I've been planning a 24v battery system for a camper trailer for a little while now. 24v was chosen as I plan to run a 3kw inverter on it and doing so allows for half the current draw, ergo smaller wiring.
In preparation been measuring 'every day' current draw from household devices, using an "Eve" energy monitor. Over the space of a month, averaging 1-2 coffees a day, the coffee machine has drawn a total of about 500 watts. Tested once only, the air fryer, at 180 degrees for 15 minutes drew 200 watts. I haven't yet tested the induction cooker, but I suspect I'll get a fair bit of mileage out of that too.
I feel like the 8kw/h battery I recently purchased might be a little bit of overkill.