Thanks Les. I hadn’t considered a battery powered fan, but after I checked, there are battery powered fans and USB powered fans. I happen to have a few power banks available from my solar panel experiment and this would be a good application. Even warm air can cool if it’s moving.

Russ... after the 2004/2005 season I was looking for a way to cool the bedroom down a little, without running a generator and portable A/C... I have an old frame home with jalousie and awning type windows, but inside temps were around 90F until after midnight... we started school back after the first 5 days of the 9 day outage, and it was tough to get up at 6AM with poor sleep...I retired in 2009 and worked on the problem.. the tent fan had been used in 2004, the idea to spin the ceiling fan came when a friend gave me a propeller adapter collet used on electric model planes...

I use the Ridgid fan on my gun cart (baby stroller with ATV gun mounts), along with a beach umbrella for matches during the hot months here in Florida

I found what looks like a pretty good fan that can be clipped to all kinds of objects for expediency. Internal li-ion battery can be recharged by USB while it’s running if your USB can push 2 amps. I’ve got a number of USB sources from wall plugs to power banks to that Goal Zero Yeti 400, afaik only the wall plugs push 2A.

While I was looking at USB fans I also found the AC Infinity USB Fan which I’m thinking might be useful for fabricating a USB powered swamp cooler. Just a thought.

yes. search for "camping fan" or "tent fan"

I received the Opolar 10000mAh 8-Inch ... Fan yesterday and tried it last light, running it on low, plugged in to charge the internal battery in the process. At a distance of about 7’ I could not hear the fan (on low) and could feel air movement — nice and easy to disregard. Neither the sound or air movement would interfere with sleep.

It’s running on battery now. At 3.5’ I can just hear the fan above ambient noise. I tilted it up so it blows just over my head — cool but not irritating. The clip shown acts as a stand if you have a flat surface to set it on. I haven’t needed to use the clip.

This was a great suggestion. Thanks Les.

This one runs on an internal battery that you have to charge. I realize your application seems to be non-emergency. But for emergency use, wouldn't you need something that runs on replaceable external batteries? The website says the fan has up to 20 hours of run time per charge (I assume that means running at the lowest setting, under ideal conditions). If we plan for a 3-day blackout, then that may not be enough unless you run a generator.

I'm thinking of getting a battery-operated fan for blackouts during the hot season. But there are so many out there that it's hard to decide which one suits my needs.

This will be fine for an emergency, SOCAL has pretty good sun. After I use the solar panels to recharge power banks and top off cell phones, there may still be some sun left.

my original tent fan that turns the ceiling fan runs 9 hours on single D cell... while I have two generators, my back up is a 7w Goal Zero panel, which can charge 4 AA Eneloops in about 3 1/2 hours of direct overhead Sun light... a two cell AA>D adapter will run the fan for about 6 hours... I've never run the Ridgid fan for more than 3 hours continuously at a match... I'll stand by my decision to power my portable hurricane lighting and radios to re chargeable AAs....

I'll repeat.. my two best lessons learned from Irma two years ago was to have a single power strip that could manage the multiple chargers, including those for AA, cell phone, and the contractor fan off a single wall outlet.. if I feed the house with the smaller generator, it feeds only 120v to select circuits

the second was to have a utility trailer and hitch on the John Deere mower to provide portability for the heavier generator so I could supply power to two neighbors plus myself on a rotating schedule... the use of a siphon fuel system allowed fuel to be taken directly from their containers

Whoah, I just learned of the existence of multiple AA to D adapters. Eneloops makes a 1 cell AA to D adapter, which seems to me to be a bit underpowered for an appliance that requires D batteries.

You electronics wizards out there, let me know if I'm on the wrong track:

AA and D batteries are all 1.5 V. A D battery produces 4.5 Ah. An AA battery produces 2-3 Ah. I assume the adapter wires the AA batteries in parallel. So that means an adapter with 2 AA batteries can produce 4-6 Ah, and an adapter with 3 AA batteries can produce 6-9 Ah. So why would they sell 3 cell AA to D adapters?

Because D cells are obsolete! They're expensive, sometimes not readily available and not very useful outside of a few applications. AA and AAA are very wide spread and inexpensive. The AA in a D adapter will work fine, it just won't last as long. But it's an Eneloop so presumably that's not a huge issue- just charge more often.