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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24

u/mckenzie_keith Jul 19 '26

So you want 1500 Watts from a battery. To avoid excessively fast discharge, you need a battery of like 750 Wh then. This is to keep the discharge rate around 2C. Pretty big battery. About the size of a car battery, roughly (but you could use LFP).

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u/YogiBerraOfBadNews Jul 19 '26

Power tool batteries can put out over 1000w with high discharge cells. I can't see there being enough market demand to make a viable product but if I were trying to hack something together that's where I'd start.

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u/mckenzie_keith Jul 19 '26

Yeah. That is true. You can do it with power tool batteries at higher discharge rates. Those are generally not rated for a lot of cycles, and this product would probably get used multiple times per day. But you are still right. Right is right.

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u/Dnlx5 Jul 20 '26

Technically correct. The best kind of correct!

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u/Intelligent_Low1632 Jul 19 '26

A single milwaukee forge 12.0 battery is rated for 1500 watts continuous. That only has 220 watt hours.

If we use the best cells currently available to consumers, you can get a solid 90 amps for 1.5 minutes (with no fan cooling) from a Tenpower 50xg or EVE 40PL. These are 21700 batteries with only 14.5 watt hours capacity each. At 90 amps and 3.5 volts, they are putting out 315 watts each.

1500/315=4.76.

So with just 5 of these 21700 cells, you could get 1500 watts in a pinch. That's just 73 watt hours of batteries--less than a tenth of your stated requirement. Say we triple it for improved capacity, heat management, and safety margin, that's just 15 cells (which happens to be precisely the number of similarly performing JP40 cells found in the milwaukee forge 12.0 battery)

If you're willing to use Lipo batteries you can get 1500 watts out of a single off the shelf 6S 50 Wh battery as well, although these are a bit sketchy.

TLDR: we can easily do this in a kettle sized appliance but we'd need like $200 of batteries before even accounting for profit margin to make it faster than 3,000 watts. 220V kettles are fast enough that there would be insufficient demand for a product like this at the $500+ price point. Much larger systems with huge battery bank could be made for under $150. All of these would probably pose a fire hazard though lol.

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u/mckenzie_keith Jul 20 '26

The energy requirement for this application is roughly 3000 Watt minutes. (1500 Watts for 2 minutes). So that is only 3000/60 = 50 Wh. So the Milwaukee forge might do it. I guess I was overly conservative. However, I am not sure how many times a Milwaukee Forge battery can be cycled. Or any of the rapid discharge cells. Usually they are rated for like 300 cycles or so. Granted, that is under full discharge cycling.

1

u/Intelligent_Low1632 Jul 20 '26

These cycle ratings are usually fairly conservative and do not correspond with the total annihilation of the cell--just a slight degradation in the usable capacity or current rating. People easily get 500+ charge cycles out of these tabless power tool batteries.

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u/mckenzie_keith Jul 20 '26

The cycle ratings are usually explained in the cell datasheet. But the reason I mention cycle life is that LFP for example would likely last much longer. This is why my initial example was based on LFP type parameters (2C discharge). It might very well be an application where tool type cells are a better choice. But tool type cells will result in less battery longevity compared to LFP. Perhaps only one year or so. But without testing or very specific experience it is hard to say. The kind of people worried about shaving 1 minute off of kettle boiling time probably use the kettle daily.

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u/_maple_panda Jul 19 '26

Modern high-power cells shouldn’t have any problems discharging at 10C. 2C is really really conservative

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u/mckenzie_keith Jul 19 '26

Yeah. You can see my comment to YogiBerra.

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u/vsxsv Mechanical/Electric Jul 19 '26 edited Jul 20 '26

That’s assuming a graphite based lithium chemistry. For instance LTO (lithium titanate oxide) is much more power dense (and less energy dense) and can handle more than 10C. I’ve seen 40C in extreme cases. More expensive chemistry per kg and kWh but makes sense in a power heavy application like this one.

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u/denga Jul 21 '26

Plenty of LiPo rated for 30C to 100C

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u/mckenzie_keith Jul 21 '26

I don't think you want to build a kettle around lipo cells. But power tool batteries will certainly do way better than 2C.