Is there something like a small battery-operated kettle that could heat a cup or so of water? I need it so I can make oatmeal when I’m at school in the morning because we don’t have a microwave, and I’m not allowed to use the outlets.
You can check the answer of the people under the question at Quora “battery operated water heater for coffee“
Unless there is a distinction between oatmeal and what we British call porage (porridge), this might help. Make it the night before, and leave to soak. Eat it cold: it will be as nutritious, but not warming. I think the Scots word for it is dramach.
Yes, I’ve done it, and yes, it works. I would prefer Joe Ting’s suggestion, but at least now you have several possibilities.
Make the oatmeal at home and put it in a wide mouth double walled stainless steel vacuum container. Eat it at the time you would like to do so. A small portable stove and pot with the dry oatmeal would easily weigh the same as a vacuum flask filled with hot cooked oatmeal. Keeping it simple is best. It would also be cheaper.
I eat at home, so that I can brush my teeth before leaving. For lunch I carry a sandwich if I am away from home.
It’s pretty unlikely that there’s a battery powered kettle, because it would take an awfully large battery to make that work. Batteries are pretty inefficient at power storage on a weight/watt basis. There is a solution you might consider though: flameless ration heaters, otherwise known as ‘MRE heaters’ since they’re included with U.S. military ‘Meal, Ready to Eat’ style ration packs. They’re an insulated pouch containing a small amount of metal powder and salt. You add some water, put your food inside in its own pouch (you’d need to put your oatmeal and water in a baggie), seal it up, the reaction of the metal and water makes a bunch of heat, easily enough to boil water, and in a few minutes you’ve got a cooked meal. Surprisingly, the reaction of the metal powder, salt, and water is a bit like a battery, at least a short circuited one that destroys itself as it discharges.
Flameless ration heater – Wikipedia
I was able to find multiple sites selling these, by searching for ‘MRE heater’.
You’d be better off with a very high quality thermos. The best ones have a vacuum between the inner and outer walls. If you pre-heat the thermos and then fill with boiling water, it will be hot enough for oatmeal or coffee for a few hours.
Canned Sterno has long been used to both heat and keep food warm both indoors and outdoors without using electricity. It does produce a flame which also may not be allowed. But if it is a small, foldable Sterno stove and the canned fuel can be purchased for a modest price at major department stores, camping supply stores and on line and will easily fit into a backpack. One can of Sterno is good for up to two hours of heat and can be extinguished, sealed and reused until the contents have been exhausted.