Implementing the EU Battery Passport for Small Manufacturers: A Multi-Tenant Digital Product Passport Architecture (AmpPass)

Regulation (EU) 2023/1542 requires an electronic battery passport, reachable through a QR code, for every light means of transport (LMT) battery, industrial battery above 2 kWh, and electric-vehicle battery placed on the European Union market from 18 February 2027. Small and medium-sized battery pack manufacturers must meet this mandate without the enterprise tooling of large cell producers. This paper presents the Digital Product Passport (DPP) architecture of AmpPass (https://amppass.eu and https://amppass.dk), a multi-tenant software platform derived from the production workflow of a Danish battery-pack manufacturer (Batteri Energi ApS). We detail a deterministic six-source field-provenance model (model, model_spec, derived, production, company, and unit), a public versus legitimate-interest access split mapped to Annex XIII, per-company database isolation using least-privilege runtime credentials, subscription-independent public QR resolution, and a strict data-integrity rule where unknown values remain explicitly unknown rather than estimated. We also provide a transparent capability matrix distinguishing implemented features from partial or unconfigured components.