When battery is normal, the sensor uses tunex_7f01; however, when the battery is low, ID starts oscillating between tunex_7f01 and tunex_7f02 and, if almost discharged, only tunex_7f02 will appear.
HA template for battery sensor is defined as following. Automation can be set with numeric_state below 100.
fridge_sensor_battery:
friendly_name: Fridge Sensor Battery
value_template: >
{% if is_state('sensor.tunex_7f01_bat', 'unknown') or is_state('sensor.tunex_7f01_bat','low') or is_state('sensor.tunex_7f02_bat','low') %}
0
{% elif is_state('sensor.tunex_7f01_bat','ok')%}
100
{% else %}
50
{% endif %}
icon_template: >
{% if is_state('sensor.tunex_7f01_bat', 'unknown') or is_state('sensor.tunex_7f01_bat','low') or is_state('sensor.tunex_7f02_bat','low') %}
mdi:battery-charging-wireless-outline
{% else %}
mdi:battery
{% endif %}
unit_of_measurement: '%'