{"id":18222,"date":"2025-11-29T22:52:32","date_gmt":"2025-11-29T21:52:32","guid":{"rendered":"https:\/\/www.tcs-engineering.de\/second-life-or-recycling-second-life-reuse-of-traction-batteries-technology-safety-and-system-design-for-practical-applications\/"},"modified":"2025-11-29T22:53:42","modified_gmt":"2025-11-29T21:53:42","slug":"second-life-or-recycling-second-life-reuse-of-traction-batteries-technology-safety-and-system-design-for-practical-applications","status":"publish","type":"post","link":"https:\/\/www.tcs-engineering.de\/en\/second-life-or-recycling-second-life-reuse-of-traction-batteries-technology-safety-and-system-design-for-practical-applications\/","title":{"rendered":"Second life or recycling? Second-life & reuse of traction batteries: Technology, safety and system design for practical applications"},"content":{"rendered":"

How traction batteries convince after the car in stationary and mobile applications – and what engineers and decision-makers need to pay attention to.<\/strong><\/h2>\n

<\/strong><\/p>\n

Why Second Life makes technical sense<\/strong><\/h3>\n

Traction batteries are the most valuable and complex part of electric drives – and they age. At the end of automotive use, their condition determines the next step: reuse in the vehicle, reassignment to less demanding applications (“second life”) or dismantling\/recycling. This path decision is not a gut feeling, but follows measurable parameters such as capacity, internal resistance and freedom from defects. <\/p>\n

The rededication to stationary or semi-stationary storage (e.g. PV intermediate storage, construction site or emergency lighting supply) as well as mobile uses with moderate dynamics (e.g. industrial trucks) is particularly attractive. These categories – stationary, semi-stationary, mobile – structure the requirements and help with the selection of suitable batteries. <\/p>\n

From the cell to the system: what really counts<\/strong><\/h3>\n

Technically speaking, a battery is more than the sum of its cells. For safe operation, cell voltage, temperature and battery current must be continuously monitored; typical Li-ion cells operate around 3.6 V nominal voltage, with limit values that can lead to degradation and even safety risks if exceeded or undercut. A modern system includes modules with cell monitoring and balancing (CSC\/ASIC), a control unit for SOC\/SOH calculation and power management, (ev) high voltage contactors and current measurement – often redundant. <\/p>\n

Why is this so important? Because the subsequent second-life load profiles (e.g. many flat cycles in grid operation vs. several hours of cycling in home storage) directly determine life expectancy, efficiency and safety – and therefore whether a used traction battery is suitable for the target profile at all. <\/p>\n

Measuring instead of guessing: Determine SOC, DOD, SOH accurately<\/strong><\/h3>\n

Solid condition diagnostics are the ticket to any reuse project. The state of charge SOC is the ratio of the currently charged Ah to the available capacity; the depth of discharge DOD is calculated as 100 % SOC. The state of health SOH is defined as the ratio of the current full capacity to the nominal capacity; below a typical threshold value of around 80 %, this is referred to as the end of the original service life (depending on the application). <\/p>\n

From an engineering perspective, this means that no second-life release is possible without reliable SOH, SOC and internal resistance diagnostics<\/strong> – ideally with reproducible test procedures that map the target profile (currents, temperatures, cycle windows).<\/p>\n

Understanding ageing – planning second life realistically<\/strong><\/h3>\n

Ageing is not linear. It is influenced by temperature, current rates and cycle windows; the capacity curve typically flattens out slightly at first before falling more sharply. In second-life scenarios, application ranges above ~50-80 % residual capacity are often used (depending on the specific application) in order to have sufficient reserve for degradation in second use. <\/p>\n

Pragmatic examples show that this works: From PV home storage systems to grid-supporting large-scale storage systems and semi-stationary solutions, there are real pilot and practical projects that successfully operate second-life batteries.<\/p>\n

EOL-IS as a process concept: from expansion to commissioning<\/strong><\/h3>\n

Reuse is a process, not a single step. An end-to-end process – from removal, diagnostics, disassembly\/reassembly to integration, testing and commissioning – minimizes risks and costs. The systematic approach behind this: orderly evaluation, data-based assignment to the appropriate application and documented commissioning in the target system. <\/p>\n

Engineer takeaway:<\/strong> Define the target use case first (e.g. PV shift vs. grid support). Then set limits for SOH, internal resistance, temperature window, C-rate and approved DOD. Only when the battery has passed these criteria will the conversion be economically viable – and remain safe. <\/p>\n

Requirement profiles: stationary, semi-stationary, mobile – short & crisp<\/strong><\/h3>\n