Device auxiliary battery info messages describe the additional batteries of a device, such as a battery pack.
timestampDateTimeMoment the message refers to, in UTC. FIT stores it as seconds since the FIT epoch (December 31, 1989, 00:00:00 UTC); decoders usually expose it as a regular date.
deviceIndexEnumIndex of the device that produced the data, matching the deviceIndex of a device_info message. The value creator designates the recording device itself.
creatorVoltage of the battery.
batteryStatusEnumBattery state as reported by the device: new, good, ok, low, critical, charging or unknown.
lowunknownnewokcriticalgoodchargingbatteryIdentifierUint8Identifier of the battery.
mesgNumStringGlobal message number identifying the kind of message. Decoders use it to know which profile to apply to the data.