Treva10-Inch Portable Fan, Powered by Battery and/or AC Adapter - Desk Fan Air Circulating with 2 Cooling Speeds for Personal and Travel Use (Black)

A power outage in the height of Texas summer is just about the worst thing that can happen. During one that lasted several hours, I ended up driving across town and taking my elderly dog shopping, just to get her inside somewhere that had a/c. More recently, we've had some short power outages, lasting maybe an hour each. Still, that's enough time for my apartment to go from slightly-warmer-than-I'd-like to my-living-room-is-a-burning-hell. Looking for a back-up plan, I decided to see if battery operated fans were even a thing, and that's when I found this O2Cool fan. I was a little nervous about buying it, since a few reviewers said theirs didn't work or didn't last, but a few reviews from hurricane areas had me wanting to give it a try. So I ordered one and crossed my fingers.TL;DR: Awesome fan, works great!First off, I like the size and design. This isn't one of those tiny palm-sized USB fans; it's about a foot wide in total, with a 10" span inside for the actual fan blades. It's slightly taller than it is wide, but it's depth is pretty compact. The vented cover is sized just right for me to not accidentally slip a finger inside when I pick it up, though it does have a carrying handle if you want to play it really safe. It does come with an A/C adapter, which I guess is nice, but I don't really need. Then again, it may come in handy if one of my two regular fans goes out and I need a temporary replacement.It's kind of a battery hog in that it needs 6 D-batteries to run, but honestly, I think that's a good thing. Any less, and it'd be a much smaller, weaker fan that wouldn't last any time at all. I haven't had occasion to run it for hours and hours and hours, but according to other customers, it lasts 9+ hours on high and even longer on low. I think that will be plenty to get me through the next power outage. And about those low and high speeds... This thing has great air flow. I wouldn't want to set it up 10 feet away from me, but since it's not tied to a cord or outlet, that won't be a problem. On low speed, there's plenty of air flow, and on high speed, it's awesome. It's slightly less powerful than the 22" corded turbo fans I use on a daily basis.All in all, I'd say this is an awesome buy. I was impressed enough with the first one that I immediately ordered a second, and both work very well with both the A/C adapter and batteries. I'm stocked up on D batteries now, too, so it looks like I'm set to ride out the next power outage in comfort!Update 12/1/2108: I bought two of these fans to get me through a power outage, which hasn't happened yet. But a few weeks ago, my apartment's a/c went out in the middle of the night, and the two fans I brought into the bedroom just weren't enough. I ended up grabbing one of these battery operated fans, intending to use the included A/C cord, and set it up on my nightstand. But in my sleepy, overheated stupor, I turned it on and quickly fell asleep -- forgetting to plug it in. Six hours later, I woke up and called maintenance, and they had my a/c fixed fast. Then I went to unplug and put away this fan, only to realize I'd left it running on high for 6 hours on nothing but battery power! So yes, I can now say without a doubt that these little fans run great for at least several hours.Update: Here I am. Power outage. Texas. Summer. While my neighbors sit in their doorways trying to catch a weak breeze, my dog and I are comfortably lounging on the sofa, a fan trained on each of us, while she sleeps and I read my Kindle. This is EXACTLY the scenario I wanted to be prepared for, and these fans are everything I'd hoped for!

I have been using this fan since December 2014 and it has been perfect. I originally bought this fan to use in my dorm because last semsester (fall 2014) the ac in my (low cost / old) dorm stopped blowing cool/cold air. It only blew out very hot air. I was left to the mercy of the university to send someone out to fix since we are not allowed to mess with at all. That person never came so rather than allow the hot air to blow and bake me to death, I just had to completely shut it off ( my dorm still uses individual ac units that are attached to the windows lol ) but doing so just leaves the air very stuffy and basically zero circulation in my room. That's why I bought this, sorry if it is too much but I feel it demonstrates what I was looking for in a fan when I went shopping on amazon for one.here are the pro's and conspros:Size is perfect for sitting on a desktop in the corner. I can set it in the corner and be able to utilize my desktop for either my laptop or for Home Work.To my amazement this little fan blows air very well. It has two settings for how hard it blows air. the lowest is usually enough for me since I have facing towards my face on my desktop but even on the highest I don't get that feeling of being smacked in the face by the air.It isn't "weak" but it isn't powerful like an industrial fan. If need a heavy duty fan then buy an industrial one. I obviously don't need such a large fan in my dorm and doubt it would even be allowed.Fairly quiet and sound isn't annoying. I find it soothing when my dorm room is completely silent.I use the adapter and don't really use the batteries because I leave it on almost all day 24/7. So I am able to tell you how long it lasts on batteries but it requires 4 D batteries so it should last a decent amount.Cons:nonewill keep review updated on status on my fan or if it ever "goes out".The price on this is very reasonable. I didn't want a complicated / high-tech fan that had tons of settings. I just wanted something simple but functional and durable. Looking at the reviews on amazon I decided this O2COOL fan W/adapter was just what I was looking for.

Love it and the way I can plug it up or use batteries for it. And it's working perfectly especially at night. I ordered two and might order two more. I just love them. Thank you for developing this.

I REALLY wanted to like this fan. It's a good size---unlike those "camping" fans, which are TOO SMALL---and it runs very quietly. I used it just a couple of times (I think I had it plugged in then), and stored it away in my bedroom for a few years. So, wanting to use it again for the hurricane season, I took it out and installed new batteries, but I find that it ONLY works when plugged in! Unfortunately, I need it for power outages, so will have to buy a new fan. I agree with other reviewers that the switch seems cheaply made, but I didn't care about that as long it worked---but it doesn't!---not on batteries. It ought to work---i did put the screws back in the battery compartment, and tightened them. Still nothing! If you need a fan to keep you alive during a power outage, you'll have to look elsewhere.Update: Encouraged by the fact that many others seem to have received a fully functional fan, I took a chance and ordered a new 10-inch Treva fan to replace the one I got in 2020. I installed new batteries (ordered fromAmazon) and tightened the screws. Yes! It runs, and on both speeds. Let's see if it lasts through the hurricane season. I'm giving it four stars provisionally. I bought this fanfor use during power outages, so it'sessential that it run on batteries.