“SOH What ?” The Role of State of Health (SOH) in the Construction of the Used Electric Vehicle Market: Social Representations, User Practices, and Market Dynamics.

Keywords:

Abstract:

In the context of the transition towards a more circular automotive economy, battery durability is a critical lever for reducing strategic dependencies and fostering the "second life" market. This paper examines how users and market actors engage with battery ageing. It seeks to understand how the State of Health (SOH) concept and battery diagnostic tools (SOH-DT) emerge as instruments for reassurance or market valuation, while analysing the pivotal role of manufacturers in controlling this technical information. This research aligns with the colloquium's focus on shifting from linear to circular business models and the quest for economic sovereignty.

The study is based on field research combining qualitative and quantitative approaches. First, an analysis of social representations and user knowledge regarding the physico-chemical processes of battery ageing was conducted through sociological semi-structured interviews (n=20). These data explore the used-EV buying process, as well as usage and charging practices—specifically the analysis of institutionalised habits such as 20-80% charging cycles and the use of rapid chargers—regarding battery life-cycle optimisation. Second, a quantitative approach investigates used EV market dynamics through data extraction from the French Leboncoin platform, measuring the growth in frequency of the term "SOH" in sales advertisements and comparing private and professional car sellers. Finally, we present an analysis of the role of manufacturer warranties as a primary trust-building mechanism and discuss how third-party SOH diagnostic tools may play a role in a post-warranty market.

The results highlight a significant gap between awareness of the issue and technical mastery:

Fragmented knowledge: While users identify the challenge of ageing, technical concepts such as SOH or battery diagnostics remain poorly understood by most respondents, with the exception of a few technophiles.

Institutionalised habits: Nevertheless, users adopt specific battery preservation practices, such as limiting the frequency of rapid charging and maintaining the State of Charge (SoC) between 20% and 80%, a practice frequently encouraged by professional sellers.

Emergence of SOH in the second-hand EV market: A significant upward trend in the use of the term "SOH" is observable in used electric vehicle (UEV) advertisements, primarily driven by personal sellers who use it as a key selling point and a tool for differentiation from profesionnal dealers (who can offer warranties, loans, etc.).

Informational monopoly: Car manufacturers maintain a "monopoly of legitimacy" over SOH data, remaining the preferred actors for conducting diagnostics despite providing what is often perceived as limited information. Third-party tools remain poorly known by many interviewees.

The centrality of warranty: Current battery warranty schemes act as a "safety net," which presently limits the perceived necessity for independent diagnostics for relatively new vehicles.

Theoretically, this research contributes to industrial and academic debates on new electrification business models and the structural obstacles to the circular economy. Practically, the study suggests that structuring a robust used market depends on democratising access to battery health data. It argues that public policies—such as the European Digital Product Passport (Rizos V., Urban P., 2024)—must address the manufacturers' monopoly to ensure market transparency. Consumer education and the standardisation of diagnostics are essential levers for extending vehicle lifespans and ensuring the long-term viability of recycling and reuse sectors.

References:

Akerlof, George, A., 1970, « The Market for “Lemons”: Quality Uncertainty and the Market Mechanism », The Quarterly Journal of Economics, 84, 3, p. 488‑500. https://doi.org/10.2307/1879431

Borg, Kevin. « Les sens perdus du garagiste. Comment le savoir-faire a été disqualifié dans l’univers automobile américain ». Revue d’histoire moderne & contemporaine 593, nᵒ 3 (2012): 19‑47. https://doi.org/10.3917/rhmc.593.0019.

Callon, Michel, Cécile Méadel, et Vololona Rabeharisoa. « L’économie des qualités ». Politix. Revue des sciences sociales du politique 13, nᵒ 52 (2000): 211‑39. https://doi.org/10.3406/polix.2000.1126.

Denis, Jérôme, et David Pontille. Le soin des choses. Politiques de la maintenance. La Découverte, 2022. https://doi.org/10.3917/dec.denis.2022.01.

Dutertre, Emmanuelle, et Bernard Jullien. « Le développement contrarié de la grande distribution dans l’après-vente automobile ». Gestion. Revue Française de Socio-Économie 16, nᵒ 1 (2016): 81‑98. https://doi.org/10.3917/rfse.016.0081.

Karpik, Lucien. L’économie de la qualité. Persée - Portail des revues scientifiques en SHS, 1989. https://doi.org/10.2307/3321761.

Labeye E., Hugot M., Brusque C., Regan M.A., 2016, « The electric vehicle: A new driving experience involving specific skills and rules », Transportation Research Part F: Traffic Psychology and Behaviour, 37, p. 27‑40. https://doi.org/10.1016/j.trf.2015.11.008

Pichelmann S., Franke T., Krems J.F., 2013, « The Timeframe of Adaptation to Electric Vehicle Range » Kurosu M. (dir.), Human-Computer Interaction. Applications and Services, p. 612‑620. https://doi.org/10.1007/978-3-642-39262-7_69

Rizos V., Urban P., 2024, « Implementing the EU digital battery passport », CEPS IN-DEPTH ANALYSIS, Brussels, CEPS.