New sensor: low_battery_level_threshold

[danielbrunt57]

Checklist

• I have filled out the template to the best of my ability.
• This only contains 1 feature request (if you have multiple feature requests, open one feature request for each feature request).
• This issue is not a duplicate feature request of previous feature requests.

Is your feature request related to a problem? Please describe.

It would be nice to have individual "low-battery" threshold values stored for each device to trigger low-battery notifications . I've not found a low-battery battery notification package or blueprint which addresses how different devices (like my front door lock) do not work well below 75%, others might work okay down to 40% while some may go as low as 20% or lower and still function.

Describe the solution you'd like

Create an additional sensor to store a low-battery level threshold value (%) for the device along with a service to be able to set/change the value, like the one for battery replaced date.

Describe alternatives you've considered

Digging inside existing solutions to hard-code exceptions for the low-battery alert threshold.

Additional context

Perhaps also consider adding an additional true|false sensor which becomes true when battery_level < low_battery_threshold.
Once a low-battery level threshold sensor exists, users could create templated helpers but having the integration do that itself would be useful!

[andrew-codechimp]

I like this idea and something else I'm working on at the moment will tie in well to this.
I'll just have to consider how a default threshold will work.

Moving it to discussion/ideas where I keep longer term features.

[danielbrunt57]

For me, I'd be happy with just an automatically created sensor (or attribute) to store a low battery level trigger value, the initial default value of which is a user configurable system default (20%?) which can be overridden in configuration.yaml and is then prefilled at sensor creation time with the ability for the user to alter before creating a new sensor. Afterwards, a service call/button press can change it like how date works now.

[danielbrunt57]

What about a single sensor like:

sensor.south_patio_blind_battery_information:
  state: <battery_type>
  attributes:
    last_changed: <user_entered_date>
    low_battery_threshold: <default = <system_default=20|configured_default> >
    low_battery: <true|false>  <<-- set by (if possible) whether (battery_level < low_battery_threshold)

[andrew-codechimp]

I'm actually going to go one better than that and echo the current battery sensor into a brand new sensor, with all its attributes plus all of battery notes.
Threshold and low_battery will be new attributes, plus they'll get their own entities for completeness as well.
Probably going to be a few releases as I'll first get the new battery sensor, then work on threshold afterwards.

[andrew-codechimp]

A sneak peak of what this will look like here #570

[andrew-codechimp]

Closing this discussion as it's now in V2 beta and there's larger discussion in sneak peak.

[danielbrunt57]

Thank you for a job well done!