The math for a used electric car battery, once its driving range has faded, is not complicated. It still holds perhaps 70% of its original capacity, a bank of lithium-ion cells engineered for automotive-grade safety and performance. The landfill is a spectacularly bad answer. The better one, if you can manage the logistics, testing, and power electronics, is to give it a second job smoothing out the grid. In Stockholm, Rebaba is building that answer into shipping containers, and selling them to businesses that would rather not pay peak electricity prices.
Founded in 2023, Rebaba is a classic example of Nordic industrial pragmatism meeting the energy transition. The proposition is straightforward: source battery packs from end-of-life EVs, rigorously test and reconfigure them into modular storage units, and sell these systems to commercial and industrial customers. The tagline is "circular battery storage," a phrase that does the heavy lifting on both the sustainability pitch and the unit economics. If the cells are cheaper than new ones,and they are,you can offer storage at a lower cost per kilowatt-hour, while also telling a greener story. The company’s first visible commercial move is a partnership with Swedish energy wholesaler KP Energy, which is now offering Rebaba’s containerized systems [nordiskaprojekt.se, 2026].
A wedge of cost and carbon
For a commercial operator, the appeal of second-life storage hinges on two numbers: the capital cost per kilowatt-hour of capacity, and the avoided cost of grid electricity during peak times. New grid-scale lithium-ion batteries have seen prices fall, but they still represent a significant upfront investment. A used EV battery pack, acquired at a fraction of its first-life cost, changes the starting point. Rebaba’s bet is that by owning the technical process of assessment, repackaging, and system integration, they can deliver reliable storage at a price point that makes sense for a mid-sized business or a municipal energy project.
The sustainability angle is not just marketing. Giving batteries a second life postpones recycling, which itself is energy-intensive. It also reduces demand for new mining and manufacturing. For customers like KP Energy, which is positioning itself as a provider of circular solutions, this is a tangible product to sell [dagenslogistik.se, Unknown]. For others, it might simply be a cheaper way to add on-site storage for solar power or to participate in grid-balancing services.
The team from Northvolt and the ecosystem push
The founders, Paula Runsten and Felix Kruse, bring relevant industrial pedigree. Runsten, the CEO, has a background at Tesla and Northvolt, the Swedish battery giant [di.se, Unknown]. Kruse, the CTO and COO, also has experience from Northvolt and an engineering education from Lund University [linkedin.com, 2026]. This isn’t a team coming from fintech; their resumes point directly at the battery supply chain they aim to tap into.
Their early progress appears less about splashy venture rounds and more about stitching together the right ecosystem support. The company announced a pre-seed round of 5.5 million SEK (roughly $501,000) [rebaba.se, Unknown]. More notably, Rebaba is part of a Vinnova-funded project called 'Industrial Scaling of a Circular Battery Value Chain,' which includes heavyweight partners like Stena Recycling, OKQ8 Group, Smartports, and the research institute RISE [miningmetalnews.com, 2025]. In October 2025, they signed a strategic collaboration with Smartports to scale circular battery-powered solar carports across Europe [news.cision.com, 2025]. These are the kinds of alliances that matter for a hardware-heavy, logistics-complex business,they provide channels, feedstock, and credibility.
| Partner | Role | Type |
|---|---|---|
| KP Energy | First wholesaler in Sweden to launch Rebaba's systems | Commercial distributor [nordiskaprojekt.se, 2026] |
| Smartports | Strategic collaborator for solar carports across Europe | Development & deployment partner [news.cision.com, 2025] |
| Stena Recycling | Partner in Vinnova industrial scaling project | Recycling & feedstock logistics [miningmetalnews.com, 2025] |
| OKQ8 Group | Partner in Vinnova industrial scaling project | Energy & retail network [miningmetalnews.com, 2025] |
The known unknowns of second-life supply
The model is elegant on paper, but its scalability faces real questions. The entire business depends on a predictable, high-quality supply of used EV batteries. Today, that stream is still nascent. While millions of EVs are on the road, the first major wave of them hasn’t yet reached end-of-life in large numbers. The batteries that are available can vary wildly in chemistry, condition, and history, making the testing and standardization process critical,and costly.
- Supply chain fragility. Rebaba’s feedstock depends on the decisions of carmakers, recyclers, and regulations. If automakers pursue their own second-life programs or if recycling becomes more economically attractive, the cost of cores could rise.
- Performance variance. A storage system is only as good as its weakest cell. Managing degradation across a heterogeneous pack of used cells requires sophisticated battery management software, a non-trivial engineering challenge.
- Market education. Convincing a factory manager to trust their energy resilience to used batteries, rather than shiny new ones, requires a clear demonstration of safety and reliability. Standards and certifications will be key.
Rebaba’s participation in the Vinnova project with Stena Recycling is a direct attempt to de-risk the supply chain question. By working with one of Europe’s largest recycling firms, they are building a relationship right at the source of the battery waste stream.
The path from first container to first fleet
For now, Rebaba is in the early deployment phase. The partnership with KP Energy is a start, providing a sales channel. The collaboration with Smartports points to a specific application: using the containers to store solar power at carports, creating integrated renewable energy hubs. The company has also delivered a grid-connected system built with El och Marinteknik [cbinsights.com, Unknown]. The next twelve months will likely be about proving repeatability,moving from one-off projects to a steady flow of deployments.
The financial runway from the pre-seed round is limited for a hardware venture. A logical next step would be a seed round to fund more containers, build inventory, and grow the small team, which is reported at six employees [pitchbook.com, 2026]. The investor group from the pre-seed includes Rockstart, RadCap, and several angels [rebaba.se, Unknown], a mix that suggests backers who understand deep tech and circular economy models.
A back-of-the-envelope sense of the opportunity: If a typical second-life system costs 40% less upfront than a new one, that’s a compelling discount for a commercial customer. But the real savings come over time, by shifting energy consumption away from peak tariffs. For a medium-sized business with a steady load, the system might pay for itself in a few years. The carbon saving is a bonus, one that is increasingly quantified and valued.
Rebaba’s ultimate competition isn’t just other second-life startups like BatteryLoop or Evyon. It’s the incumbent logic of buying new. To win, they need to prove that ‘circular’ is more than a label,that it’s a reliable, cost-effective way to keep the lights on.
Sources
- [rebaba.se, Unknown] Rebaba secures 5.5 million SEK pre-seed round | https://rebaba.se/news/rebaba-secures-5.5-million-sek-in-pre-seed
- [nordiskaprojekt.se, 2026] KP Energy första grossist i Sverige med Rebabas cirkulära batterilösningar | https://www.nordiskaprojekt.se/2026/03/19/kp-energy-forsta-grossist-i-sverige-med-rebabas-cirkulara-batterilosningar/
- [dagenslogistik.se, Unknown] Cirkulära lösningar ska stärka energigrossisten | https://dagenslogistik.se/cirkulara-losningar-ska-starka-energigrossisten/
- [di.se, Unknown] Paula Runsten has background from Tesla and Northvolt | https://di.se
- [linkedin.com, 2026] Felix Kruse - Rebaba | LinkedIn | https://www.linkedin.com/in/felixkruse1/
- [miningmetalnews.com, 2025] Vinnova co-funded project 'Industrial Scaling of a Circular Battery Value Chain' | https://miningmetalnews.com
- [news.cision.com, 2025] Strategic collaboration with Smartports signed October 8, 2025 | https://news.cision.com
- [cbinsights.com, Unknown] Delivered grid-connected energy storage system with El och Marinteknik | https://cbinsights.com
- [pitchbook.com, 2026] Rebaba 2026 Company Profile | https://pitchbook.com/profiles/company/572117-68