AlphaESS Smile T10 - integration - Charles Gillander

I am struggling to understand the correct syntax to issue start- and end-times for battery charging / discharging using the charlesgillander integration. Particularly how many and what quotes are needed when specifying a sensor with a time stamp.
Is it fully quoted as in:
dp1start: "'{{states('sensor.battery_discharge_start_time')}}'"

Or is it only double quoted, as in:
dp1start: "{{states('sensor.battery_discharge_start_time')}}"

Or only singly:
dp1start: '{{states('sensor.battery_discharge_start_time')}}'

And perhaps more importantly- why ?

Thanks in advance,
Bernard

Today it is the first time that the template sensors with start and end times, have been pushed thru to the battery. The changes I made were to calculate the template sensors as string variables containing the start and end times dynamically on the next quarter like:
12:15 and 16:00
or
13:45 and 16:15

with the quarters always one of :00``, :15``, :30 or :45

Then I have an automation push these numbers to the battery control using the Alpha ESS: Set Battery Charge action with Charging Period 1 Start:
{{states('sensor.battery_charge_start_time')}}
and Charging Period 1 End:
{{states('sensor.battery_charge_end_time')}}

What worked was to enter them without any quotes.

Rgds,
Bernard