> ## Documentation Index > Fetch the complete documentation index at: https://docs.kapa.energy/llms.txt > Use this file to discover all available pages before exploring further. # Get battery information > Static characteristics of the battery, standardised across manufacturers. ## OpenAPI ````yaml /openapi.yaml get /bat/v1/{id}/info openapi: 3.1.0 info: title: Kapa Energy Battery API version: 1.0.0-draft.1 summary: One API to control and monitor residential batteries across manufacturers. description: > The Kapa Energy Battery API gives HEMS and VPP operators a single interface to send commands to residential batteries and read their telemetry, whatever the manufacturer. Kapa translates each request into the manufacturer's own cloud API. ## Conventions ### Time - Timestamps are RFC 3339, in UTC, with a `Z` suffix: `2026-11-12T18:00:00Z`. - Durations are ISO 8601: `PT15M`. - Time windows are half-open, `[start, end)`: `start` is included, `end` is excluded. ### Power Power is in watts (W), as integers. - **Positive (+)**: the battery is discharging, or the site is exporting to the grid. - **Negative (−)**: the battery is charging, or the site is importing from the grid. Nominal ratings such as `nominal_charge_power_w` are magnitudes and are always positive. ### Energy Energy is in watt-hours (Wh), as integers. Battery levels are expressed as stored energy in Wh rather than state of charge in %, because the meaning of SoC differs between manufacturers. Stored energy is measured against the usable capacity: it ranges from 0 to `usable_capacity_wh`. ### Telemetry - Each data point carries two times: `measured_at`, when the device took the measurement, and `received_at`, when Kapa retrieved it from the manufacturer's cloud. - Data points are never interpolated or resampled. Each point is an actual measurement reported by the manufacturer. Units, signs and field names are standardised across manufacturers; a field the manufacturer does not report is `null`. ## Commands - Commands are asynchronous. Command endpoints return `202 Accepted` with a command whose `status` then evolves. Follow it with `GET /bat/v1/{id}/commands` or the `command.status_changed` webhook. - A `start` in the past is treated as the time Kapa accepts the command. - **Overlaps:** when a new command overlaps existing commands on the same battery, the newest command takes precedence over the overlapping period. Older commands stay in effect outside it. A command whose whole window is covered by newer commands becomes `superseded`. - Outside any command window, the battery follows its **default behaviour**: the mode its owner configured in the manufacturer's app. ## Idempotency Command and batch endpoints accept an optional `Idempotency-Key` header. Kapa stores the key with the response for 24 hours. A retry with the same key and the same body returns the original response without sending anything again. ## Errors Errors use RFC 9457 Problem Details (`application/problem+json`). The `code` field is stable and meant for programs; `title` and `detail` are meant for humans. | `code` | HTTP | Meaning | |---|---|---| | `invalid_parameters` | 400 | A parameter is missing, malformed or inconsistent (e.g. `min_wh` greater than `max_wh`). | | `invalid_time_window` | 400 | `start` is not before `end`, or `end` is in the past. | | `overlapping_operations` | 400 | Two operations of a batch target the same battery over overlapping windows. | | `unauthorized` | 401 | The access token is missing, invalid or expired. | | `battery_not_found` | 404 | No battery with this id is accessible to the client. | | `idempotency_key_in_use` | 409 | A request with the same `Idempotency-Key` is still being processed. | | `action_not_supported` | 422 | The battery cannot apply this command or parameter (e.g. `allow_import: false`). | | `energy_out_of_range` | 422 | An energy level exceeds the battery's usable capacity. | | `idempotency_key_reused` | 422 | The `Idempotency-Key` was already used with a different request body. | ## Webhooks Kapa pushes telemetry and command status changes to an HTTPS endpoint. Delivery is at least once and not ordered: deduplicate with `event_id`, and order data with `measured_at` or `updated_at`. Webhook registration is not covered by this version of the API. servers: - url: https://api.kapa.energy description: Production security: - oauth2: [] tags: - name: Authentication description: Obtain an OAuth 2.0 access token. - name: Batteries description: Static information about a battery. - name: Commands description: Control a single battery and follow the status of its commands. - name: Batches description: Send commands to many batteries in one request. - name: Telemetry description: Read measurements, standardised across manufacturers. paths: /bat/v1/{id}/info: parameters: - $ref: '#/components/parameters/BatteryId' get: tags: - Batteries summary: Get battery information description: >- Static characteristics of the battery, standardised across manufacturers. operationId: getBatteryInfo responses: '200': description: Battery information. content: application/json: schema: $ref: '#/components/schemas/BatteryInfo' example: id: bat_1 manufacturer: Acme Storage model: Home 13 firmware_version: 4.2.1 nominal_capacity_wh: 14000 usable_capacity_wh: 13000 nominal_charge_power_w: 5000 nominal_discharge_power_w: 5000 power_measurement_side: ac '401': $ref: '#/components/responses/Unauthorized' '404': $ref: '#/components/responses/NotFound' components: parameters: BatteryId: name: id in: path required: true description: Battery identifier. schema: type: string example: bat_1 schemas: BatteryInfo: type: object required: - id - manufacturer - model - firmware_version - nominal_capacity_wh - usable_capacity_wh - nominal_charge_power_w - nominal_discharge_power_w - power_measurement_side properties: id: type: string description: Battery identifier. manufacturer: type: string description: Manufacturer name. model: type: string description: Model name, as reported by the manufacturer. firmware_version: type: - string - 'null' description: Firmware version, as reported by the manufacturer. Null if unknown. nominal_capacity_wh: type: integer minimum: 0 description: Total capacity stated by the manufacturer, in Wh. usable_capacity_wh: type: integer minimum: 0 description: > Capacity that can actually be charged and discharged, in Wh. All stored energy values range from 0 to this value. nominal_charge_power_w: type: integer minimum: 0 description: Rated maximum charging power, in W. A magnitude, always positive. nominal_discharge_power_w: type: integer minimum: 0 description: Rated maximum discharging power, in W. A magnitude, always positive. power_measurement_side: type: - string - 'null' enum: - ac - dc - null description: > Where `battery_power_w` is measured: `ac` on the inverter's AC side, `dc` at the battery terminals. Null if the manufacturer does not say. Problem: type: object description: Error details, following RFC 9457 (Problem Details for HTTP APIs). required: - type - title - status - code properties: type: type: string format: uri-reference description: URI identifying the problem type. title: type: string description: Short, human-readable summary of the problem type. status: type: integer description: HTTP status code. code: type: string description: >- Stable, machine-readable error code. See Errors in the API description. detail: type: string description: Human-readable explanation specific to this occurrence. invalid_params: type: array description: Parameters that caused the error, if any. items: type: object required: - name - reason properties: name: type: string reason: type: string responses: Unauthorized: description: The access token is missing, invalid or expired. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://api.kapa.energy/problems/unauthorized title: Unauthorized status: 401 code: unauthorized detail: The access token has expired. NotFound: description: No battery with this id is accessible to the client. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://api.kapa.energy/problems/battery-not-found title: Battery not found status: 404 code: battery_not_found detail: No battery with id bat_9 is accessible to this client. securitySchemes: oauth2: type: oauth2 description: OAuth 2.0 client credentials. Obtain a token from `POST /token`. flows: clientCredentials: tokenUrl: https://api.kapa.energy/token scopes: {} ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.