Welcome to my J.A.M. (Just Ask Mike) Session, a weekly column where I answer your basic electrical questions. If you’re a newbie who’s never plugged in a shore power cord (or ask – what’s a shore power cord?), or wonder why your daughter’s hair dryer keeps tripping the circuit breaker, this column is for you. Send your questions to Mike Sokol at mike (at) noshockzone.org with the subject line – JAM. Today I discuss 12-volt electric blankets and mattress pads suitable for use in RVs.
Dear Mike,
I’ve been reading that regular electric blankets shouldn’t be powered by an inverter in your RV. Something about the controller can overheat and catch on fire. Do you know anything about this? Is there a 12-volt DC electric blanket I can use instead of plugging one into the inverter? —Chilly Cathy
Dear Chilly Cathy,
First of all, it does appear that some electric blanket controllers can be damaged and possibly catch on fire if plugged into a MSW (Modified Sine Wave) inverter. That’s because instead of the less than 3% distortion of a PSW (Pure Sine Wave) inverter or inverter generator, many MSW inverters produce at least 40% distortion, and those harmonics tend to overheat things like motor windings and electronic controllers.
While you could get a small PSW inverter to power your electric blanket, the inverter losses could double the amount of battery power used by your blanket. So I think a 12-volt solution would be a better choice.
However, I couldn’t find a 12-volt DC electric blanket with a heating control or even one as large as a twin-size mattress.
Ad inserted by Google.
12-volt DC mattress pad to the rescue
However, after some research I was able to locate a twin-size mattress pad from Electrowarmth that’s powered by 12 volts DC from a standard “cigarette lighter” plug. And it has a 7-position control for heat settings.
Now, I think that a heated mattress pad under you is a far better use for electric heat rather than a electric blanket on top of you, since heated air rises.
I’ve asked for a test sample
Yes, I’ve contacted Electrowarmth for a test sample. As soon as one arrives I’ll try it out on my Jackery 1500 Portable Power Station for kWh usage, as well as put it on the bed in my Rockwood GeoPro trailer. I should be able to quickly determine just how much watt-hrs it requires from your RV house battery.
My wife has suggested I should try it out overnight in the RV during the cold weather, so I’ll put on my jammies and boondock in my back yard for the night. (No, she’s not sending me out to the doghouse.)
Ad inserted by Google.
If you can’t wait, then test it for yourself and let me know…
In the meantime, if you would like to try one for yourself, HERE is where you can get one for yourself on Amazon.
If you already have one or get one in advance of my testing, please let me know what you think in the comments below. This could be a very cozy and efficient way to sleep in an RV in cold weather without running out of battery power in the middle of the night.
OK, everyone. Remember that electricity is a useful and powerful force, so we all need to pay attention to safety precautions while using it.
Let’s play safe out there….
Send your questions to me at my new RVelectricity forum here.
Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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Hi Mike:
I am so glad you are going to research and test this product. I too have been searching for a 12v mattress pad or blanket, and would really like a double size one [hubby wants his side warmed up also] if anyone makes them. I found a twin size only bed pad for $86 here: https://electricblanket.net/p-34-electrowarmth-rv-or-truck-heated-bed-warmer.aspx
We have a double size electric blanket that converts the 110 to 12v so the electricity running next to your body is 12v. We use it when we have hookups and we use it to get the bed warmed up then usually turn it off for safety when we get in bed.
I used to use an electric blanket years ago but found out that an electric mattress pad is so much better because the heat is under you and much more efficient that way. Also, because the mattress pad is under the sheets it may only need to be laundered once in a while.
They are also available in 120 volt with a low voltage feature so smaller wires in the heater areas and less power draw. I use one at home and also in the 5th wheel.
I purchased an Electrowarmth heated mattress pad at the I80 truck stop on a winter trip a few years ago. The furnace in my Northern Lite truck camper worked fine but the temperature swings between cycles were uncomfortable when it was below freezing. I was able to turn the furnace down yet stay stay comfortably warm at a constant temperature with the Electrowarmth. My question would be about the safety of the product. I have had my pad for a few years. Do the heating wires deteriorate after several heating cycles? 12 volt wires shorting can start fires too.
That’s something I can research…
Just a thought…my brother, a fireman, said many house fires were caused by electric blankets. He said to replace them every five years. Perhaps the same applies.
Not sure, but I do know you don’t want to put them in a washer and dryer. And if they show any signs of wear they should be replaced immediately.
Check out the 18v Mikita electric blanket. Mikita makes some good tools. $109.
Besidesthe RV, I have lived 40 years in an off-grid solar home and likewise use energy efficient items like 12 volt matress warmers. In fact I sold them in my business when only one bramd was available. One problem is the warmer wires are connected to the 12 volt input wires inside the tgop edge, and they are crimp connectors,. They fail every few years and the connections are at fault. I learned to cut the top seam open, add a little slack wire length and solder the connections, sealing with heat shrink. That was the ONLY failure but regular, so we have kept them working nearly 20 years. Yes, I use a wall switch or unplug to disconnect the warmers when not occupied.
I can echo Kenneth Fuller. My wife has used one in the RV for years, including those years before we retired when we were heading from Alberta to Arizona in December and returning in January. Good excuse for me to snuggle over to her side on those cold nights too! Power draw has not been noticable, so I’m interested in seeing the results of your tests. Be aware that there’s no thermostat on these, so you’ll need to experiment with the setting. Wife usually leaves hers on 2, plugs it in for about a half hour before bed and unplugs it after 2 or 3 hours. I’ve written to the company and suggested a thermostat be incorporated, but maybe you could suggest how to build an add on using a snap switch or something?
Electrowarmth heated mattress pads work awesome. Truckers have used them for years. We like them better then an electric blanket because the mattress is warmed up. We have used them in a overhead bunk in our Lance truck camper for years. Very minimal draw on the coach battery over night. In fact it saves our coach battery a lot because we can keep the thermostat lower avoiding the constant use of the power/fuel thristy furnace.
Thanks for your input. Now I need to build a 12-volt plug breakout cable with a meter so I can monitor how much current, amp-hrs and kWh of energy is used by these 12-volt DC appliances. Much to do…
Mike, do be careful as we need your expertise for future years. I read the 1 star reviews on Amazon regarding this product. No way would I try to sleep with one of them. Apparently, the cigarette lighter plug gets so hot it actually burns fingers, sheets & mattresses. Do be cautious.
Don’t worry, I test everything. I suspect that the 12-volt plugs overheating are due to corrosion of the contacts in the female outlet. But that’s something I can actually test for since I have a FLIR infrared camera.
An FLIR infrared camera? I’m jealous. I guess I should check the 12 volt socket in my camper to make sure it’s not rusted. I promise not to stick anything in it until all power is OFF. Flashlight & a toothbrush (wire)?
I also have a medical grade borescope that’s tiny enough to thread into your arteries. It can see the contacts inside of a power receptacle without taking anything apart. I really want a stereo microscope for no particular reason other than I can get a better view of tiny electrical devices. I used one back in the ’80s when building missile guidance systems….
I never liked those 12V cigarette lighter outlets/plugs. I wonder if converting one to a two prong outlet of a different configuration than our standard 120V type would be better.
Yes as a former truck driver I can attest to these types of warmers. The catch is I have never seen one bigger than a super twin size. You might pick up a trucking magazine and look through the ads.