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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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16th Nov 2016, 1:39 pm | #1 |
Heptode
Join Date: Mar 2010
Location: Hemel Hempstead, Hertfordshire, UK.
Posts: 840
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12 Volt car kettles
Back in the early 80's my Dad picked up one of these to make a brew en route to our holiday in Devon. It sounded so civil, a fresh brewed cuppa - not a flask. So to help it we filled a flask with hot water and stopped with the engine running to make the tea. Well we thought it was not working - just did not heat the water at all. So in the end we started driving and my Mum had the kettle between her feet 'boiling'. After another 15 minutes we pulled over to see if it had heated the water further - it had, but hardly. We threw the water out and never used it again.
Well, digging in the loft, guess what I found! The car kettle - still mint! So, did anyone here use one of these? Did it boil your water? I'm going to set it up on a PSU to see how long it takes to boil one cup of water at 13 V - if at all. If not, I will be cranking up the voltage! |
16th Nov 2016, 1:45 pm | #2 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,081
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Re: 12 Volt car kettles
I wonder if it was rated as a truck driver's kettle so could cope with 24volts, (or 12volts if you were prepared to wait an hour!)
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16th Nov 2016, 1:50 pm | #3 | |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: 12 Volt car kettles
Quote:
Lawrence. |
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16th Nov 2016, 2:14 pm | #4 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
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Re: 12 Volt car kettles
Just measure its resistance! That'll tell you how much power it'll dissipate at 12-14 volts from which you can stab a guess at how long it'll take to boil a cupful.
4.2J/g/C is the magic multiplier.
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16th Nov 2016, 4:06 pm | #5 |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,129
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Re: 12 Volt car kettles
Car kettles varied in current consumption and therefore in speed of boiling.
Most were about 15 amps and very slow to boil but had the advantage of plugging into the cigar lighter. The flexible cord supplied with such kettles is often very undersized and gets alarmingly hot, as well as wasting power. It can be worth replacing it with something more substantial. Heavy duty versions used 30 amps or more but needed a direct connection to the battery. 24 volt kettles for use in HGVs are often 20 amps or more and boil in a reasonable time. I know of someone who routinely uses a 24 volt, 600 watt kettle at home and finds it satisfactory. They have no mains services but a large battery bank charged by renewables. When the battery is well charged it may as well be used, with bottled gas being the alternative. |
16th Nov 2016, 5:17 pm | #6 |
Guest
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Re: 12 Volt car kettles
My motorcycle has a cigarette lighter socket (now called the more PC DC outlet) rated at 10A... Your average mains kettle is 2 to 3kW and for 10A at 12V (say 14 on charge) that would be 140W, some 15 to 20 times longer to boil. If I want a cuppa I stop at a proper greasy spoon (support the independents), rather tricky making coffee on a bike, let alone drinking it.
Vaguely back on topic, what ever happened to the proposed 42V 'car electrical' system (36V off charge)? That would make in vehicle kettles viable. |
16th Nov 2016, 5:30 pm | #7 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,316
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Re: 12 Volt car kettles
The only vehicle I know of that uses 36V is my wife's "Powabike" electric bike.
I suppose things could be improved by using a heating element in a Thermos flask to minimise heat loss. The long time to boll of such low-power appliances really highlights the nonsense of the EC's proposal to ban high speed kettles to save energy. Last edited by emeritus; 16th Nov 2016 at 5:35 pm. |
16th Nov 2016, 5:31 pm | #8 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,118
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Re: 12 Volt car kettles
Not a kettle as such but I did have (probably still do somewhere in the black hole that I call a house) a car version of those immersion heaters to stick into a cup. It was fitted with a standard car accessory plug (AKA cigar-lighter type plug), so I assume it was intended for 12V, but I had exactly the same problem as Ian - it took longer to heat up than it did for my patience to run out. And like him, I never tried it again.
By the way, aren't car accessory sockets rated at a maximum of 5A? I know the stand-alone one I have for my workshop 12V supply is.
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16th Nov 2016, 7:10 pm | #9 |
Nonode
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 2,129
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Re: 12 Volt car kettles
The proposed change to 36/42 volts for vehicle electrics seems to have sunk without trace. Such a voltage would indeed make a kettle more viable.
Some lightweight electrically propelled vehicles such as mobility scooters, golf carts, and electric cycles are 36 volts, but engine driven cars have remained at 12 volts. |
16th Nov 2016, 7:11 pm | #10 |
Dekatron
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
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Re: 12 Volt car kettles
Maplin sell an inverter rated at 300W continuous that can be run either via direct connection to the battery or via a standard cigarette lighter plug, which indicates at least 25A being drawn. The catalogue warns that their higher power ones must not be connected via the lighter socket, but must be connected directly to the battery.
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16th Nov 2016, 9:26 pm | #11 |
Dekatron
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,738
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Re: 12 Volt car kettles
I've got one somewhere, never used, and doubt it ever will be, but they're widely available at well under a tenner. To quote one typical listing:
Quote: 8-< 12v In Car Hot Water Heater Element - Coffee, Tea, Baby Bottle Warmer ideal for the driver on the move will heat water in minutes ideal for warming baby bottles, soup coffee, tea perfect for camping. Not recommended for lorry drivers as this is 12v only not 24v which most trucks are 8-< End quote. No mention of the wattage used.
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17th Nov 2016, 12:21 am | #12 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
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Re: 12 Volt car kettles
A quick calculation suggests that a 120W heater would boil 250ml (a cupful) of 20C water in about 12 minutes with no heat loss. Say 15 minutes or so for the heater dunked in an insulated mug sort of container.
Long enough to get rather fed up!
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17th Nov 2016, 2:04 pm | #13 |
Pentode
Join Date: Jul 2009
Location: Hucknall, Nottinghamshire, UK.
Posts: 223
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Re: 12 Volt car kettles
When I was in the Army in Germany the 432 APC had a square 24 volts electric kettle, (Boiling Vessel = BV for the use of) the K60 multi-fuel 6 cylinder opposed piston engine had to be kept running. It was the driver/radio/radar opps (me) job to keep in topped up with water & woe betide you if it boiled dry & ejected it's plug as you had to wait ages for it to cool down...
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