When is the best time to recycle a battery? Circunomics, a start-up company, has based its business model on vehicle batteries. Rather than recycling them once they are no longer suitable for driving a car, Circunomics uses them for a second-life application as energy storage. Automotive and battery manufacturers can use Circunomics’ digital marketplace to sell their used or surplus batteries, modules and cells to customers from the energy industry.
In this interview, Marius Vogt, Head of Sales at Circunomics, reveals how the company uses AI to assess a battery’s value throughout its life cycle, and to forecast when its first-life use ends.
Back in 2018, while still working for a digital agency, mediaman GmbH, Felix Wagner and Jan Born came up with the idea. The agency had been tasked by an automobile manufacturer with creating a report on the circular economy of a particular electric vehicle. At the time, there was little data to be found on resource-conserving and efficient battery recycling, prompting Felix Wagner and Jan Born to investigate the issue in more depth, and deciding to fill the market gap with their own start-up. They started developing concepts and searched for answers to questions such as: What options are there for using batteries once they are not used in a car anymore? How do you determine whether a battery is suitable for a second-life application? Which recycling methods make sense? These were the questions that created the foundation of our work today, developing sustainable solutions for the circular battery economy. It soon became clear that the challenge is huge, and that the business with second-life and recycling is much more than a gap in the market – it is an immense task with massive potential.
This is where our battery analysis tool comes in. Today, during the first life of a battery, in a passenger car for example, manufacturers collect and store extensive and detailed data. We compile this data in our cloud-based software, so that our analysis tool can accurately determine the battery’s state of health. We then use a digital twin to calculate how the used battery will behave during its second life. This allows us to give recommendations to our customers, such as a manufacturer of energy storage systems integrated in large photovoltaic installations, as to which batteries offered on the digital marketplace are best suited for their project. Depending on the area of application, this gives batteries an additional five to eight years of service life, a considerable extension, before they are sent to a qualified recycling process.
Ideally, we would like to have access to the data as early as during a battery’s first life. This means that we will not want access to a user’s specific driving data – we just want to access the data in the battery management system (BMS). This would allow our analysis tool to find out how long a battery’s second life will be, and what its value will be, as early as during the first life. This is not about interfering in the battery’s operation, but about monitoring it and giving the user tips on how to use it more economically. Based on the personalized consumption data, we can then forecast a battery’s service life.
The gist of our work is bringing together all industry partners involved in a battery’s service life with the aim of reusing batteries. Energy storage systems, from small residential storage systems to large commercial storage systems, are the most common areas of use. They provide grid-balancing services or peak shaving.
We have to start by getting to know the battery through the data collected. This is done by an algorithm that understands battery aging and behavior. The more data we have, the clearer the picture and the more accurate the analysis of the state of health and the subsequent forecast for its’ second life.
Our algorithm is based on an electrochemical model filled with data from the battery’s first-life use. This is compared with data collected in our own laboratory, where we run a generic ageing process by subjecting the batteries to high strain, testing them under different C-rates and temperature conditions, and using that data to optimize our AI-supported software. The C-rate tells us how fast a battery is at taking up and providing energy, which indicates charging time, performance and service life.
This method helps us achieve up to 97 percent accuracy, with a maximum deviation from laboratory analyses of just 3 percent. Once we have done this, we turn to our platform for “battery matchmaking”, forecasting for which second-life application a battery is suitable. This could be as storage in a wind or solar park.
During its lifespan, a vehicle battery will be subject to various types of stress: Fast driving, accelerating, charging at various power levels and extreme temperature fluctuations stress a battery and may speed up ageing. Once a battery is no longer suitable for the demanding load cycle of a vehicle, alternative usages can be considered – and that is exactly where energy storage comes in. Vehicle batteries are designed for high C-rates. The C-rate during discharge is typically between 3 and 5 C, during charging between 1 and 2 C. Let me explain: A C-rate of 1 C corresponds to a charging/discharging time of one hour, and a C-rate of 5 C corresponds to a charging/discharging time of around 12 minutes. Such high stress leads to faster wear.
In an energy storage system, such as in a solar farm, the situation is different. Energy charge and discharge is much more regular, and the C-rate is just 0.5 to 1 C, leading to considerably less wear than when a battery is used in a car.
Vehicle batteries are designed for high performance, and that is why they are excellently suited for reuse as energy storage. They can work reliably for several more years by helping to store and provide renewable energy efficiently.
Our AI creates billions of images and analyses changes to the battery status over time. When we examine a new battery, the AI compares the data with that of other batteries, accurately determining the state of health.
In the next step, the software calculates the battery’s current value and determines if it is suitable for reuse. After that, it can be made available on our digital marketplace, where we offer lithium-ion batteries, nickel manganese cobalt batteries and lithium-iron-phosphate batteries. For batteries that we can monitor through the BMS while they are still in use in the vehicle, we can forecast the point at which they need to be exchanged.
Our extensive data collection and the vast number of battery analysis results in our system allow for more accurate recycling planning for batteries that are not suited for a second-life application. In that case, the battery is offered to a qualified recycling company. This is how we create a digital circular battery economy and optimize life cycle management. Within this circular economy, Circunomics operates the digital marketplace, offers analyses, organizes and monitors sales and payments, and recommends professional logistics partners.
When we started out back in 2019, second-life batteries were not receiving much attention. This has changed a lot, and based on our market growth, we can give you several examples: The battery capacity available via our marketplace has grown to more than five gigawatt hours – enough to supply ees Europe with electricity for a whole week.
We are also growing internationally. Since January 2025, we have a US team offering our battery solutions. By the end of 2026, we also want to be present in the – very complex – Asian market.
Our business model has the great advantage of being fully digital, which means that both our analyses and our marketplace are globally accessible. This brings us closer to our goal of bringing used or surplus batteries to sustainable use and keeping them in the circle. From the passenger car sector alone, between five and six million end-of-life batteries are expected to flood the market in 2030.
Circunomics is an exhibitor at ees Innovation Hub in Hall B0, booth B0.155.
ees Innovation Hub is a special exhibition area of ees Europe, Europe's largest and most international exhibition for batteries and energy storage systems, highlighting innovative companies and research institutes in the storage industry.