Proposal: add batteryTemperature to Device model for hardware diagnostics telemetry

[basabot]

Summary

We propose adding batteryTemperature as a hardware telemetry attribute in the SDM Device model.

Motivation

Battery thermal status is critical for field reliability diagnostics (e.g., cold/heat stress, charging issues). This is a cross-domain device health metric and should be standardized in the generic IoT Device model rather than in domain-specific models.

Proposed attribute

• Name: batteryTemperature
• Type: Property (Number)
• Description: Current battery temperature measured by the device.
• unitCode: CEL (degrees Celsius)
• observedAt: standard NGSI-LD observedAt

Example

{
  "id": "urn:ngsi-ld:Device:field-node-044",
  "type": "Device",
  "batteryLevel": {
    "type": "Property",
    "value": 0.76
  },
  "batteryTemperature": {
    "type": "Property",
    "value": 34.1,
    "unitCode": "CEL",
    "observedAt": "2026-04-23T10:00:00Z"
  }
}

Cross-domain relation note

• In implementations, domain entities (e.g., AgriSensor) can reference this hardware twin via the standard refDevice relationship.

Compatibility

Additive and non-breaking.

Maintainer decision requested

• Preferred placement in the current Device schema section?
• Are there any existing equivalent attributes for thermal hardware diagnostics we should align with instead?