My car charger can boil water really fast [video] • Hacker News Board

Re: My car charger can boil water really fast [video]

#51

Post by jchw » Sun, Dec 07, 2025, 5:13 PM UTC

maccard wrote: post #47

jchw wrote: post #26

Earlier quoted context omitted.

If people are willing to rewire their homes for kettles, I guess a couple hundred bucks isn't that bad. > limited by the battery's rated number of cycles Obviously the battery should be replaceable. (It should be in most electronics, really...) > The battery's proximity to the heat source wouldn't help. That doesn't seem like a particularly tricky problem to me. The standard kettle already tries as hard as possible t…

> Obviously the battery should be replaceable. (It should be in most electronics, really...) This is super wasteful when we can just hook up a heating element to an insulated tank and keep it hot like Quooker [0] does. Assuming the 3L tank, that would mean probably 20 minutes to heat the tank if it's entirely emptied for the US, but that's how long it would take to boil that water with an electric kettle _anyway_. If…

It doesn't have to be insulated like an insulated water bottle or anything, plastic is good enough for this. I have a cheap 120V kettle, nothing special, probably mostly plastic but with some superficial bits of stainless steel. After bringing a cup of water to a boil you can safely touch the base and anywhere on the kettle itself; there's not even an obvious sign of warmth anywhere except for the lid. If you don't believe me, I do have a thermal camera, but I assume this can be reproduced with most kettles, since it's not like mine is anything special.

Also: a hot water tank is just another type of battery. If it's really well insulated, it might work pretty good, but the self-discharge rate is probably still a lot higher than a lithium ion battery. If you aren't using boiling water every day this seems like it would be very wasteful.

I don't see anything terribly wasteful about the concept of putting batteries in a few more things. They're very recyclable, and already extremely abundant. It's not necessary, but neither is pushing several kW through a kettle just to get water to boil a bit faster. So really, that might be worth interrogating first...

Re: My car charger can boil water really fast [video]

#52

Post by Nextgrid » Sun, Dec 07, 2025, 5:25 PM UTC

quesera wrote: post #50

jchw wrote: post #26

Earlier quoted context omitted.

If people are willing to rewire their homes for kettles, I guess a couple hundred bucks isn't that bad. > limited by the battery's rated number of cycles Obviously the battery should be replaceable. (It should be in most electronics, really...) > The battery's proximity to the heat source wouldn't help. That doesn't seem like a particularly tricky problem to me. The standard kettle already tries as hard as possible t…

I'm in the midst of a kitchen remodel (in 120V land). I decided to pull an extra 240V line to the countertop explicitly for a tea kettle, which I have not purchased yet but seem to be available from Amazon UK for ~2x the price of an ordinary US-market kettle. The most disappointing thing so far is the short list of kettle options that ship from the UK to the US. Also not sure if I should get a UK receptacle (this wou…

The molded, sealed plug of a UK kettle would fare much better in a wet kitchen environment than an aftermarket plug you'd manually install (moisture can get inside and corrode the terminals and connections).

Re: My car charger can boil water really fast [video]

#53

Post by jchw » Sun, Dec 07, 2025, 5:26 PM UTC

quesera wrote: post #50

jchw wrote: post #26

Earlier quoted context omitted.

If people are willing to rewire their homes for kettles, I guess a couple hundred bucks isn't that bad. > limited by the battery's rated number of cycles Obviously the battery should be replaceable. (It should be in most electronics, really...) > The battery's proximity to the heat source wouldn't help. That doesn't seem like a particularly tricky problem to me. The standard kettle already tries as hard as possible t…

I'm in the midst of a kitchen remodel (in 120V land). I decided to pull an extra 240V line to the countertop explicitly for a tea kettle, which I have not purchased yet but seem to be available from Amazon UK for ~2x the price of an ordinary US-market kettle. The most disappointing thing so far is the short list of kettle options that ship from the UK to the US. Also not sure if I should get a UK receptacle (this wou…

Personally I would just wire some NEMA 240V outlet and then have a separate adapter with a pigtail of that receptacle type and a workbox with the UK receptacle. It's a little unwieldy, but it puts the questionable hackery outside the realm of the building inspection at least.

Whether it's actually safe I though, that I am curious. Obviously the kettle can get the 240V potential it expects, but the neutral is center tapped out of the split phase transformer, right? Not sure how people wire this. (Doesn't the neutral wind up having to be one of the hots instead?)

Re: My car charger can boil water really fast [video]

#54

Post by MagnumOpus » Sun, Dec 07, 2025, 5:27 PM UTC

quesera wrote: post #50

jchw wrote: post #26

Earlier quoted context omitted.

If people are willing to rewire their homes for kettles, I guess a couple hundred bucks isn't that bad. > limited by the battery's rated number of cycles Obviously the battery should be replaceable. (It should be in most electronics, really...) > The battery's proximity to the heat source wouldn't help. That doesn't seem like a particularly tricky problem to me. The standard kettle already tries as hard as possible t…

I'm in the midst of a kitchen remodel (in 120V land). I decided to pull an extra 240V line to the countertop explicitly for a tea kettle, which I have not purchased yet but seem to be available from Amazon UK for ~2x the price of an ordinary US-market kettle. The most disappointing thing so far is the short list of kettle options that ship from the UK to the US. Also not sure if I should get a UK receptacle (this wou…

No need to rewire anything - just get a universal plug adapter for NEMA 6-15P (or whatever your kitchen outlet is going to be) from Amazon, plug it onto the UK plug of your kettle, and Bob’s your uncle. (The building inspector doesn’t need to even see your kettle and plug.)

Re: My car charger can boil water really fast [video]

#55

Post by quesera » Sun, Dec 07, 2025, 5:34 PM UTC

Nextgrid wrote: post #52

quesera wrote: post #50

Earlier quoted context omitted.

I'm in the midst of a kitchen remodel (in 120V land). I decided to pull an extra 240V line to the countertop explicitly for a tea kettle, which I have not purchased yet but seem to be available from Amazon UK for ~2x the price of an ordinary US-market kettle. The most disappointing thing so far is the short list of kettle options that ship from the UK to the US. Also not sure if I should get a UK receptacle (this wou…

The molded, sealed plug of a UK kettle would fare much better in a wet kitchen environment than an aftermarket plug you'd manually install (moisture can get inside and corrode the terminals and connections).

I agree. If I replace the wire, I'd get an assembly with the correct US molded plug (NEMA 14-30?), and perform the wire replacement inside the kettle itself. Your reason is good, but I'd do it that way for the aesthetics alone. :)

Re: My car charger can boil water really fast [video]

#56

Post by quesera » Sun, Dec 07, 2025, 5:51 PM UTC

jchw wrote: post #53

quesera wrote: post #50

Earlier quoted context omitted.

I'm in the midst of a kitchen remodel (in 120V land). I decided to pull an extra 240V line to the countertop explicitly for a tea kettle, which I have not purchased yet but seem to be available from Amazon UK for ~2x the price of an ordinary US-market kettle. The most disappointing thing so far is the short list of kettle options that ship from the UK to the US. Also not sure if I should get a UK receptacle (this wou…

Personally I would just wire some NEMA 240V outlet and then have a separate adapter with a pigtail of that receptacle type and a workbox with the UK receptacle. It's a little unwieldy, but it puts the questionable hackery outside the realm of the building inspection at least. Whether it's actually safe I though, that I am curious. Obviously the kettle can get the 240V potential it expects, but the neutral is center t…

Hmm, yeah! I hadn't thought much about the differences between UK and US 240VAC service.

In the US, it's 240V 60Hz, split-phase with center-tapped neutral, and an independent ground wire.

In the UK, it's 240V 50Hz, single-phase with independent neutral and ground.

Frequency difference should be within design tolerance. and if my EE memory serves, the phase difference should be acceptable -- just measured from a different zero reference point. The neutral from the wall would be unused, and the ground would be wired as usual.

I'll think this through thoroughly though, I was definitely glossing over those details, so thank you!

Re: My car charger can boil water really fast [video]

#57

Post by quesera » Sun, Dec 07, 2025, 5:53 PM UTC

MagnumOpus wrote: post #54

quesera wrote: post #50

Earlier quoted context omitted.

I'm in the midst of a kitchen remodel (in 120V land). I decided to pull an extra 240V line to the countertop explicitly for a tea kettle, which I have not purchased yet but seem to be available from Amazon UK for ~2x the price of an ordinary US-market kettle. The most disappointing thing so far is the short list of kettle options that ship from the UK to the US. Also not sure if I should get a UK receptacle (this wou…

No need to rewire anything - just get a universal plug adapter for NEMA 6-15P (or whatever your kitchen outlet is going to be) from Amazon, plug it onto the UK plug of your kettle, and Bob’s your uncle. (The building inspector doesn’t need to even see your kettle and plug.)

That does sound like a much better idea, thank you!

Re: My car charger can boil water really fast [video]

#58

Post by freefaler » Sun, Dec 07, 2025, 6:20 PM UTC

How to overclock your kettle :)

Re: My car charger can boil water really fast [video]

#59

Post by dreamcompiler » Sun, Dec 07, 2025, 7:23 PM UTC

jchw wrote: post #26

Nextgrid wrote: post #12

Earlier quoted context omitted.

It would turn an inert device that costs a couple bucks to manufacture and has affectively no usage limit into a bomb that costs a couple hundred bucks (due to lack of economy of scale) and is limited by the battery's rated number of cycles. The battery's proximity to the heat source wouldn't help.

If people are willing to rewire their homes for kettles, I guess a couple hundred bucks isn't that bad. > limited by the battery's rated number of cycles Obviously the battery should be replaceable. (It should be in most electronics, really...) > The battery's proximity to the heat source wouldn't help. That doesn't seem like a particularly tricky problem to me. The standard kettle already tries as hard as possible t…

The only one I found that was truly battery-powered was the Makita [0]. The $99 Cuisinart I found seems to be a standard electric kettle. Lots of kettles describe themselves as cordless but that does not mean battery-powered; it just means the kettle itself can be removed from a corded base.

I also found a ton of AI-generated link spam pages purporting to be about battery-powered kettles that are all clearly not battery-powered (e.g. [1]). Some of these are 12v powered, but they still contain no batteries. Apparently the adjective cordless confuses AI just like it does people.

Side note: Boiling water takes a lot of energy. You need a big battery; not just a couple of AAs. Any truly battery-powered kettle is going to require a battery at least as big as one for a contractor-grade power tool, and that battery is going to deplete after roughly one boiled pot.

[0] https://www.acmetools.com/makita-40v-max-xgt-hot-water-kettl...

[1] https://activegearreviews.com/best-battery-powered-kettles/

Re: My car charger can boil water really fast [video]

#60

Post by jchw » Sun, Dec 07, 2025, 8:02 PM UTC

quesera wrote: post #56

jchw wrote: post #53

Earlier quoted context omitted.

Personally I would just wire some NEMA 240V outlet and then have a separate adapter with a pigtail of that receptacle type and a workbox with the UK receptacle. It's a little unwieldy, but it puts the questionable hackery outside the realm of the building inspection at least. Whether it's actually safe I though, that I am curious. Obviously the kettle can get the 240V potential it expects, but the neutral is center t…

Hmm, yeah! I hadn't thought much about the differences between UK and US 240VAC service. In the US, it's 240V 60Hz, split-phase with center-tapped neutral, and an independent ground wire. In the UK, it's 240V 50Hz, single-phase with independent neutral and ground. Frequency difference should be within design tolerance. and if my EE memory serves, the phase difference should be acceptable -- just measured from a diffe…

Basically my concern is, ordinarily the potential from neutral to ground would be roughly 0V with some slack. In this case, though, the potential from neutral to ground would necessarily be 120V. I have no idea what the implications of that may be, but it seems important.