Electrickery question.

[Ali-G]

Guys (and Gals)
All this talk of amps , ohms and watts goes completely over my head, so I have a question for all you knowledgeable folk on here.
I've been using a domestic kettle in the van and recently I noticed that it is giving my Clayton a bit of a battering. I was going to buy a 12V kettle, but after doing some research on the forum I decided that the best course of action would be to go for a low wattage model instead so I bought a 1.7ltr Outdoor Revolution 1000w kettle from Amazon.
Today I did a test to see how long it would take to boil 1.7 litres in the new kettle, it took just over 9 minutes.
Next I filled my 3000w domestic kettle with 1.7 litres of water and this took 3 3/4 minutes to boil.
So my question is, will running a 1000w kettle for 9 minutes use more or less electricity than running a 3000w kettle for nearly 4 minutes?

Thanks.

 

[t0mb0]

In order to calculate energy used, you just need to multiply the power (w) value which is energy per unit time by the time value (m). In this case doing so will show that the 1000w kettle is using approx 75% of the energy that the 3000w kettle is. This does all assume that the wattage rating of each kettle is accurate.

In terms of estimating how much Ah of a 12v battery that kettle will take, it's (1000*9/60) = 150Wh, assuming a nominal 12v that gives 150/12= 12.5Ah. That's with a perfectly efficient inverter so if we assume an efficiency of 90%, then that gives 12.5/0.9 ~= 14Ah.

Worth mentioning at this point that gas is hugely more energy dense than any battery, so in some sense is a better option for boiling water.

 

[Dellmassive]

It should be the same.

1000w or 3000w... That a factor of 3. (3mins or 9min again a factor of 3)

So 3ish mins at 3000w should equal 9ish mins at 1000w.(a factor of 3)

Boiling water with a heater element is a constant electrical load. And the boiling point of water is also constant.

So the maths should work out the same.

 

[Dellmassive]

as above heating and boiling water is always more efficient with gas.

but - if you have spare electric, say from solar and stored in a battery bank,

then that is cheaper than gas.

so why not.

 

[Dellmassive]

if you want quick boil of water . . .


check this out.

Camping Ideas and Tips

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www.t6forum.com

 

[Sackmycook]

Whats a kettle got to do with a wheel ?

 

[Salty Spuds]

KWH wise, It’ll be about the same. The difference is the current. I’m assuming your Clayton is an inverter running off 12V. To get 3000W from a 12 V supply your inverter will need to pull 3000/12= 250A, that’s assuming your inverter is 100% efficient, which it isn’t, so the current draw from the battery will be in excess of 250A.
To run your 1000W kettle, 1000/12= 83A. Same rules apply regarding efficiency.

So you either pull 250A for 3.75mins or
83A for 9 mins.
So actual battery drain = 250x3.75=937amp minutes
Or
83x9= 747amp minutes.
So not much in it really, the main difference being that the stress & losses in the battery cabling will be lower with the 1000w kettle.
This is back of a fag packet stuff, so only any use as a roughguide.
Ultimately, the amount of energy required to raise a given volume of water from one temperature to another is a constant. How & where the energy comes from is largely irrelevant.

 

[Ali-G]

Thanks very much for the replies everyone.
No gas in the van unfortunately, I've got an induction hob.

 

[Ali-G]

It should be the same.

1000w or 3000w... That a factor of 3. (3mins or 9min again a factor of 3)

So 3ish mins at 3000w should equal 9ish mins at 1000w.(a factor of 3)

Boiling water with a heater element is a constant electrical load. And the boiling point of water is also constant.

So the maths should work out the same.

That what I was thinking Dell but I thought I'd ask just in case it was a bit more complicated than that.

 

[Paynewright]

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[Grim Reaper]

Technology Connections did a video on this a month or so ago.

General concensus was Induction hob was best as this wasted the least energy in blowpast and put almost everything into the kettle itself.

 

[T6Jay]

Obviously you MUST NOT watch the kettle while it boils.

Surprised no one else mentioned this

 

[Dannyb6467]

Obviously you MUST NOT watch the kettle while it boils.

Surprised no one else mentioned this

Mine at home takes 7m 33s to boil 1.78ltrs water if I watch it and only 3m 16s if I don't....I cant work the maths out. On both occasions I used the same kettle????