BSDO

Battery Swap Domain Ontology

Battery swapping is more complicated than it looks.

Swapping a battery takes about a minute. Describing what happened — who owns the pack, who is holding it, whether it will come back — takes a vocabulary that charging-oriented standards never needed.

What everyone sees

One minute, four steps

  1. 01

    Motorcycle

    arrives with a depleted pack

  2. 02

    Swap station

    opens a door

  3. 03

    Old pack out

    goes into the cabinet

  4. 04

    New pack in

    rider leaves in a minute

Nothing about that is hard. The difficulty starts the moment two operators try to describe it in the same terms — or the moment anyone asks a question the picture does not answer.

What the picture leaves out

Four questions it cannot answer

  • Whose battery is it?

    The rider paid for the vehicle but often not for the pack. Ownership and physical custody move independently, so BSDO records them as two separate relations rather than one.

    ownedByheldBy

  • Was that a swap, a loan, or a deposit?

    Three transactions look identical at the cabinet door. They differ in whether the same pack comes back, and whether ownership moved with it.

    Custody-Preserving Event
  • Is a pack an object, or is it energy?

    Charging transfers energy into a carrier that stays put. Swapping transfers the carrier itself. Treating the second as a variant of the first loses the object.

    Object Transfer Event
  • Does the same voltage mean the same pack?

    No. Two packs can agree on nominal voltage, agree on practical capacity, and still be unusable in each other's stations.

    Lithium-Ion-Only Device

A case from the data

Two packs agree on voltage. They still cannot be exchanged.

 SWAP battery, 64 V classSWAPVolta SGB battery, 64 V classVolta
Voltage class60 V, 64 V64 Vagrees
Capacity1.3 kWh21 Ah
Cell chemistryLithium-Ion (generic)LiFePO4conflict

Both packs are rated at 64 V. Their practical capacities are close enough that a rider would not notice. Even the units disagree — one operator publishes kilowatt-hours, the other ampere-hours — so the figures cannot be compared without knowing which quantity each one names.

The chemistries differ, and each operator’s cabinets accept only their own. An ontology that records this does more than store the fact: asked to accept the wrong pack, it returns a contradiction rather than an empty answer.