"Time Charge Complete" only reports finished time, and not how many minutes to finished

[codedesperate]

Hi all,
I'm trying to make an automation that will broadcast to my google speakers when the car is done charging in 10 minutes. (We always use public charging, so we need to move the car).

When looking over the entities, I saw the "Time Charge Complete" showing remaining minutes. So I thought I would just make a trigger that when that sensor states 10 minutes left, the automation should trigger.

However, it seems only the GUI shows remaining time. The actual sensor only reports a timestamp when the charging will be finished. Therefore I cannot trigger on 10 minutes remaining, as it will only report 1 timestamp.

Right now I have my trigger when battery changes from 86% to 87%, because it will take roughly 10min to reach our 90% charge limit.

Does anyone have any idea how I could make a trigger that triggers exactly 10minutes until completion? Maybe somehow you can make a trigger that uses the timestamp from "Time charge complete" minus 10 minutes, but I don't know how.

Ideally, I would love a sensor that actually reports the amounts of minutes left of charging.

[codedesperate]

I had excellent help over at home assistant forums, and I can now make a trigger that triggers 10 minutes before the time_charge_complete value. https://community.home-assistant.io/t/trigger-automation-based-on-time-in-a-sensor-that-writes-a-string/520876/7

I would still love to see a entity provided by this integration that supplies a single value depicting the minutes left of charging.