portable boot dryer

My pennys worth.I expect my boots to get wet & as someone put it,suck it up & put your wet clothing including boots on in the morning.Some trampers go to a lot of trouble to keep their boots dry-good luck with that.Rock hopping creeks often turns to tears so just get wet & carry on.When I get home,wet boots stay in the shed for several days while I use a dry pair.Seems to work for me.

Thanks for the advice @lewshaw I'm just unsure how it helps me design my product? I expect my boots to get wet and i don't rock hop, that's exactly why I'm making this. Unfortunately my shed doesn't move around with me and doesn't dry my boots like yours. Thanks 😊

I can't think of many (ok, any) times when I've got wet boots on day 1 and then expected them to stay dry the following days... so no way would I carry either a battery operated or chemical device to dry my boots out overnight :-)

There could be an international market, or maybe a market amongst some other demographic of trampers or walkers in NZ, but perhaps this isn't the best place to ask.

trenchfoot is an issue if your feet are wet 24 x7 like the military when they are in the field and cant take their boots off regularly, trampers can easily dry their feet out once they've stopped walking for the day

The product seems to already exist: [Therm-ic Refresher V2 12V](https://www.snowinn.com/ski-store/therm-ic-refresher-v2-12v/137862583/p?utm_source=google_products&utm_medium=merchant&id_producte=11985346&country=nz&gclid=EAIaIQobChMI2eKq3pnw8AIVcJVLBR0XxQonEAQYASABEgJ28vD_BwE&gclsrc=aw.ds) https://www.snowinn.com/f/13786/137862583_7/therm-ic-refresher-v2-12v.jpg

@Ian_H are you taking that hiking? Because the thermic designs aren't that portable. By the way, the cars charging that, and you can't bring your car everywhere you go. But there's nothing to stop me taking specs off this design refining them and using them on mine. Cheers

I haven't got one, I'm just looking at pictures on the inter webs. I'm assuming it has a rechargeable Li Battery of some sort inside, and a fan and heating element and a little bit of electronics. I'm guessing you'll need the same. I'm not convinced you'll be able to refine the design or something similar in a way that makes it significantly smaller, lighter, more portable. The limitation is the amount of energy you need to evaporate water in the environment you're going to use it in. It seems to me that the energy requirement is quite large, and so you need quite a big Li battery to even do one cycle of boot drying in the environment you'll be using it in. Thats the main thing you need to establish before you go any further, what's the ballpark energy Watt-hours or kJ needed in the typical temp and humidity you'll be using it in. What size of battery does that then dictate, and is that practical to carry? I'd be curious if you do have/get any actual numbers for watts and hours needed to remove say 200 ml of water per boot along with ambient temp and humidity values as they're going to have a big effect on the drying. My guess is you'll get at most one cycle of boot drying off a full charge of quite a big battery, so it only makes sense for people who are living in or returning to a vehicle or a building where they have a way to replenish the battery after every use. If you've got a source of replenishable electrical energy and a separate source of heat (woodburner or a car heater blowing warm air into the footwell), then maybe such a device helps get your boots dry and makes some sense.

Hooray,at last some common sense as usual from Ian. Well done.

OK, dusting off the thermodynamics and trying to put some numbers to the (hopefully) common sense: Evaporating water at 15 Celsius takes 2460 J per gram. If you need to evaporate 400 g of water from a pair of boots, you need 984 000 J or 984 kJ. Dividing by 3600 to turn into kWh gives 0.273 kWh or 273 Watt hours. A 20 000 Ah Li battery pack weighs about 450 g, costs about $75 and can provide up to 72 Watt hours, so you need at least 4 of them to have any chance of getting your boots dry. The above is probably a bit optimistic, you also need some energy to run the fan as well, so you're looking at at least 2.5 kg and $400 worth of Li batteries just to get your boots dry once. A 12 volt 50 Ah deep cycle battery in a campervan or car weighs more than 20 kg but can provide up to 600 Watt hours, and recharges each time you drive, so drying your boots this way might make sense from a vehicle/hut with 12 V off grid power, but I can't see how you can get anything portable to do the job.