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wrote:

The Natural Philosopher wrote:

Tim Downie wrote:

As part of her duties as my back-up team when I'm running a long distance
race, my wife may need to boil up stuff for my consumption in the car.

Because of the potential of severe midge attack, this may literally have to
be done in the car with the windows closed (so no gas or other naked flame
suggestions please) .

Would it be worth investing in a reasonably substantial inverter (and
where's the cheapest source for these) that can supply a standard kettle or
might a smaller one powering a 1kw caravan type kettle be more
reasonable/affordable.

Alternatively, are the any good 12V kettles or other electrically heated
pans worth considering. We will probably want to warm up soup as well as
make coffee/tea etc.

My car's a diesel people carrier with a reasonably substantial battery.
Would this cope with boiling a kettle every couple of hours say or should I
invest in a second battery?

The best way is to tap into the engine cooling system or wrap a heat
exchanger round the exhaust pipe :-)

A 3KW kettle bolds in about 3 minutes, sso takes about 9KW minutes...or
0.15Kwh

at 12v that is about 12.5Ah - well within the capability of a car
battery. But not three times in a row with the engine off...

I'd say you will get away with it, BUT I'd invest in a cheap voltmeter
to tell you when to turn the engine back on...or you may find you can't...

A 3kW kettle will take 3000/12 amps from a 12 volt battery, that's 250
amps. It's for a short time but I doubt the battery will like it.

Thats about what the starter motor takes. ;-)

I never said Use a 3KW kettle. use a 500W immersion heater..

50-60A is OK on a battery.

The current you worked out is the current needed to take that much
power from the battery over an hour, if you can wait an hour for you
tea it might be OK!?

I was doing battery depletion calcs, not peak current calcs.

500W or so is the practical limit for any _sustained_ drain from a car
battery.