Battery Protocol

MAVLink provides a number of messages for providing battery information:

The messages should be sent individually for each battery in the system (the messages have an instance id field that is used to identify the corresponding battery). It is up to the GCS to provide an appropriate mechanism that allows the user to assess the aggregate battery status on systems that have multiple batteries.

There is no standardized mechanism to report the "aggregate" battery state on a multi-battery system. A GCS is expected to provide enough information from the individual battery reports to allow a user to make a reasonable assessment of vehicle battery status.

Message/Enum Summary

MessageDescription
BATTERY_STATUSBattery message used for frequent status update - e.g. of current capacity, voltages, faults, etc.
BATTERY_INFO (WIP)Battery message used for invariant or infrequently changing data - e.g. battery name, battery full/empty capacity and voltages etc.
EnumDescription
MAV_BATTERY_FAULTFault/health indications.
MAV_BATTERY_MODEBattery mode.

Battery Components

Batteries that are connected to a flight controller via a non-MAVLink bus are treated as part of the flight controller component. Specifically, the battery messages are emitted with the autopilot system and component ids, and the MAV_TYPE for the type of vehicle.

Batteries that are distinct components on the MAVLink network must:

Ground stations (and other components) that are interested in battery messages should differentiate batteries based on BATTERY_STATUS.id/BATTERY_INFO.id.

A Note on SYS_STATUS

SYS_STATUS contains three battery information fields: voltage_battery, current_battery, battery_remaining.

On a single-battery system these usually provide the same information as the BATTERY_STATUS message.

On multi-battery systems the values are not standardised, and depend on the flight stack and/or flight stack configuration. For example, a system may report the same information as the first BATTERY_STATUS, allow the user to configure which battery is reported (i.e. with a parameter), report the battery with the lowest remaining capacity.

GCS should not rely on the value of SYS_STATUS. However it cannot be removed because it is used for battery reporting on many legacy systems (e.g. On-screen displays).

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