As for f1e214f heating up food with coffeemaker (btw, is this possible IRL?) don’t drain any battery charge. I didn’t test other tools that can heat food, but I looked in iuse.cpp and there is no sign of using batteries at all in static bool heat_item(player *p). I think there should be little draining (no more than 3 charges) for this action.
When I lived in the dorms, a lot of people used coffee makers to make things like ramen at the very least. I never tried it, so I’m not sure how creative they got, but yes. IRL, you can cook with a coffeemaker. =p
Also, most recipes that use things like hotplates do use up charges. I imagine the coffeemaker not using up charges is a bug/oversight.
Crafting with this tools (e.g. boiling water in coffeemaker) correctly use charges. Only heating up food don’t.
This should be in the garage thread, not in the drawing board one.
I didn’t know if this was a bug or a feature, so I posted it here. Sorry if I was wrong.