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24 VDC appliances?

On Wed, 14 Jan 2004 12:36:42 -0800, "Rod McInnis"
wrote:

"Larry W4CSC" wrote in message
...

For those times, perhaps what is needed is a black plastic water
heater you could haul up the mainmast to heat some medium for the
night.

What you would need is thermal mass. The key word here is "mass". It will
take a lot of it, if you intend to pull heat out of it all night long. And
it will be heavy. How much weight would you feel comfortable hauling up the
mast?

How about we transfer the heat into the thousands of pounds of lead in
the KEEL? Is that mass enough??...(c;

I was referring to a way we could heat the cabin in the DAYTIME, to
reduce the cost of load of heating it, not eliminate it. If you
pumped air from the cabin up into a black plastic bag, of sorts,
exposed to the sun, the air coming back out into the cabin would be
more than enough to heat the boat in the daytime....for free.

I know someone who has homemade panels hanging from the
sunny side window sills to the ground below.

This works great IF you have a sunny exposure BELOW the area where you use
or store the energy. I have known people who live on a steep hill with a
southern exposure (northern hemisphere, which means that the slope gets a
lot of sun). It is somewhat common to construct a solar heater out of black
ABS pipe that runs down the hill a ways. Heating swimming pools is common,
but I know one person who had copper pipes embedded in the concrete slab of
his home and ciculated the warm water to heat the slab.

Agreed, hence the FAN to overcome the problem, forcing air to
circulate against its will into and out of the bag.

The key is that warm air/water will rise, so if the source of heat is lower
you can create a natural flow of water. If the source of heat is above,
then you will need to pump the water, and you may end up using more energy
pumping than you would have heating.

Rod

Pumping air into the thing is easy. 12V muffin fans draw almost no
power and move a LOT of air.

24 VDC appliances?

On Tue, 13 Jan 2004 00:58:42 GMT, Rick
wrote:

While I have not bothered to search, the selection of marine
equipment available in 24VDC must be very very small. Most
all little boats use 12VDC, most larger boats use
110/220/480VAC.

Many mid-size yachts (45-80 ft ) have dual 12/24 V systems. 12 V for
electronics that are low-power and often don't come in 24V versions,
24V for Bow/sternthrusters, windlasses, electrical winches etc. Mainly
too keep the cables reasonable.

/Marcus

--
Marcus AAkesson
Gothenburg Callsigns: SM6XFN & SB4779
Sweden
Keep the world clean - no HTML in news or mail !

24 VDC appliances?

I knew what Larry intended: why didn't you?

Brian W

On Wed, 14 Jan 2004 20:59:50 GMT, "Morex Support"
wrote:

Fatal Error.
The heating element is resistive. 120V 2KW element is approx 7 ohms. Reduce
voltage to 24 v and current draw drops to 3.5 amps. Power is not a constant.
"Larry W4CSC" wrote in message
...
Wouldn't actually make much of a difference. If the 2KW water heater
were running on 12V, it would draw 167A. On 24V it would still draw
83.3A, draining the batteries in a matter of minutes, not hours......

24 VDC appliances?

If y'all would just hang on for the next design generation of auto
electronics, you might could use the 42 volt electrics.....

Brian Whatcott Altus OK

On Wed, 14 Jan 2004 17:12:08 -0500, "Bryan B"
wrote:

We use both 12 and 24 systems. They higher the required amperage the better
it is to use a higher voltage. We run winches, fridge, and autopilot hyd
motor with 24 volt. All else is 12v.
We use two 12 volt banks and one very large 24 volt bank. Charging is from
both 12 and 24v HO alternators but are getting ready to add additional
charging systems.

Gas for cooking, diesel for heating. Hate to run a $20k motor to heat the
cabin.

Good luck,

B
"misia" wrote in message
mail.from.there...
On my new boat I will have a powerfull 24VDC battery bank charged by a
diesel generator and auxiliary sources.

I did a bit of search but couldn't find much- are there any 24 VDC
appliances such as cooker/oven, fridge, AC and water heater you could
recommend?

I know I can run standard items through power inverter but I would
prefer not to do it for the sake of reliability/efficiency/cost. I want
to go totally electric (no gas)

Regards Mi

24 VDC appliances?

"Morex Support" wrote in message
able.rogers.com...
Fatal Error.
The heating element is resistive. 120V 2KW element is approx 7 ohms.
Reduce
voltage to 24 v and current draw drops to 3.5 amps. Power is not a
constant.

I am sure that Larry wasn't suggesting that a 120 volt heating element be
used at 12 volts. What he was suggesting is that IF a 24 volt equivalent
device could be found, then it would draw 83 amps.

Oh, and by the way, your example is way off also. In most cases, heating
elements have a dramatic increase in resistance as they heat up. The element
in question may have a resistance of 7 ohms when it is dissipating 2KW, but
if you drop the voltage the resistance will drop also.

This resistance change is even more dramatic on a light bulb. Take a low
wattage light bulb and measure the resistance when it is cold and you may be
surprised! This is why cutting the voltage in half to incandescent lights
does NOT cut the current in half!

Rod McInnis

24 VDC appliances?

"Bryan B" wrote in message
...
We use both 12 and 24 systems.

Just out of curiosity, who is "we" ?

Rod