1. Introduction & Motivation
The “TraFuSMS – Training for Future Skills in Sustainable Mobility Solutions” project, led by the Electric Vehicle Institute of Bochum University of Applied Sciences, the Dortmund Chamber of Crafts, and the Motor Vehicle Trade Guild Bochum, aims to develop a modular training concept for the energy and mobility transition in the Ruhr region. Supported by Bochum Economic Development and the Chamber of Commerce and Industry, the project focuses on maintaining traction batteries, hydrogen systems, and sustainable energy solutions. As EVs age beyond warranty periods, independent workshops increasingly handle maintenance and battery diagnostics. To equip automotive professionals, the project develops training programs for State-of-Health (SOH) estimation of traction batteries. This study examines workshop-suitable SOH assessment methods, differentiating between capacity (SOH(C)), affecting user experience, and internal resistance (SOH(R)), a service parameter influenced by external factors.

2. SOH Estimation Methods

2.1 DC Methods: Continuous DC methods apply a steady current to analyze capacity and voltage characteristics. Charge-Discharge Profiling offers accurate SOH(C) estimation but requires long testing times. Pulsed DC methods use short current pulses, analyzing voltage response. The DC Internal Resistance Test measures voltage drop to estimate SOH(R), offering fast, simple testing. Pulsed Current Charging refines SOH(C) and SOH(R) estimations by allowing relaxation between pulses, improving accuracy over single-pulse tests.

2.2 AC Methods: AC methods apply alternating current at different frequencies to analyze impedance response. The AC Internal Resistance (ACIR) Test measures impedance, providing SOH(R) estimations. While fast and repeatable, it requires reference data and specialized equipment and is sensitive to contactor conditions and temperature variations.

3. Conclusion
Workshop SOH estimation must balance speed, simplicity, and accuracy while minimizing equipment costs and safety risks. DC methods provide high SOH(C) accuracy but require longer test durations. AC methods, such as ACIR, enable fast and manufacturer-independent SOH(R) estimation, ideal for routine diagnostics. Pulsed DC and ACIR methods offer the best balance of efficiency and accuracy, though they may not differentiate battery degradation from faulty connections. A layered diagnostic approach enhances reliability and cost-effective battery servicing, preparing workshops for the expanding EV market.