Heater - Page 2

**daveb** · 11-11-2009, 03:02 PM

Quote:

Originally Posted by geoffff

Quote:

Originally Posted by Bronco_hauler

I have a 120V ceramic heater that I've used once or twice, but I'm more and more hesitant to use it since it uses a fair amount of power itself and I need to leave the inverter running. I have been eyeing 12V mattress heating pads. They have a built in thermostat (based upon a numerical setting, not a temperature) and plug into cigarette lighter sockets. That coupled with a good down comforter should keep me and the wife snug.

Herb

I haven't considered going electric because I couldn't imagine the house battery having enough energy for heating. Does it work for you? Or are you running a generator overnight?

Actually, let me try some estimating here: A 4-D house battery is rated something like 200 amp hours. If you sleep 8 hours, that's 200/8 = 25 amps. 25 amps at 12 volts is 300 watts.

So, (if I've done my math right) the battery should have just enough power to produce 300 watts of heat overnight. That's enough for an electric blanket (something in the 50-200 watt range), but nothing like a space heater (more like 1500 watts).

-- Geoff

Have you guys taken into account that taking a battery down past 50% on a regular basis isn't real good for it or did you factor that in?

**BroncoHauler** · 11-11-2009, 03:22 PM

A couple of points of clarification on my thought process.

The ceramic heater I have is 120V, not 12V. FWIW, it draws 12.5A when on. It has a thermostat so it won't be on all the time. If it's on 50% of the time over an 8 hour period, that's 50A-hrs.

The mattress warmer (42" x 60" - I haven't measure what size I'd really need) draws 6.3A when on. I have no direct experience with these so I don't know what the duty cycle is, but they do cycle on and off depending on the temperature and the heat setting you select. Making a BIG assumption of a 50% duty cycle and an 8 hour period comes up to 25.2A-hrs. Well within my comfort zone for drawing from a battery (famous last words?).

It's because of my concerns over the ceramic heater's current draw is the reason I'm considering the mattress warmer.

Example mattress warmer: http://www.electrowarmth.com/fleet.php

Herb

geoffff · 11-11-2009, 03:58 PM

Quote:

Originally Posted by daveb

Have you guys taken into account that taking a battery down past 50% on a regular basis isn't real good for it or did you factor that in?

No, I didn't. I suspect that battery rating I used (from a quick internet search) might be full discharge which isn't a good idea.

Good seeing the estimate discussion. I'd be curious to see how it works out with real-life experiences.

-- Geoff

jage · 11-11-2009, 04:48 PM

If you search for "toaster" and author "jage" I think there is a good discussion of amp-hours that I learned from long ago.

zippy · 11-11-2009, 05:19 PM

How about a sun shower type hot water bottle?

billwilson · 11-11-2009, 05:36 PM

Quote:

Originally Posted by dowgars

Geoffff: They are installing a propex propane furnace in the rig. It is small. We will see how quiet and adequate. If anyone else has ideas please let us know. Best, RD

Check out http://www.thesamba.com
search Propex
Heaps of positive reviews

also check out Karls website http://www.westyventures.com/propex.html

there are TWO SIZES of propex FYI

zippy · 11-12-2009, 06:41 AM

I don't believe the propex is necessarily a better choice than a US furnance like the atwood. But it has more installation options (at twice the price). What I don't like about US designs is that everything is through the outer wall of the vehicle. I'm surprised RV cupholders don't require cutting a hole in the side of the vehicle......

Trek520 · 11-12-2009, 03:31 PM

Well this is why I like having a SMB,plenty of help from the members here.
Like most of you I wouldn't use the heater while sleeping,I have a very good sleeping bag and it sure is better to be in the SMB than on the ground.
I thank you all for your input and make a choice soon.
Hopefully I might spend some time in the Fl. Keys this winter, where it won't be a problem.
Thanks again,
Ed

coyotearms · 02-03-2011, 08:02 AM

Quote:

Originally Posted by BroncoHauler

A couple of points of clarification on my thought process.

The ceramic heater I have is 120V, not 12V. FWIW, it draws 12.5A when on. It has a thermostat so it won't be on all the time. If it's on 50% of the time over an 8 hour period, that's 50A-hrs.

This is a very old post, but I thought it would be good to clarify a bit for readers who find it. If the ceramic heater referred to is pulling 12.5 amps @ 120 VAC, it will be pulling about (120/12)*12.5 = 125 DC amps from the 12V batteries. I have the 2.5 gal Insinkerator 120 VAC hot water heater, rated at 1500 W hooked up to the inverter. When it is on and heating water while not hooked up to shore power, i.e. getting AC power from the inverter, according to the display for Blue Sky Solar setup, it draws 160 amps from the batteries---that's big time current!

geoffff · 02-03-2011, 10:24 AM

Quote:

Originally Posted by coyotearms

that's big time current!

Sure is! Anything that uses electricity itself as the source of heat energy is going to pull enormous amounts of current -- water heaters, space heaters, microwaves, etc. I'm guessing the Propex only uses electricity for its fan.

-- Geoff