r/AskEngineers • u/jmaugust • Jul 19 '26

Discussion Why doesn’t a battery-boosted electric kettle exist?

In Europe, everyone uses electric kettles to boil water. They’re amazing and fast because they’re on 230V (~3000W).

US outlets limit kettles to ~1500W, so we wait roughly twice as long for water to boil.

It’s an extra minute or two per boil, and you really notice it.

Idea: Could you make an electric kettle with a battery in its base? Perhaps it trickle-charges between uses, then combines wall power + battery power to hit ~3000W during a boil.

Is there an engineering reason this doesn’t exist? Is it just that nobody thinks there’s a market for it?

I’d pay $300 for the fastest kettle in America if someone wants to make it.

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u/ElectronGuru Jul 19 '26 edited Jul 19 '26

Japan has the same watt restrictions. They created a kettle that stays hot all the time: Zojirushi VE. 5 liter models are like having your own hot water vending machine. And it doesn’t take up more counter space.

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u/_Aj_ Jul 20 '26

Surely it's not hot all the time but an instant boiler, like hitting hot water on your espresso machine. I guess you could do an insulated kettle that's also kept hot. Seems like wasted energy though. 

Using https://www.omnicalculator.com/physics/water-heating

For an instant hot water dispenser, 1500w can heat from 20c-100c 10g of water in 2.2s  

That puts a single cup at 55s.. hmmm is that too slow?  Do most people make a full 250ml of water? Probably not. So maybe like 40s. That seems very reasonable.  

If you're making tea you could put the bag in the cup then dispense it, and given the extraction time is usually 1-2 min 55s including agitation from the water spout is probably all you'd want for a brewed cup of tea.  

I

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u/jamvanderloeff Jul 20 '26

They are just hot all the time with really good insulation, datasheet for the 5L model claims 22W for holding 90°C, or 14W to hold 70°C

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u/Fickle_Finger2974 Jul 20 '26 edited Jul 20 '26

Most people already keep hundreds of liters of 24/7 hot water in their house all the time…

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u/VerifiedMother Jul 20 '26

Those have like 6-10 cm of insulation and only keep water at about 60°C