Question about Dreame L20 Ultra

I don't currently see this option in the application

Have a look at the two instructions. I find the question itself very specific. After a job, if the appliance has a low battery anyway, it will automatically want to go back and recharge. The robot also wants to vacuum the dirt it has picked up in the base station. I haven't found anything in the Dreame menu either. Then start cleaning just before the low tariff and you're good to go.
In addition to vacuuming, the pads are also washed, cleaned and dried in the base.

The robot always goes to the charging station for charging after cleaning.
What you want is not possible.
Then the station itself would have to have no power during this time and the vacuum cleaner would not run without the station.

Since a mobile battery is installed here, I was surprised and did the maths:
If you charge it daily from 0% battery to 100%: (I let it clean 110m2 3 times a week (flat 170m2) and don't even get it to 40%)
then you save 15 cents a year. And I'm assuming that you don't have it mop every day and that at 0%. So you would realistically save 5-10 cents.

Brutal savings.