between the Level 2 and Level 3 vehicles’ diminished battery capacities amounted to just four per cent.
Why can’t batteries be used 100%?
A battery, even when not in use, loses its capacity over time due to internal leakage. Battery manufacturers quantify this leakage as self-discharge per month. For example, a 300 mAH battery with self-discharge per month of 0.5% loses 1.5 mAH of its capacity after one month and hence the reason why there must be a minimum % threshold. The EV battery shelf life is defined as the longest time a battery can be stored before its capacity falls below 80% of its nominal.
Whilst batteries are capable of operating in an ambient temperature of 35°C, with occasional excursions to 40°C, these high temperatures are avoided, as they lead to greater evaporation of water from the electrolyte and a significant reduction in service life. In general, you will usually need a new battery after three to four years. But that’s where second-life batteries play a significant role.
What are second-life batteries used for?
Reuse can provide the most value in markets where there is demand for batteries for stationary energy-storage applications that require less-frequent battery cycling (for example, 100 to 300 cycles per year).
Based on cycling requirements, three applications are most suitable for second-life EV batteries: (a) providing reserve energy capacity to maintain a utility’s power reliability at lower cost by displacing more expensive and less efficient assets (for instance, old combined-cycle gas turbines), (b) deferring transmission and distribution investments, (c) and taking advantage of power-arbitrage opportunities by storing renewable power for use during periods of scarcity thus providing greater grid flexibility.
Examples of second life battery uses
Nissan was one of the first major automakers to pilot second-life EV batteries in a grid-scale storage installation in 2015. That same year, BMW tested used batteries in demand response events during an 18-month pilot project in partnership with Pacific Gas & Electric.
Also in 2015, Daimler AG announced to build a 13-megawatt-hour second-life battery storage unit at a recycling plant in Lünen, Germany. In September of 2016 the plant was started up and according to figures from the German Ministry for the Economy and Energy (BMWi), 40 to 45 percent of power consumed in Germany is to be generated from renewable resources by 2025, increasing to 55 to 60 percent by 2035.
Daimler subsidiary Mercedes-Benz Energy teamed up last year with Beijing Electric Vehicle, one of China’s largest EV makers, to build an energy storage system that uses retired EV batteries.
While it hasn’t ventured into the stationary storage space directly, American electric truck startup Rivian designed its battery packs from the outset to make end-of-life repurposing as easy as possible. Electric bus manufacturer Proterra took the same approach.
What is the price of a second life battery?
The cost of Li-ion batteries is down by 80% from $1000/kWh in 2010 to $200/kWh in 2018 and might reach $100/kWh by 2025-26. The potential value of second-life batteries is impacted by how the batteries are designed and used in their first life in the electric vehicles, how they are collected and used in second-life applications as well as the value of recycling. Right now the cost of second live EV batteries range from $51 to $1500 depending upon the models. But it is predicted that by 2030, second-life battery capacity will hit over 275GWh per year which presents huge opportunities for energy storage. However, many technical, economic and regulatory challenges exist that might make it difficult for companies to profit from second-life batteries.
Startups with second life battery solutions
Solutions are within reach, with a growing group of technology startups and major automakers working to advance the second-life battery segment as EV sales continue to increase.
1. Fortum
Fortum, a European firm, is piloting second-life solutions for batteries, where used EV batteries are used as stationary energy storage after they are no longer fit for their original purpose. Fortum, Volvo Cars and Cleantech company – Comsys came together to create something new from something old. The three companies created an innovative solution combining used batteries from electric vehicles into one great battery. The solution, installed in Landafors hydropower plant, enhances the plant turbines’ capability to regulate the grid and extends their lifetime.
Company’s Website – https://www.fortum.com/
2. Connected Energy
Connected Energy, a specialist in award-winning energy storage solutions that give a second life to electric vehicle batteries, has commissioned its largest ever second-life battery energy storage system, the E-STOR. Using Renault batteries, these systems are a fundamental part of harnessing the circular economy to provide industrial-scale energy storage.
Company’s Website – https://c-e-int.com/
3. Nunam
While this startup is not working particularly on electric vehicles, they collect old batteries from e-waste dealers and distribute their repurposed energy storage systems to street vendors and small shopkeepers. Giving batteries a second life has a long-standing impact on the country’s energy plans.
Company’s Website – https://www.nunam.com/
The nascent second-life battery market also needs a steady battery supply, customer demand and access to funding in order to be successful.
Conclusion
Reused or “second-life” lithium-ion batteries still have a lot of juice left in them, but so far the concept of using these batteries in stationary applications has yet to gain real market traction. New research, growing automotive industry interest and an expanding startup ecosystem suggests that that could now finally be changing.
Error SendFox Connection: