So going on a Boy Scout 10 day long camping trip again this year! It was a blast teaching eager young boys about how to survive and showing them off-beat ways to do it!

So I'm not like a lot of the other guys who take the nice AC room at night! I enjoy spending time with the boys! So like them, I sleep in a tent. Might be three in their tent but only one in mine!

Anyway, two years ago I had an old D battery fan that was $hit had to hit it every night to make it work. It was God who sent 9 out of 10 nights.

Yet D batteries are heavy to carry around! If they can be solar recharge I'm sure there is something better!

I have a 28-watt solar panel ( Yes I'm thing of getting the newer one.) I want something that I can charge the batteries with the solar panel. Why because I'm going to use this in more remote places also that will not allow me to charge some 20v,40v, or 80v battery.

I know pretty much we are car camping but wanting to keep this real for myself! Also don't want to spend money on something I'll just find out is junk when I need it most.

Last post most suggestions are heavy large 20v+ battery-powered fans! Yet never got an answer can they be charged solar?

So part of this is one other thing. Will one battery last more than a max of 12 hr? Next will that battery charger in or less than 12 hours?

I know a lot of what-ifs! Me I'm looking for something that will last 12 hr +(not that I sleep that.) Yet can be charged by solar. Don't care if I need to buy multiple batteries.

So looking for advice!

How about a USB plug fan like this:
Fan

With a power bank:

Bank

And a panel:

Panel

Might have to run the number to see about how long fan will run from a full charged bank and how long to recharge bank with panel

My gal and I have four O2 Cool 10” D fans that come with an AC adapter. Older versions were 12vdc (8 Ds) and the newer ones are 9vdc (6 Ds) and are two speed.

A set of Ds can last upwards of 50 hours.

The new name is something like Travia.

Target and WalMart sell them.

Chris

Back in 2019 you and I exchanged several emails about how to build a battery pack that could be charged with solar.    Did you ever pursue that project?   I am guessing that you didn't.   Because I am thinking that if you did then you wouldn't be here now asking people whether or not different batteries can be recharged with solar and used to power a fan.  

The panel that you described back then was the BigBlue 5V 28W Solar Charger, which is designed for cell phones.    Is that the panel that you are planning on using on this project?   It will add some challenges if it is.   One thing that I recall was that a number of people reported that the best that they could get was 14 watts from it.   For the purpose of this conversation I am going to go with that number.    But you might get less.   Keep in mind that during that recent freeze in Texas, there were a number of people that intended on using solar for backup power and they only got 10% of the power from their panels that their panels were rated for.   So even 50% capacity might be over estimating.  

Looking at the old O2 cool fan, it is a 12 volt fan that runs at 6 watts.    So for every hour that you run it, you will need to recharge it for thirty minutes in full sun with the BigBlue panel described above.   That means that it will require direct sunlight aimed directly at the panel for six hours to replenish the power used in a twelve hour night.   But would I use a 5 volt panel to recharge a 12 volt battery?   No.   I would not.   I would get a 12 volt panel.   It simplifies a lot.  

But you haven't given us much of any information to help you make a decision.   We don't know your budget.   We don't know how much space you have to work with.   We don't know how much weight you are willing to carry.   We don't know if you are willing/able to purchase what you need to make an idea work.   We don't know how much air will you need to be comfortable.   You haven't indicated if a noisy fan would bother you.    

FYI:  I have a couple of the older 12 volt O2 Cool fans.   They are noisy.   One thing that I like about them is that if you know anything about electricity it is very easy to cobble together a different power source for the older O2 Cool fans.   I have run them from AGM batteries, car batteries, solar panels, and computer power supplies.    And they don't move a ton of air.   You might have to put it within a foot of your head to make a difference.  

You complain of alkaline D batteries being heavy.   But the energy density of alkaline batteries are pretty good.    The worst alkaline batteries have a higher energy density than the best NIMH or NiCd batteries.   So by the time that you pack a solar panel, charge controller, decent sized AGM battery, and the other items that you will need you may be better off with a couple extra sets of alkaline batteries and an O2 Cool fan.   It isn't nearly as "cool" or high tech but a few cloudy days won't torpedo your plan either.    

Whatever you plan on doing, try it for a few days first.    There isn't anything worse than getting out in the field and realizing your equipment won't do what you thought.   Good luck.  

No never did build that battery bank mostly because I was working so much I never got the time and when the time past when I needed it I did not think I would need the bank anymore! How wrong I was! I had to learn that the knowledge that you have given me would have been useful not only for the camping trip but for when the power went out several times in my area! Should have went thought with your knowledge now I regret not doing it!

Since June is coming up fast you should probably figure out what you are going to do.  

A typical 100 watt solar panel weighs about 15 pounds and runs $100 on sale.    A typical 50Amp Hour AGM style battery (25 Amp Hours usable) weighs about 30 pounds and costs about $110.   A 12 volt automotive fan costs about $17.00 - $25.00 and weighs a couple of pounds.   So on a good day you are looking at 45 pounds of gear and $235.00 for a reliable solar solution for running a fan all night indefinitely.   And then you still have to figure out how to get the panel to the campsite without breaking it.  

Or you can buy an an O2 cool fan for $17.00 that weighs 2.5 pounds and a couple of sets of D Size batteries for $1.20 and 0.36 pounds each.  How many batteries are needed?   That is going to depend on the actual fan that you buy.   Some are more energy efficient than others.   I haven't used this fan but people that have say that you can run it for 3-4 nights on low with one set of Energizers.   So without trying the fan before hand then would recommend that you take three sets of batteries.  7 pounds and $21.60.   You could probably get by with two sets though.   Me?   I would buy four sets and leave two sets in the car.   Then if I needed them I could hike back and get them.    

Now this fan does have a cigarette lighter adapter available.   I have run a similar fan overnight from an automotive jump pack.   The irony is that they typical Jump pack has a 20-25 Amp Hour battery in it.   Which to protect the battery, you cannot draw more than 10-12 Amp Hours from it.    That is the same amount of Amp Hours (at 1/6 the weight (18 pounds vs 2 pounds) and 1/19 the cost ($133 vs $7) that you can expect to get from one set of D cell batteries which you can run dead.  

Or you could buy a 12 Volt AGM battery and equip it with a cigarette adapter.    But you are still dealing with the extra weight of Amp Hours that you cannot use without damaging the battery.   Remember that draining AGM's beyond 50% reduces their life significantly.   And I am thinking that LifePO4 batteries are out of your price range.  

So despite the fact that it isn't "cool" (no pun intended) the solutions that people are recommending OVER AND OVER is the most cost effective, weight efficient, reliable, and shortest learning curve method of using a fan to stay cool for short periods of time off the grid.  

Keep in mind that these are general numbers and you might be able to get these solutions done cheaper.   But they might be more expensive.  I used current Amazon prices for the specific parts that I looked up.  

So if I were you , I would get the fan and run it on D batteries for this year, and throughout next year play with different ways to power it.   Then when you go camping NEXT year you will have built up some experience on what works and what doesn't for wind/solar and whatnot.  

https://www.amazon.com/O2COOL-10-Inch-Portable-Desktop-Circulation/dp/B013BOC6VC/ref=sr_1_4?dchild=1&keywords=02+cool+fan&qid=1619955422&sr=8-4

As always YMMV.