Quickest way to boil a kettle, in a car?

[Tim Downie]

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?

Tim

[Jeff]

Jeff

[Gordon Henderson]

I'd be tempted to suggest you invest in a good stainless steel flask - eg

have a one litre one of those and my wife a 0.7 litre, and when properly heated up in the morning, really do keep stuff hot for hours and hours.

It'd save all that faffing about with heaters, spilling liquids, etc.

But if you do go down the electric heater route, remember a 1KW heater is going to suck just over 80 amps out of the system - which with a good battery might be OK, for a very short period of time, but then you have the wory about the wiring being up to the job! (Although I suspect the listtle travel kettles, etc. are much less power than that and designed to work to the 10 amps (or whatever) is avalable via a cigarette lighter socket.

Gordon

[usenet]

Even a 1kW kettle will take (at least, depends on efficiency of inverter, if your using one) 1000/12 amps, which is more than 80 amps. That'll discharge any car bettery pretty rapidly, most are around

40A/h or thereabouts so will be completely and utterly discharged after 30 minutes if in perfect condition. In practice discharging a battery this deeply will do it no good at all.

You'd be better off with one of the 12 volt immersion type heaters which can heat up a mug/cup of liquid fairly quickly with much less power (there's much less to heat up than there is in a kettle).

[Tim Downie]

Hours and hours isn't long enough. Hours and hours and hours would be more like it. I'll need a sustainable supply for at least 24 hours.

Tim

[Tim Downie]

clever.

And would you know offhand if any of these kettle have exposed elements or elements sealed beneath a flat base? (Not much use for heating soup if the elements are exposed)

The reason I *asked* here rather than just googling is because I was hoping to get answers from folk who might actually know something.

Regards

Tim

[Mary Fisher]

> Very clever.

I don't know if that's the same asone we have - it looks like it - the caveat is in the 'mini'.

It does boil water, can't remember if there's an exposed element, but it's only about half a pint at a time. The last time I used ours was about ten years ago. No idea where it is even.

Another problem is that the unit is plastic and soup flavours do tend to linger ...

That's the best I can do, sorry.

Mary

[Mary Fisher]

could, I'd still suggest a separate one for soup.

Overnight. And unbreakable. Wonderful things.

Mary

[Mary Fisher]

Have one for each support stop for each liquid. They're really not expensive and are safer than any form of heating in a car. If they're not opened they will keep liquids warm for well over 24 hours. Even when opened they stay hot for a very long time.

Mary

[Tim Downie]

Well that may be your experience Mary but I've never found thermos flasks able to keep thing *hot* for that long. Warm yes, but there may be times I want something hot as opposed to warm, particularly later on. I'd really rather have the facility to heat things up on the go.

Thanks anyway.

Tim

[Tim Downie]

Why should a SS thermos be better than a glass one from the point of view of heat retention. We have one and I'd say that's it's definitely inferior to our glass ones for keeping things warm. They're also expensive and heavy in comparison.

Well I've never broken a thermos so that aspect doesn't weigh heavily on my mind. ;-)

Tim

[Phil Addison]

I have no idea about cost but I believe outdoor sports shops sell a self heating gizmo for that sort of thing. I have a suspicion the heater comes integral with the food/drink, so your menu may be somewhat limited. I guess it works by allowing two suitable chemicals to mix together and generate heat when you break a seal.

Now, just how DIY do you want this? There is a copious supply of piping hot water in your vehicle cooling system. Surely someone/somewhere has rigged up a means of routing that through a mini heating coil which could be dunked in a steel flask heat up or keep hot the contents? I bet google has some designs already!

Regarding things that plug into the cigar lighter, we bought a mothercare baby-bottle heater which turned out to be a 3" wide plastic strip with an (IIRC) about 50W flat strip heater embedded in it. You wrapped this round the bottle, and it took some 10-15 minutes to heat it to luke warm. That was with about 6 oz of milk in the bottle. Being external to the bottle it is very inefficient, but wrapping the lot in a towel helps, although the instructions forbid that for some reason.

As a cheap and easy solution I would go for the 12V immersion heater. I know someone who has one and apparently it is fine for mug quantities.

Phil The uk.d-i-y FAQ is at

Google uk.d-i-y archive is at NOSPAM from address to email me

[Mary Fisher]

The modern stainless steel ones are unbelievably efficient. I was proved wrong!

Mary

[Gordon Henderson]

You run too much :)

Gordon

[Mary Fisher]

No idea. Some techie hereabouts will know.

Heavy? Oh no! Expensive? No. I paid £4 for our last one. I'm talking about the modern ones, not the prototypes. We have those too.

There's a first time for everything!

Mary

[Bob Mannix]

It is essential to preheat SS flasks by filling them with boiling water for

5 minutes before filling them (assuming you are keeping things hot!). Get one with a valve top so you don't have to actually open it. In my experience (agreeing with Mary again - oh no) they outperform the glass ones in terms of heat retention quite significantly if you do this (yes, even if you do the same to the glass ones). I have both and never use the glass ones any more.

There is also the added benefit (when walking) you can bang them on rocks and only dent them!

[Gordon Henderson]

I've taken soup in mine, but only fine soup, not really chunky stuff! The pouring cap is very good too. Wify bought me one for birthday a couple of years back and I then bought her one after she was jealous of the light weight of mine compared to her heavy old "1st generation SS flask". We've used them on long walks and (whats left of) the contents has still been warm at the end of a long day.

Gordon

[S Viemeister]

I was amazed, the first time I used my new stainless steel flask. My coffee was _too hot to drink_, 6-8 hours after putting it in the flask. Of course, I pre-heated the inside with boiling water before pouring in the piping hot coffee.

A couple of years ago, I bought an insulated, lidded, travel mug from Costco - it has a heating element of some sort, and plugs into a car lighter outlet. I doubt the liquid would boil, but it certainly keeps things very hot. I don't remember the manufacturer and have long since chucked out the packaging, but I could look to see if there's something stamped on the bottom. They were packed in sets of two (different colours), and were amazingly inexpensive.

Sheila

[doozer]

How about a combination of approaches then. Get some quality Thermos flasks (the one we have gives tea easily hot enough to drink well after

24 hours - and l like _hot_ tea) and fill them with hot water.

At first you will be able to just use the water from the Thermos thus saving your battery. When the Thermos water has cooled a little you can top up its warmth with a small plug in heater. Using this approach you can probably use a tiny fraction of the power you would otherwise need heating cold water.

Water at 95 degrees will make tea and soup just as well as water that has boiled / is boiling. Actually boiling the water in this situation is silly because you need to supply a tremendous amount of energy to overcame the hear of vaporization (40.7 KJ/mol) for no gain.

Graham

Tim Downie wrote:

[Bob Mannix]

I meant to add, you can get a 1 cup immersion heater for £4.95 and a 4 cup "coffee pot" for £8.95 from

(beware, it's an addictive site!)

Unfortunately, these items have no image with them.