Second-Life Applications For Used Lithium-Ion Batteries

Article Summary

1. Second-life lithium-ion batteries are emerging as a practical way to extend the value of EV battery packs while supporting renewable energy infrastructure.
2. Many EV batteries retain sufficient capacity after vehicle use to serve in stationary energy storage systems, particularly for solar and grid-support applications.
3. Repurposing used batteries helps reduce reliance on newly manufactured cells and supports sustainability goals.
4. Second-life use introduces elevated safety risks due to years of cycling, vibration, temperature exposure, and potential latent defects.
5. Remote, stationary grid storage is widely considered the safest and most appropriate second-life application, minimizing human exposure and failure consequences.
6. UN 38.3 testing establishes a baseline safety certification for lithium-ion battery designs, but it does not account for degradation from years of use.
7. Using second-life batteries in vehicles or people-dense environments carries significantly higher risk, especially when battery history and internal condition are unknown.
8. Higher state-of-charge levels common in used batteries increase the severity of potential thermal events during transport and storage.
9. Standard fiberboard packaging is inadequate for second-life batteries; thermal containment solutions are critical to prevent escalation during failures.
10. Regulatory bodies and industry groups are actively debating whether additional or modified testing should be required for second-life batteries.
11. Battery manufacturers express concern when products are repurposed outside applications they originally designed or certified.
12. The industry faces an ongoing balance between sustainability benefits and acceptable safety risk.
13. A responsible second-life strategy prioritizes appropriate applications, stricter handling and storage controls, and engineered containment solutions.
14. With evolving regulations and proper planning, second-life batteries can play a meaningful role in a safer, more resilient energy ecosystem.

Giving Lithium-Ion Batteries a Second Life

At Americase, we work at the intersection of hazmat safety, energy innovation, and industrial logistics, and few topics reflect this space as clearly as the growing use of second-life lithium-ion batteries. As electric vehicles reach the end of their operational life, the battery packs inside them often retain enough capacity to serve in new roles. Instead of sending these batteries directly to recycling, more companies are repurposing them into lithium battery energy storage systems that support renewable power infrastructure. 

These systems can be particularly valuable in solar installations, where energy generated during the day needs to be stored for nighttime use. By aggregating large numbers of used EV packs into freight-container storage units, operators can create reliable, cost-effective storage systems without relying entirely on newly manufactured batteries.

Second-life use also introduces important safety considerations. After years of cycling, vibration, and road wear, used lithium-ion packs carry a higher inherent risk of internal defects or thermal events. That complexity makes it essential to understand when second-life use is appropriate and how to transport, store, and package these batteries safely. Our work in UN-compliant containment solutions helps customers manage these risks with confidence. As battery volumes rise, the decisions manufacturers, integrators, and logistics leaders make today will help shape the future of energy storage safety and sustainability.

Why Second-Life EV Batteries Are Best Used in Remote Grid Storage Systems

One of the most practical and widely accepted use for second-life lithium-ion batteries is stationary grid storage in remote areas. Our view is that this application balances sustainability and safety because it uses the remaining capacity of used EV packs in environments where the consequences of a failure are minimal. This perspective aligns with the National Renewable Energy Laboratory, which continues to publish research on the promise of repurposed EV batteries in grid-support applications.

A foundational safety layer comes from UN 38.3, which subjects all new lithium-ion battery designs to eight transport safety tests. These tests evaluate vibration, altitude, shock, external short circuit, and overcharge performance. Once a battery design passes, the certification remains valid for the battery’s entire lifespan. The full criteria are outlined in the UN Manual of Tests and Criteria.

A real-world scenario shows how these batteries transition from vehicle use to grid assets. A solar farm operator decommissions a fleet of EVs and consolidates their used battery packs into ISO-sized outdoor containers placed along the perimeter of the facility. During the day, solar panels generate electricity that charges the batteries; at night, the stored energy feeds back into the grid. Stationary energy storage remains one of the most rational directions for second-life batteries because it creates a predictable environment with limited human exposure while helping companies advance sustainability goals.

The High-Risk Reality of Using Second-Life Batteries in Vehicles and People-Dense Facilities

While remote grid storage is a safe and practical second-life use, repurposing used lithium-ion batteries for applications where people are nearby presents potential risks because these batteries have already endured years of cycling and physical stress.

Most EV batteries remain in service for five to ten years, during which they experience vibration, temperature swings, and occasional mechanical impacts. Even when a used battery appears intact, its internal condition can differ dramatically from a new pack. The EPA warns that used lithium-ion batteries can contain latent defects that don’t appear visually but still pose a fire hazard during reuse or handling.

A clear example highlights the potential risk. An independent EV repair shop replaces a failed module in a customer’s battery pack with a used module harvested from a salvaged EV. That donor module may have been in a vehicle that experienced a minor collision or repeated overheating. Even if both modules appear functional, the mismatch in wear and chemistry can introduce imbalances that increase the chance of thermal runaway once installed in a working EV. When this happens in a garage, parking structure, or warehouse, the consequences are far more severe than in a remote container yard. Battery manufacturers also express concern about unauthorized second-life use. Many hesitate to support applications they didn’t design or certify.

Why Second-Life Batteries Should Have Stricter Packaging, Handling, and Warehousing Controls

Even when they’re still functional, second-life batteries must be handled and stored with more caution than new units. Companies should treat these batteries as higher-risk cargo because of their age, cycling history, and unknown internal conditions.

A key fact is that second-life batteries often arrive at higher states of charge, unlike new units that are shipped at reduced charge levels for safety. Higher stored energy increases the severity of potential thermal events during transport or storage. DOE and FSRI research confirms that high-SOC lithium-ion batteries are more likely to propagate fire if damaged.

Storing used battery packs in standard fiberboard cartons is risky as even a minor failure could ignite packaging materials and escalate rapidly; it is safer to use containers that offer thermal containment capabilities. 

UN 38.3 Testing, Retesting Debates, and the Safety–Sustainability Tug-of-War

Testing and certification form the final piece of the second-life challenge. Our position is that while current rules don’t require retesting second-life batteries, the industry should anticipate evolving expectations and consider whether additional verification is appropriate.

UN 38.3 remains the global safety baseline. It requires eight tests evaluating vibration, altitude, short circuit protection, and more. Once passed, a design is approved for transport for the remainder of its life. However, given that the battery has been used and gone through many charge cycles, the regulatory bodies might move towards implementing a “lighter” version of the test to certify second-life batteries. The International Energy Agency notes that as second-life markets expand, regulators worldwide are evaluating whether new testing protocols are needed for repurposed batteries in the section of the article titled, “Battery recycling technology and industry players are already getting ready for the 2030s.”

Battery manufacturers are also part of this conversation. Some express discomfort when their products are placed in second-life applications they didn’t validate. This discussion reflects a larger question for the industry: how much safety risk are we willing to accept to achieve sustainability gains?

Building a Responsible Second-Life Battery Strategy That Protects People and Power Infrastructure

Second-life lithium-ion batteries offer a meaningful opportunity to extend the usefulness of a resource-intensive product while supporting sustainability goals. Yet repurposing batteries that have already endured years of cycling and road exposure comes with inherent safety challenges. Many believe the most appropriate second-life applications are stationary energy storage deployments in remote areas, where elevated risk can be effectively managed.

Higher-risk uses in vehicles or people-dense facilities don’t offer the same safety profile. As more batteries reach the end of their first life, companies must evaluate not only performance but also history and condition.. Americase’s custom-engineered containment solutions and advanced testing capabilities through our sister company Fulcrum Testing, provide the tools needed to help manage risk.

As UN 38.3 and other regulatory frameworks evolve, the industry will continue balancing safety with sustainability. With thoughtful planning and the right partners, second-life batteries can contribute to a safer, more resilient energy future.

Do you have questions about your company’s compliance? Schedule a quick call with our expert today.