Running the O2 Cool on solar

This guest post is by Michael C and entry in our non-fiction writing contest .

Recently someone wrote about the O2 Cool battery operated fan. I liked the size of the fan (10 inch) and the battery operation. I was impressed enough with the review (on MD’s web site) that I went through the (MD’s) bookmark and looked at a couple of versions at Amazon. I noticed (and remembered from the review) that fan came with an AC adapter which convinced me to buy one. The AC adapter was not as useful to the reviewer as the D batteries and the adapter did not interest me much either. The jack on the side of the fan was another matter – it meant that I could power this fan with “external” power sources.

The power input for this fan is 12 volts, I can connect a 12 volt car battery to this fan or a small solar panel. The note next to the jack shows “500 ma” which is half an amp and the icon shows a negative ground. That negative ground is the shiny outside of the “N” style connector that plugs into the jack. I had recently bought a 10 Watt solar panel at Amazon for $70 (USD) that would work for the (0.5A x 12V=) 6 Watt fan.


The prototype is shown in the picture being tested during partial (notice the lack of shadows) cloudy skies. By prototype I mean that I need to put a longer cord on the panel so that the fan can be in the shade (with me) while the solar panel is in the sun. The 10 Watt panel gives me some extra power for the fan during cloudy weather, it seems to really rev up during sunny weather. In a “grid down” scenario this simple setup can work – with no batteries, the solar panel will last for decades to power other items too.

Of course, a small sized RV/Marine battery could be added to the setup to store the extra power that the fan cannot use. If the fan is on “Low” then the fan uses less than half the power that “High” takes. The solar panel will be facing the sun all day while you may have the fan off. In this case a battery will “take up” the extra power from the solar panel. A simple diode, to protect against panel damage and battery discharge, for a 10 Watt panel is 2 amp at 25 volt. A charge controller is not needed for a simple setup with a small solar panel. The battery may even need additional charging, from a car battery charger, if the fan is run constantly.

One last note – the fan can be powered by DC power adapters if you do not have the AC power supply handy. The DC adapters usually come with different “plugs” and have different selectable voltages. Using 9 or 12 volts will move the fan fast, 4.5 to 7 volts the fan moves slower. The fan runs slower and quiet, just a breeze. Just using the selectable voltage as a speed adjustment and it works with high and low fan speeds.

This contest will end on October 10 2012 – prizes include:

  • First Place : $100 Cash.
  • Second Place : $50 Cash.
  • Third Place : $25 Cash.

Contest ends on October 10 2012.

About M.D. Creekmore

M.D. Creekmore is the owner and editor of He is the author of four prepper related books and is regarded as one of the nations top survival and emergency preparedness experts. Read more about him here.


  1. riverrider says:

    also the harbor freight solar set comes with a “charge controller” that is marginal at best for its intended purpose but it makes a great charging station. it also comes with a multi voltage adapter plug that can be used with the o2 cool fan. add up the number of batteries, multiply by 1.5 to get the proper operating voltage of your size fan. running on higher voltage than normal will eventually burn out the motor. great post!

    • Hey Riverrider, I have been stuck for a year not hooking up my HF panels because I want to run 2 kits off one controller, but I’m not sure if I can; and don’t know if I need a fuse, or where to put the fuse; and I don’t know how to put it all in a panel box (I got a small one with a couple bus bars). Like, do I mount the bus bar on wood inside the panel box, or what; do I need to ground anything, and if this whole rig is nowhere near any plumbing what can I ground it to, do I need to run a wire to the ground? ETC. The panels are in the window. All I need is a little pep talk I guess. Halp!

      • michael c says:

        Penny Pincher,
        You can hook both sets of panels if the combined Amps are less then the Amp rating on the controller. If they are about the same then get another controller. The controller will cutoff everything it can’t handle, if your panels put out 12 amps and you have a 10 amp controller – you lose 2 amps. In Florida sun solar panels put out more than their rating sticker.

        I use a fuse on my “hand cart” solar system and I put it on the positive side so my setup is compatible with car DC setups. The fuse should go in the box you want to use. The positive buss bar should be “insulated” and the negative can be attached to the box. I would try to use a plastic like bakelite which resists burning and rotting. An old AC plug socket is made out of bakelite, can be cut and screwed to the box. Mount your buss on top.

        I don’t use a ground with any “moveable” setups. If your panels are in the window then you can move them. I do ground solar panels on the roof (exposed to lightning) with a ground rod.

      • riverrider says:

        penny, michael hit on it. you can hook as many as you want together depending on the controller you use. i would ground them to a rod in the ground or attache a ground wire to the one for your electric service. my setup is fused on the output side after the batteries, before the inverter.

        • michael c and riverrider
          Thanks for the laymans tips makes it easier for the less electricaly inclined.
          Good to see the Pack working together.

  2. TexasScout says:

    I have used this fan for a week at Boy Scout Summer Camp (hense TexasScout) for the last 20 or more years. A small car battery and a 10 watt solar panel will run it indefinitely. One of the projects I’m working on is a “swamp cooler” based on this fan and a milk crate.

  3. Thanks for the great tips. Living near San Antonio, we could use a little cool breeze every now and then…. Lol. We will need to get a few of them for our retreat.

  4. Tactical G-Ma says:

    Michael C.,
    Kudos for being so abservant and understanding basic electricity and electronics. “Necessity is the mother of invention”.

    That way of thinking is what will pull our keesters out of the fire when TSHTF. Bravo.

  5. MountainSurvivor says:

    I’ll keep that in mind.

  6. Thanks, this may make this fan what I’m looking for in my travel trailer.

    • SurvivorDan says:

      JP: Got this fan because of an earlier article here. I love it! I am getting too old to swelter at camp or during a power failure. The ex was jealous and got her own. I believe I purchased it at Walmart. I used it for many hours one day and the batteries held up. Will try to use my portable solar panel with it next time.

      • SurvivorDan says:

        I think the earlier article was by Riverrider. Hope I thanked him for the tip. Here in the desert it could make the difference between absolute misery and reasonable comfort.
        Nice reminder Michael C.

  7. Great information. I was looking at one of our O2’s the other morning and wondering what it would take to a. build in a solar recharger or b. add panels as you describe.
    Not being electrical minded I had no clue. Your article answers the questions But I would need a drawing or schematic to put it together.

  8. j.r. guerra in s. tx. says:

    Cool information, down here, any breeze in the summertime is a Godsend. But I do wonder if the motors for these units can take long run times, any signs of motor burnout ?

    • riverrider says:

      jr, i left mine on in a store room accidentally for at least a couple of days. still running.

  9. j.r. guerra in s. tx. says:

    Thanks Riverrider for that reply, I need to give these O2 fans a look then. Certainly priced right. I remember back during Hurricane Dolly, we just happened to be out on vacation when it came through south Texas. The neighbors were out of power for 4 days. They said it was miserable without juice, especially sleeping at night with high humidity.

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