Use figjam cooler directly on sleeping bag

[illera88]

Hi there,

I've been reading a lot of posts about the great figjam cooler in different sizes and shapes to cool an entire tent.

Since I just want to be cool inside my sleeping bag to sleep and I do not need to cool the entire tent, why can't I see more projects that focus on making a reduced space to cool down with the figjam?

What would be the best way to keep the sleeping bag cold instead of cooling the entire tent?

It is basically the reasoning behind the chillipad. So my next questions are: has anyone used the chillipad on the playa? Can a DIY version be built?

Thank you!

[FIGJAM]

You won't need the cooler at night, and you don't need to be in the sleeping bag during the day.

Just have the cooler blowing over you when napping during the day.

[illera88]

You haven’t answered any of my questions.

I will answer you nevertheless:
I know I don’t need the cooler at night, I may want to sleep in the sleeping bag during the day if it’s refrigerated.

Thank you for your cooler design

[Elorrum]

Inside a sleeping bag is designed to trap heat. Blowing wet air in there that wouldn’t evaporate as well would make a wet thing I think. Do you need the weighty enveloping sensation of a bag? A few suggestions: Ice packs maybe, or a recirculating cooling water tube arrangement like a draft beer jockey box to ameliorate the purpose and function of a sleeping bag. Lighter weight bag? A silk liner on its own is not too hot. At home, a small fan right at the edge of my bed blowing straight at me, blanket at my back, nothing between me and fan, helps with my own thermal regulatory hiccups in the night.

[illera88]

Thank you for your response Ellorum.

The cooling water tube arrangement is what Chillipad has:
"Temperature Regulation – The primary purpose of the Chilipad is to regulate the surface temperature of your mattress by circulating water through a network of microtubing. Sleepers can set the water to be as cool as 55 degrees, as hot as 115 degrees, or anything in between."

Chillipad woks as a mattress topper. I'm wondering if a similar thing can be built at home.

[FIGJAM]

The water could be chilled down to around 55 degrees by the bucket cooler, then some kind of pump to run it through the microhose.

[Token]

That’s actually an old desert brewing trick when you want to brew a lager in the middle of summer but your house is 80 degrees even with the AC on full blast.

Stick your fermenting jug into nice evap mat cozy, dunk it one of them party beer buckets filled with water and rig a small fountain pump to soak the evap mat.

Mid-50’s is about right with super low humidity.

So, Yes! You can indeed use a full size chill pad or any number of therapeutic “icing” gizmos to keep your chill-on for a nap.

It’s a neat project, I hope you do it and can come back with stories.

BTW, for the masses out there.

The reason for the sleeping bag is to provide an insulator from ambient heat so that the liquid cooling chillpad inside the bag can cool one human and ~ 90W or so of energy they shed.

So for 8 hours of Zzzzz - 720wh = 3600kJ

WARNING, if you removed 90W for reals, you’d freeze your ass

A Kg of ice (2.2Lb) at 0C melts when 333kJ are absorbed (Latent heat of phase change)

Getting that meted water to 25C ( nice and comfortable) specific heat of H2O is 4182 J/kg°C —> 4182 x 25 = ~ 105kJ

333 + 105 = 438kJ for ice to 25C

3600 / 438 = ~ 8Kg of ice to freeze you for 6 hours and thaw you out in the final 2.

Second WARNING: Heat capacity of ice is ~ 2000 J/kg°C and if the ice is really cold, like from a residential freezer at -20C, you could be in for a very cold nap.

TL;DR - you could use a cooler with a block of ice and some water in it to be real chill out there.

[Koumori]

Bring a top sheet/bed sheet. Stick vent of Figjam cooler underneath the top sheet. The sheet will inflate, enveloping your body with cool air that will allow you to sleep late or nap in the afternoon.

I lost an entire day when i figured this out. Was exhausted and slept for 12 hours.