It would be according to the rules.
Since Ritual spells only don't use a spell slot when Ritual Cast - Meaning, you spend an additional 10 minutes to cast the spell. If cast without Ritual Casting it, they will use a spell slot like normal.
In BG3 since time is not a factor, it mostly just uses an "In Combat vs Out of Combat" ruling, whereby something like Silence can be cast out of combat for free, but in combat it will consume a spell slot.
As far as Arcane Battery goes, you can toggle the effect off until you're about to use a spell that you'd like to save the spell slot on and then toggle it on as a free action. This will prevent you from consuming the effect on any spells you would not want to use the effect on.
