Template sensor for last battery charge when device unavailable

Configuration
1

Hi all

I’m sure I’m going about this in the wrong way, but for the life of me I can’t figure out the correct way so thought I’d ask for guidance. I want to reflect (in a dashboard) the last known battery charge level for a device that reports ‘unavailable’ when powered off.

It would seem that the post here (Use last value instead of unknown - #19 by 123) describes almost exactly what I’m looking for. I’ve tried adding and modifying this for my device in multiple ways and cannot get it working.

I first thought I could simply add it from Developer Tools > Template, but when adding the code below I get the result ‘trigger is undefined’:

template:
  - trigger:
      - platform: state
        entity_id: sensor.unnamed_room_battery
        not_to:
          - 'unknown'
          - 'unavailable'
    sensor:
      - name: sonos_move_last_battery
        state: '{{ trigger.to_state.state }}'
        device_class: battery
        unit_of_measurement: '%'

Failing that, looked at the reference for templates and added a new template via Settings > helpers and pasted the following into the state template:

- trigger:
      - platform: state
        entity_id: sensor.unnamed_room_battery
        not_to:
          - 'unknown'
          - 'unavailable'

This results in the following in the preview:

Sensor None has device class ‘battery’, state class ‘measurement’ unit ‘%’ and suggested precision ‘None’ thus indicating it has a numeric value; however, it has the non-numeric value: ‘- trigger: - platform: state entity_id: sensor.unnamed_room_battery not_to: - ‘unknown’ - ‘unavailable’’ (<class ‘str’>)

Any obvious pointers on what I’m doing wrong?

Many thanks for any help.

2

The Template Editor is for testing templates, not for testing the configuration of an entire Template Sensor or Trigger-based Template Sensor. It only processes Jinja2 templates, not YAML.

Your first example is fine, but you can’t test {{trigger.to_state.state}} in the Template Editor because the trigger object doesn’t exist until the State Trigger is triggered … and that cannot happen within the Template Editor.

I suggest you add your Trigger-based Template Sensor to the template: section of the configuration.yaml file, or whatever file you’re using for template entities, then restart Home Assistant (if it’s your first Template entity, otherwise you can use Developer Tools → YAML → Reload Template Entities).

Your second example produced an error because a Template Sensor helper (the kind you create via the UI) expects you to supply it with a template only. You gave it a YAML configuration for a trigger.

In addition, a Template Sensor helper doesn’t support the creation of Trigger-based Template Sensors.

3

Thank you! I’m learning, so appreciate the patience. :slight_smile:

1 Like
4

No worries, they’re common mistakes.