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Read telemetry history or the latest measurement for a battery. The latest response has a null point if Kapa has not received a measurement yet.

Measurements

  • 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.

Time conventions

  • 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 events

Receive new telemetry points at your HTTPS endpoint. Delivery is at least once and not ordered. Deduplicate with event_id and order data with measured_at. Webhook registration is not covered by this version of the API.

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.