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Old 11-16-2015, 05:23 AM   #31
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Re: Electrowarmth 12 volt mattress heater

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Originally Posted by daveb

Even engineers might argue over this one. Overall the way I feel is being it seems silly to invert DC to AC (factoring in the inverters losses) for a simple blanket when you can pay a little more for a DC model is why wouldn't you? I guess if the DC models preform poorly might be a reason.
Excellent points DaveB! It seems the DC bunk-sized warmers are fine in their application but the size mattress they're intended for---and no optional other/larger sizes---is what began this drifting topic.

Within the big truck industry there is a move towards diesel powered APU's that not only provide electrical power, both 120 VAC & 12 VDC air conditioning and heating of the cab/sleeper are available too. Because most bunks are of the twin mattress size so far 12 VDC warmers are the only offering. When/if this aspect ever changes we might see more sizes of DC bunk warmers but for now we're left discussing the merits of inverting.

Interesting discussion so far I think.
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Old 11-17-2015, 07:18 AM   #32
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Re: Electrowarmth 12 volt mattress heater

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Originally Posted by E350
And BTW, screw the microprocessor controlled new style electric blanket controllers and go with a simple rheostat DC controller. Because if it weren't for a lifetime warranty from a company that cares, Lands' End, my home use ~$250 120v AC electric blanket would be worthless.
Well if you are looking to limit your power usage then you would not want a rheostat. When you reduce the output of the blanket, that power is consumed by the rheostat. The microprocessor unit will most likely implement some form of PWM to control the output. We will essentially be turning the it on and off in rapid succession, the duty cycle (time on versus time off) will determine output. So if we wanted it set low, we would be consuming far less power.

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Originally Posted by E350
Since we're drifting away from the OP anyway I'd be curious from an electronics POV why a MSW source would fry microprocessors. With today's glut of these types devices its something we all need to know more about.
So I suspect in most cases it not the microprocessors itself but the supporting logic, not that it matters.
DaveB was pretty much on track when he brought up Harmonics. Noise is something we worry about in every electronic design, you can specialize and be a signal integrity. There are all sorts of rules, and design guides to minimize or reduce noise. In all those cases you would expect to start out with a clean power source.



There is the difference in a MSW and PSW. The PSW is similar to what comes out of your wall. In reality the MSW is a modified Square Wave.

The first thing that you might not see work on device would be a timer or clock, since the sine wave was at 60 Hz it was relatively easy to track the zero crossover point for a timer. Using a MSW as you input would throw that off, a clock on your microwave would be a good example if you left it in running on your inverter.

The other main thing is power, I guess I would liken the power output of the MSW to running your tools off of 200 ft of 16 gauge extension cords, sure it may run, does not mean it is running good or that you are not putting extra stress on it. A simple test would be to make a bag of microwave popcorn in your microwave. Use the same time settings running through shorepower and a MSW. I expect that you will see a difference in how much of the popcorn actually pops using the MSW.

Typically MSW will boast of a higher efficiency factor in their power conversion. But that is just stating cost of the conversion, and doesn't take into the actual reduced about. You may have a MSW that boast of 90% efficiency, but when compared to the PSW that is listed at 85% it still uses more power overall.

I expect that many things that were listed as not working on MSW now work only because of the better design in the power brick.

I have had a MSW for 11 + years, and only have one device that didn't work for me. (But I really don't run much on the inverter). I am currently switching to a Pure sine wave unit, but I would say that decision was weighed more with the built in charger section than the inverter part.


-greg
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Old 01-04-2016, 01:43 PM   #33
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Had the chance to use my mattress warmer over the holiday. I was mostly staying at locations with power so no information on battery drain. As a warmer, it worked great. Nice getting into a warm bed. I did find that I slept with the controller set on 2. The temps were just at freezing.

I also purchased a small electric heater at Camping World for under $20. I used it to warm up the van and to make sure the tank did not freeze. I connected it to a remote plug so I could turn it on in the morning to warm things up without getting out of bed. It did a great job killing the chill. In extreme conditions with the lip down, I could see it working very well if you have power.

On top of these i had insulated pads for the front windows. They seemed to help.

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Old 01-04-2016, 04:34 PM   #34
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I picked one up after reading this thread - For someone without a furnace in their van like me this is a game changer! I had the dial set to 7 for an hour upon start up then slept with the dial at 3. Kept us cozy in about 20 degrees where I would otherwise wake up cold in the middle of the night. My only wish is that they came in full or queen size!
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Old 01-04-2016, 05:57 PM   #35
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I got one for the girlfriend. She is a BIG fan. And my van has a furnace.

I'm not at all worried about the energy, as if it's cold enough to use this, my fridge is either off or using very little energy, so this takes it's share...
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Old 09-23-2016, 02:17 PM   #36
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Thanks for the post. I'm looking at using one of these bunk warmers in a backcountry ski rig for single night use. From the posts it sounds like people are seeing 2-3 amps/hr roughly so maybe 15-40 Ah might be about the right usage.
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Old 12-02-2016, 12:59 AM   #37
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I found the Electrowarmth 12 Volt on Amazon for under 100.00 that is a great way for me to go until I figure out a permanent heater. From the sounds of it though when I am solo I think I am good with my wool blanket and sleeping bag, I camp in my tent in 0 degree weather so the van is going to be warmer than that. Since the pad is smaller than the bed I can put it on my wifes side and she will be happy. From the sound of it this may be the permanent option.
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Old 08-30-2018, 10:43 AM   #38
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Difficult following this thread but TexGT you were referring to Electrowarmth mattress pad heater?
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