Look, the point was whether or not it would be okay to put batteries on it, not whether it would keep a drink warm for 12 hours. If the base is cool to the touch, I think it will be completely fine for batteries to be near it. If anything, making sure they're safe from shorting is probably a bigger concern.

> You're technically correct, the worst kind of correct.

The point wasn't to be technically correct, it's to point out that you can compare the properties of the two types of batteries like-for-like and realize that for many people interested in a faster kettle the boiling water tank idea might not be great. In America most homes have a water heater and it has to contend with the same sort of problem, only we use hot water multiple times a day every day (and at least in the Midwest, use LNG for heating it a lot of the time, which makes it economical if not particularly environmentally friendly.)

> It takes ~320 kJ of energy to bring a litre of water from room temp to boiling, no matter what way you spin it. The difference between pushing 1500w or 3kW into the hot plate is "how quickly do you get to boiling", and has basically no bearing on the total amount of energy used to boil the water. Running a 1500w kettle for twice as long will use the same amount of energy, from the same source.

Well duh. My very first post in this thread is estimating how much energy is required for a typical kettle to bring a U.S. cup of water to a boil. (Though obviously in reality you have to account for losses.)

My point here is that (a relatively small niche of) people are already doing crazy things like rewiring their houses (in America) to push pretty absurd power into kettles just boil water slightly faster, a time save that literally only even matters if you sit there and wait idly while the water heats up. The problem I have isn't that higher wattage kettles are somehow bad, it's that all of this time, effort and money for a time save measured in minutes is crazy. And it's the same for strapping batteries to a kettle or for keeping a water tank of boiling water too. I wouldn't bother with any of them, and don't. (But, as I opened this thread with, seeing how crazy people get over this, I do remain surprised at the relatively few battery kettles on the market.)

> Using consumable li-ion/alkaline batteries to supplement that energy is _terribly_ wasteful - we've been through the "reduce reuse recycle" loop already with waste, lets not do the same thing with rare earth metals to avoid running a single cable to household appliances.

I just counted and the room I'm currently standing in has 8 separate high capacity lithium ion batteries. We put batteries in our power tools, laptops, vacuum cleaners, tooth brushes, game controllers, wireless computer peripherals, air compressors, UPS units, the phone someone is currently reading this comment on, air dusters, garden lighting and certainly much more. Almost everything with electronics in it has batteries for something (if you inlcude smaller ones like clock batteries), and more often than ever, high capacity ones no less.

A battery operated kettle will forever be an expensive niche product, and it wouldn't even use that much battery in the first place. The environmental impact of all of those batteries would struggle to get to the level of 100 electric vehicles, and yet we are selling over 10 million of those per year.

Of all of the contrived and silly arguments, this is by far the most contrived and silliest of all of them.