Alerts when batteries are getting old

[aherbjornsen]

I just went around my house replacing CR2032 batteries in four different sensors, and I noticed that:

a) They do not really report remaining battery percentage in any useful way. One of the sensors died while saying battery 20%, another one is outdoors and went up and down from 5 to 20% depending on outside temperature and then suddenly died.

b) They had last been replaced 14-16 months earlier, so establishing a routine to change them every 10-12 months seems like a good idea.

So I wonder if someone has any suggestions for an automation that would send notifications if last_replaced for my CR2032 devices was more than x days ago?

[andrew-codechimp]

Hi,
That's not possible today with Battery Notes but you can query the last_replaced fields.
I just knocked up a quick template with the help of some AI. It ignores the battery type, just looking at the last_replaced but it's maybe a starting point.

{% set cutoff = (now() - timedelta(days=365)) | as_timestamp %}

{% for s in states -%}
  {% if '_battery_last_replaced' in s.entity_id and s.state not in ['unknown', 'unavailable', ''] -%}
    {% set dt = s.state | as_datetime | as_timestamp -%}
    {% if dt < cutoff %}
{{ s.entity_id }}
    {%- endif -%}
  {% endif -%}
{% endfor %}

[aherbjornsen]

Yes, thanks for the fast and helpful response, it is a good starting point. I'll need to add some filters for inactive sensors and battery type but it should be fairly simple to implement.
What I would really like is to have a "battery max age" value on each sensor, so I did not have to implement this logic in a separate script. But I see that this might be a lot of work for something that only I would use ;-)

[andrew-codechimp]

I think if I were going to do anything with this I'd make a new service/event trigger like battery_not_reported, that way you'd get event's with all the data about the battery so you could make decisions on whether to create notifications/todo's etc.
I've not had the request before so probably a bit of an edge case but I'll give it some thought for the future.