Automations.yaml
- alias: 'Battery Alert'
  initial_state: 'on'
  trigger:
    - platform: state
      entity_id: sensor.battery_status
  action:
    - service: persistent_notification.create
      data_template:
        title: Low Battery levels
        notification_id: low-battery-alert
        message: >
          Check battery: {{ states('sensor.battery_status') }}
    - service: notify.Familje_Alerts
      data_template:
        message: >
          Check battery: {{ states('sensor.battery_status') }}


sensor.yaml
  - platform: template
    sensors:
      battery_status:
        friendly_name: "Battery Status"
        value_template: >-
          {%- set threshold = 30 -%}
          {%- set domains = ['light', 'switch', 'sensor', 'zwave', 'binary_sensor', 'camera'] -%}
          {%- for domain in domains -%}
          {%- for item in states[domain] if ((item.attributes.battery_low is defined and item.attributes['battery_low'] == true) or (item.attributes.battery_level is defined and item.attributes['battery_level'] | int < threshold)) -%}
              {{ item.name }}{%- if not loop.last %}, {% endif -%}
          {%- endfor -%}
          {%- endfor -%}