Convenience-Store Battery Swapping as Urban Energy Access Infrastructure:A Physical-API Framework for Standardized Battery-as-a-Service in Human Mobility and Future Physical-AI Systems

This paper reframes battery swapping from a vehicle-refueling problem into an urban energy-access problem. Conventional battery-swapping research usually focuses on charging speed, station placement, battery inventory, or fleet optimization. This paper argues that for mobile workers, outdoor vendors, assistive-mobility users, camping users, and future embodied machines, the deeper constraint is whether usable electricity is available at the required time, place, interface, cost, and safety condition. The paper names this burden electric access friction: the pre-use cost a user faces before stored electricity becomes practically usable. The central contribution is a convenience-store Battery Swapping Station framework organized around a certified physical API. The physical API is not a software interface, but a hardware certification contract that translates a standardized portable battery into device-class-specific voltage, current, connector, mounting, communication, and safety requirements. The paper uses a 1.2 kWh-class reference battery as an analytical boundary object, not as a universal battery or final commercial specification. A device or user segment enters the framework only if it fits the certified power, handling, safety, and adapter envelope. The paper proposes a 5+1 demand model: five human-market candidates plus a future physical-AI extension. The human markets include delivery riders, camping and outdoor users, vendors, paid designated drivers, and elderly or assistive-mobility users. The physical-AI layer is treated only as a future strategic extension, not as part of the Phase 1 empirical unit or near-term profitability claim. Demand is admitted through an explicit rule: the segment must use electricity away from fixed outlets, suffer material loss when depleted, fit the reference pack and adapter envelope, and intersect with convenience-store access patterns. A 2025 source-calibrated economic case evaluates a twenty-store illustrative network with 480 feasible swaps per day. Break-even requires roughly 400 swaps per day, or about 83% utilization. The main result is not that convenience-store BSS is already profitable, but that the binding constraint is demand aggregation rather than cabinet capacity. Under conservative omitted-cost overlays, the base price is insufficient, so practical viability depends on measured adoption, premium pricing, business-to-business commitments, or cost reduction. The manuscript is a design-science and pilot-protocol paper, not a field-validation report. It specifies a staged pathway from Phase 0 desk validation and Phase 0.5 user survey to a narrow Phase 1 pilot of ten stores, one adapter class, one anchor segment, and thirty days. Success is judged by a conjunctive decision rule: traceability, adoption, utilization, economics, safety, store burden, and stakeholder alignment must pass together. Failure in one branch narrows the applicable segment, adapter class, price point, or host configuration rather than being offset by success elsewhere. The paper therefore advances a practical design rule: define the access friction, bound the energy object, certify the interface, admit only valid demand, measure utilization and cost, and gate safety before scaling. Before scaling, test access. Keywords: battery swapping, Battery-as-a-Service, urban energy access, electric access friction, physical API, convenience-store infrastructure, portable energy, micromobility, pilot protocol, traceability, certified adapter, demand aggregation, design science, safety gating, physical AI.