Hi@RecillM,
Based on the issue that you mentioned, do you want to save the date format like "DD/MM/YY HH:MM" to the Excel table?
Could you please share a bit more about the scenario, how you configure your app?
I suggest you add a DatePicker, HourPicker, MinutePicker to save your date and time.
Here is my scenario, please take a try as below.
Add 3 general columns within the Excel table as follows:

Create an app and connect the Excel table to it.
Insert a Date picker for date select, one Dropdown(HourDropdown1) for hour select, one Dropdown(MinutesDropdown1) for minute select. These three controls are used to store the StartDate column values.
Set the Items property of the HourDropdown1 and MinutesDropdown1 as below:
["00","01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23"] // Set for the HourDropdown1
["00","01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","31","32","33","34","35","36","37","38","39","40","41","42","43","44","45","46","47","48","49","50","51","52","53","54","55","56","57","58","59"] // Set for the MinutesDropdown1
Repeat the above formula for the controls used to store the EndDate column values.
Add a TextInput for entry the 'ID Ticket'.
Add a Button and set the OnSelect property as below:
Patch(
Table1,
Defaults(Table1),
{
StartDate: Text(
StartDatePicker.SelectedDate + Time(
Value(HourDropdown1.Selected.Value),
Value(MinutesDropdown1.Selected.Value),
0
),
"[$-en-US]dd/mm/yy hh:mm"
),
EndDate: Text(
EndDatePicker.SelectedDate + Time(
Value(HourDropdown2.Selected.Value),
Value(MinutesDropdown2.Selected.Value),
0
),
"[$-en-US]dd/mm/yy hh:mm"
),
IDTicket: TextInput1.Text
}
)
Note: Table1 is my Excel table name.
Hope it could help.
Best Regards,
Qi