USB Heated Mattress Pad…hmmm

I dunno, even drawing 2 amps, that’s 10 watts total.  I’m not sure how much heat you could really get out of a larger pad.

You can find many models of USB-charged hand warmers on the market. The best, according to the Wirecutter, last about seven hours, and weigh 3.5 to 7 ounces. One of their favorites can even charge other devices, obviously reducing the warming time.

But that warms just one small area, for less than one night. I doubt a heated pad covering a much larger area with a similar energy source would add much heat.

At home, our Sunbeam Premium Quilted Heated Mattress Pad draws up to 360 watts. We can barely feel the heat when the dial is set to 4 out of 20. If the settings are linear, that’s 72 watts for a queen sized bed. Scaling down to a full-length sleeping pad, that might be 20 watts. Maybe if a USB-powered pad could draw from two or three batteries at the same time …

For about 7 ounces, you could distribute eight Hot Hands chemical hand warmers in pockets on a sheet, providing “up to 10 hours” of warmth – enough to get through one night. And a custom sheet could target your coldest spots, e.g. feet and hips. On my next trip, I might take a few Hot Hands to throw in the foot of my sleeping bag for the coldest nights.

— Rex

I found another listing for what appears to be the same product listing a current consumption of 2A at 5V, so 10W.

I just pulled a rechargeable AA NiMH out of a drawer and it says 1.2V, 2500mAh, so 3W for 1 hour.

So you’ll need about 3 AA batteries for every hour of heat. 6 hours of heat means 18 batteries.  Granted, that’s at full power, but it’s also a small pad, less than one square foot.

Have you tried putting a few chemical handwarmers in you bag at night?  I assume you’re already using an insulated, winter sleeping pad?

Yup…tried the Hand Warmers..and they work pretty well… Also the tried and true boiled water put into a Nelgene (lasts about 4 hours).  Just playing with ideas…  I carry a bomber battery so I just thought maybe I could make yet another use of it…

I have had a number of engineering students try to tackle this problem.  The bottom line is that insulation (down, pad, whatever) oz for oz is better than electrical heat.  Have you tried loading up on calories before going to bed?  My 2 cents.

You can get all sorts of USB heated clothing that would accomplish the same thing.

What temps are you having problems with?   What sleeping pad?   What sleeping bag?

You could always do the hot water bottle trick.  Heat water and put it in a nalgene (yes an old heavy nalgene), put inside a spare sock and put it in your sleeping bag.

I feel confident that we can get you a solution (other then a heated pad) that will let you go out in the winter.

Temps below 25 down to 0….And yup…use the Nalgene every time…

All somewhat works…I’ve just been thinking about this new new idea and wondered what was out there.  I’m enjoying reading the ideas on the thread.

I was going to say what about something like this?  https://www.amazon.com/Electric-Adjustable-Temperature-Portable-Washable/dp/B07MKGKDKD/ref=pd_lpo_vtph_200_tr_img_2?_encoding=UTF8&refRID=VF267PDT22AEP9HJSRJ6

Says works for 6 hours, could carry extra charging packs for extra nights.  Also the old boiling nalgene will stay warm most of the night.

I’m going to also add, I feel like pads suck.  I’ve yet to lay on one that is comfortable for more than a few minutes.  Feels like they cut off circulation and then everything gets cold.   Ever try a hammock?

rather than trying to bring more electronics in to your backcountry ” fun ” …

why not try an old trick of one of our more famous mountaineers, Yvonne Chounard.

before bed eat a tablespoon of sugar (think candy bar) and a table spoon of olive oil.

this should stoke your internal furnace most of the night.

One thing I’ve thought of, but have never actually done: sew 2 pockets/pouches onto the back side of your thick top base layer, positioned over each kidney. At bedtime, place one of the larger body warmers into each pocket. They put out more heat than the smaller hand warmers, and they also last for 7-10 hours. What this technique should do is to warm the blood passing constantly through your kidneys, which will then reach every cell in your body. It should help greatly to keep you warm. Only my theory, of course.

Like I mentioned, I’ve never actually done this, but I always figured that it would work. The last time I slept in < 0* F I simply tossed one of these body warmers into the foot of my -40* F down bag. I was wearing significant clothing as well (Cap 3 top and bottom, plus 100 wt fleece over those, and a warm hat). At 3 AM I was so warm that I had to remove the body warmer from the foot of the bag. I also used 2 thick pads to sleep on.

I also time my evening meal so that I will hit the sack right after I eat. This helps me stay a lot warmer while I sleep.

Edit: My pal recently developed Reynaud’s syndrome, and he found a pair of cheap liner gloves that have a similar pouch on the back of the wrists where he can insert a regular hand warmer. That’s where the hands’ blood vessels are located, and this trick keeps his hands from going numb while we snowshoe. Toe warmers do the same thing for his feet.

A USB device, even at a full 2 amps isn’t going to be more than 10 watts of heat.   A single liter water bottle, heated to 170F and cooled to 90F over 4 hours averages 10 watts of heat. Your basal metabolism is 80-100 watts.

To a big fraction of your metabolism, you’d need lots of hot water bottles or multiple USB-powered devices.

A hot water bottle does work to get the sleeping bag and your hands and feet warm again.

More insulation (pad, quilt or clothing) weighs less than the batteries, can be used night after night and can’t drain flat.

How about a down suit? At four pounds probably less than the necessary batteries and electronics. Maybe more expensive.

http://featheredfriends.com/expedition-down-suit.html

I’m reminded of the “Where’s the suffering?” thread.

I’m also grateful for peri-menopause. The colder it gets the better I sleep.

I think the best thing for warmth are two sleeping bags and a tent mate to cuddle up closer to.

get a sleeping bag rated -20F or something

or get a really warm quilt that will go over your current sleeping bag

and warmer pad

at some point you will be warm

balaclava over your head might be good.  wear extra clothes like insulated jacket, although there has to be enough room inside your sleeping bag for it to loft.  maybe get a sleeping bag that’s bigger around.