Electric Blanket Draw?

[FlyFish]

How many amps does an electric blanket draw thru the inverter in an 8-hr night? Would this sap the battery bank(3-29's)? thanks.

[wildtoad]

Is there label on the power cord or control box that shows the power usage? If not you might want to invest in a "kill a watt" device that will show volts/amps for any device you plug into it.

[Stogie]

Rule of thumb, if it generates heat it sucks amps. Check the label.

[62Morgan]

Agreed, electrical-resistance appliances have a huge power demand. Modern blankets pull less and are called "warming" as opposed to the former "heat" blankets.
The blanket label will have the wattage. Divide that number by the 120 voltage. You then have an amperage. You should know the amp/hrs for your battery discharge. This will give you a time interval. Unfortunately, you cannot place a timer here as they are regulated for light fixture amperage rates.

To save battery strength use a heavy weight quilt instead. Comfort comes at the initial laying-down into a confy (not cold) bed. Followed by a late night consistent level of warmth (usually reflected body heat will suffice). If the air temperature doesn't get too cold, you are good for the night. I apply the same idea as dressing for cold days: layer-upon-layer allow you to peel back as needed.

[vermilye]

Before you plan on using an electric blanket with an inverter, check that it will work at all. Many of the controllers don't like the output of modified sine wave inverters.

[hoppers4]

My electric blanket draws 60 watts per side. That would be .5 amp at 120VAC or about 6 amps at 12VDC. If you're running both sides of the blanket, double those figures.

[ralper]

My queen sized dual control mattress pad heater draws 70 watts total @ 120 volts. This is .583 Amps. Due to the electronic control it will not work on my modified sine wave inverter. Bear in mind that it will not draw this constantly and will go off and on with the thermostat.

[DAN L]

my queen size 12v mattress pad bed warmer from backwoods solar draws 5 amps per side during warm-up and less than half of that during the night. no need for an inverter. both sides are individually thermostatically controlled.
my battery bank has 300 ampere-hours available. of that we only want to use 150 ampere-hours to avoid deep cycling the batteries before recharging to make sure my expensive batteries last as long as possible.
we have been enjoying our warmer since 2007.
i see on their website that they only sell full size warmers now.
maybe you can call them?

Backwoods Solar Electric Systems

[ralper]

I forgot to mention that the inverter draws some power too. Add that in to your calculations.

[Ray,IN]

Here is a true boondocking electric blanket: David Butcher: PPPM Pedal Powered 12 Volt DC Electric Blanket
Seriously, A 12V electric mattress pad would be much more efficient since heat rises and no inverter is needed: MicroPlush Soft Top Low Voltage Heated Mattress Pad: CozyWinters

[HandyBob]

I figured out a couple of years ago that a small sine wave inverter with its own distribution system feeding receptacles for the TV, stereo, lap top, mattress warmer, the select comfort bed compressor and now the new cell phone booster that needs AC power is a great idea. We even use it to power the crock pot, because our big inverter draws 2.5 amps just keeping itself warm and that is just wasteful. This was not easy & not cheap, but a wonderful energy saver that takes great care of electronics. With the way solar panels prices have dropped this gets less and less attractive, but I would still do it again. I use a Morningstar Sure Sine 300 and it only draws about a half an amp at idle. The best thing about this is that it is totally silent, no fan. We only turn it off during extended cloudy conditions.

Our mattress pad draws about 3 amps per side, but it uses a timing control to adjust the temperature. I run my side on 3 or 4 (it goes to 10) and find that it only uses about 10 amp hours overnight. The wife hardly ever turns her side on. No comments about why that might be! I wish people would believe me when I say that reading the labels will not tell you this. You must measure any appliance if you want to know what it actually uses.

[FlyFish]

HandyBob - thanks, questions please. 1) Do I understand correctly that the primary purpose of Morningstar is to save about 2 amps/hr idle usage? 2) Are you saying the output of the Morningstar is better or more efficient than the big inverter therefore using less amps? 3) what mattress pad do you have? Your real usage rates were interesting. 4) did you do the inverter/distribution install yourself? I can't do that, how many hours of labor would I need to buy? (too many?) Thanks again, still searching for a way to keep DW warm, while boondocking occasionally to/from Alaska this summer. DW needs heat when temp drops below 100.

[HandyBob]

[QUOTE=FlyFish;802199]HandyBob 1) Do I understand correctly that the primary purpose of Morningstar is to save about 2 amps/hr idle usage?

Exactly. Big inverters are wasteful.

2) Are you saying the output of the Morningstar is better or more efficient than the big inverter therefore using less amps?

This is not the case when running big loads, but yes for small ones.

3) what mattress pad do you have? Your real usage rates were interesting.

The real point is that you have to measure anything if you want to know what it really takes. The labels show maximum draw, not actual. Then there is the duty cycle question. TV labels are usually way off, too. Read my RV Battery Charging Puzzle for more examples.

4) did you do the inverter/distribution install yourself?

Of course. I am a retired electrical guy. You'll understand more if you look at my web site. I started writing these things in order to educate the uninformed. I spent most of a day installing a small inverter and the wiring to four outlets in a big motor home last summer. That added up to over $600, but it did away with the need for another big solar panel. My mission is not to sell more solar panels, so I do things a lot differently than those other guys. You would have a very tough time finding a solar dealer who would do this. I just cringe every time I see an RV with the roof covered with solar panels. I will not talk to anybody like that any more. If they want to know how to fix it they can contact me. Most of those systems don't work and they are traveling advertisements for solar dealers who sell panels. I have four old panels on our roof, no generator and we run our life very comfortably. Dinner last night was cooked in the crock pot (on that small inverter), coffee this morning & toast were sun powered by the big inverter and the meter now says 85%. This is success!

[Peterd503]

We lived in a place with cold winters and no central heat. We got an electric mattress pad and would turn it on about 20-30 minutes before bed time. We would turn it off when we went to bed. That short warm up was all we needed for the night.