I fully understand that all various settings for datetime is complicated task but it is also unfortunately inconsistent in HA:
Timers as helpers can be set in HH:MM:SS format. However, when I want to set timer from the frontend, I need to use input_datetime helper that is only in HH:MM format. So I managed to switch on the timer using automation reacting on a trigger of a pressed button but limited to HH:MM:
action:
- service: timer.start
data:
duration: '{{ states('input_datetime.toilet_timer') }}'
target:
entity_id: timer.toilet_timer
However, when I am going through the discussions I cannot find an easy way how to make ONE input for the HH:MM:SS format. Yes, it can be managed by two inputs or input and a slider for seconds but that is not as user friendly as I would expect. All ideas welcome.