Home Assistant Blueprint: Low Battery Notificator

low_battery_notificator.yaml

blueprint:
  name: Low Battery Notificator (Exclude List)
  description: >
    Notifies when any battery sensor drops below a configured threshold.
    All battery sensors are monitored except those explicitly excluded.
  domain: automation
  author: Edison Montes @_GeekMD_

  homeassistant:
    min_version: 2024.6.0

  input:
    start_time:
      name: Start Time
      description: Start of the notification window.
      default: "08:00:00"
      selector:
        time: {}

    end_time:
      name: End Time
      description: End of the notification window.
      default: "22:00:00"
      selector:
        time: {}

    battery_level:
      name: Battery Level Threshold
      description: Notify when battery is below this percentage.
      default: 20
      selector:
        number:
          min: 0
          max: 100
          step: 1
          unit_of_measurement: "%"
          mode: slider

    interval_minutes:
      name: Execution Interval
      description: Run every N minutes during the notification window.
      default: 30
      selector:
        number:
          min: 1
          max: 120
          step: 1
          unit_of_measurement: min
          mode: slider

    excluded_entities:
      name: Excluded Entities
      description: Battery sensors to exclude from monitoring.
      default: []
      selector:
        entity:
          multiple: true
          domain: sensor
          device_class: battery

    enable_logging:
      name: Enable Persistent Logging
      description: >
        Create a persistent notification every time low battery devices
        are detected.
      default: false
      selector:
        boolean: {}

    actions:
      name: Actions
      description: >
        Actions to run when low battery devices are detected.
        Use {{ low_battery_devices }} directly in notification messages.
      selector:
        action: {}

trigger:
  # Check at the beginning of the notification window.
  - platform: time
    at: !input start_time
    id: start_time

  # Check at the end of the notification window.
  - platform: time
    at: !input end_time
    id: end_time

  # Check after Home Assistant starts.
  - platform: homeassistant
    event: start
    id: homeassistant_start

  # Used to implement the configurable interval.
  - platform: time_pattern
    minutes: "/1"
    id: interval

  # Execute immediately when any battery sensor changes.
  - platform: event
    event_type: state_changed
    id: battery_state_changed

variables:
  start_time: !input start_time
  end_time: !input end_time
  battery_level: !input battery_level
  interval_minutes: !input interval_minutes
  enable_logging: !input enable_logging
  excluded_entities: !input excluded_entities

  low_battery_devices: >
    {% set threshold = battery_level | int %}
    {% set result = namespace(devices=[]) %}

    {% for sensor in states.sensor %}
      {% if sensor.attributes.device_class == 'battery'
            and sensor.entity_id not in excluded_entities %}

        {% set value = sensor.state %}

        {% if value not in ['unknown', 'unavailable', 'none', ''] %}
          {% set level = value | int(default=101) %}

          {% if 0 <= level < threshold %}
            {% set original_name =
              sensor.attributes.friendly_name | default(sensor.entity_id, true)
            %}

            {% set clean_name =
              original_name
              | regex_replace('(?i)\\b(?:battery|batería)\\b', '')
              | regex_replace('\\s+', ' ')
              | trim
            %}

            {% if clean_name | length == 0 %}
              {% set clean_name = sensor.entity_id %}
            {% endif %}

            {% set result.devices = result.devices + [
              clean_name ~ ' (' ~ level ~ '%)'
            ] %}
          {% endif %}
        {% endif %}
      {% endif %}
    {% endfor %}

    {{ result.devices | join('\n') }}

condition:
  # Only continue when the trigger is relevant.
  - condition: template
    value_template: >
      {% if trigger.id == 'interval' %}
        {% set current_minute =
          (as_timestamp(now()) / 60) | int
        %}
        {{ current_minute % (interval_minutes | int) == 0 }}

      {% elif trigger.id == 'battery_state_changed' %}
        {% set entity_id = trigger.event.data.entity_id | default('') %}
        {% set old_state = trigger.event.data.old_state %}
        {% set new_state = trigger.event.data.new_state %}

        {{ entity_id.startswith('sensor.')
           and new_state is not none
           and new_state.attributes.device_class == 'battery'
           and entity_id not in excluded_entities
           and new_state.state not in ['unknown', 'unavailable', 'none', '']
           and (new_state.state | int(default=101)) < (battery_level | int)
           and (
             old_state is none
             or old_state.state in ['unknown', 'unavailable', 'none', '']
             or (old_state.state | int(default=101)) >= (battery_level | int)
           )
        }}

      {% else %}
        true
      {% endif %}

  # Verify the configured notification window.
  # This also supports windows that cross midnight.
  - condition: template
    value_template: >
      {% set current_time = now().strftime('%H:%M:%S') %}
      {% set start = start_time | string %}
      {% set end = end_time | string %}

      {% if start <= end %}
        {{ start <= current_time <= end }}
      {% else %}
        {{ current_time >= start or current_time <= end }}
      {% endif %}

  # Only execute actions if at least one low battery was found.
  - condition: template
    value_template: >
      {{ low_battery_devices | trim | length > 0 }}

action:
  # Make the rendered value available to user-selected actions.
  - variables:
      low_battery_devices: "{{ low_battery_devices | trim }}"

  - choose:
      - conditions:
          - condition: template
            value_template: "{{ enable_logging | bool }}"
        sequence:
          - service: persistent_notification.create
            data:
              notification_id: low_battery_notificator
              title: "Low Battery Devices"
              message: |-
                Execution time: {{ now().strftime('%Y-%m-%d %H:%M:%S') }}

                Devices below {{ battery_level }}%:

                {{ low_battery_devices }}

  - service: logbook.log
    data:
      name: Low Battery Notificator
      message: |-
        Devices below {{ battery_level }}%:
        {{ low_battery_devices }}

  - choose: []
    default: !input actions

mode: single