Solar Power Baby Steps: Room Fan!

I have been very inspired since reading and reviewing Prepper’s Total Grid Failure Handbook. Except for our stand-alone solar devices (we have a solar charger for our electric fence, a solar-powered attic fan, a solar barn light, a solar flash light, and a solar car battery recharger) I have virtually zero experience with generating solar energy. Most books and articles on the subject get way over my head too quickly, so that I have no clue as to how to apply the information. As a hands-on learner, I needed the simplest project I could manage in order to get an experiential grasp on the basics. After reading the Grid Failure Handbook, I began to see ways I could expand our use of solar electric power, especially in the area of preparedness. For example, it’s not uncommon for us to lose electricity during lightning storms, ice storms, or hurricane aftermath.

Most of us are familiar with rechargeable batteries. We recharge them by putting the batteries into a little holding device and plugging that into the wall. Then we pay the electric company to recharge the batteries for us. Solar powered devices may or may not have a battery (our attic fan, for example, only works when sunlight hits its PV panel), but the barn light, fence charger, and flashlight each contain their own small battery for after dark use. My new project was going to use the sun to charge a 12-volt car-type battery that I could use with the 12-volt device of my choice.

There are a lot of 12-volt appliances out there. Many common items are wired to run off of car batteries for RVs, boats, camping, tailgate parties, over-the-road truck hauling, etc. Any appliance you use at home probably has a 12-volt version out there. As a truck driver, Dan already has a small 12-volt oven (looks like an old-fashioned lunch box), clip-on fan, cooler, 1.5-quart slow cooker, and a DVD player. All of them use the same kind of electricity as the battery stores (DC or direct current) and simply plug into the vehicle’s cigarette lighter.

In choosing an appliance, I thought about our preparedness needs. I can cook and heat without electricity, wash clothes without it if I need to; even lighting isn’t the greatest need. If we lost power during summer, however, the thing we’d miss most is our fans. Since we’ve stopped using air conditioning, we use our fans a lot! They help keep us cool, but also, by circulating air in the house, they help prevent mildew and mold. Because of our humidity, that’s important! After searching around on the internet, I found a 12-volt room fan.

To attach it directly to the battery I got this eyelet terminal battery clamp with a 12-volt socket.

The battery is a deep cycle battery.

This is not the same kind of battery one typically puts in a car. In a vehicle, a starting (cranking) battery is used. It has to supply enough juice to get an engine started, i.e., rotate the crankshaft. It can bear a high load for a short duration. Something like my fan, however, doesn’t take much energy for start-up but must draw continually to keep running. A deep cycle battery can bear a light load for a long time, so it is better suited for these kinds of applications.

Another note about this battery is that it is a “maintenance free,” aka sealed battery. It has a shorter lifespan that the flooded cell batteries you have to add distilled water to, but also, there’s minimal off-gassing and no chance of spillage. For those reasons I felt it was the best choice for indoor use.

To monitor the battery, I got a small digital voltmeter.

When it gets to between 12.4 and 12.1, then I’ll know it’s time to recharge the battery. In general, frequent top-ups without letting the voltage get too low will increase the life of the battery.

The set-up is super simple.

The clamp and volt meter attach directly to the battery (red on red and black on black). The fan plugs into the cord’s 12-volt socket. I was actually impressed with the breeze the fan creates, even on low!

Since the amount of electricity being delivered (12 volts) is the same as is required to run the fan (12 volts) nothing more is required. If I want to power a typical household device (which uses alternating current or AC), then that’s another story (and another project). As long as I use 12-volt devices with this set-up, then I’m good to go.

So what about recharging the battery? This is where the car battery recharger comes in. We bought it not too long ago from Northern Tool: a 20-watt solar panel with a 12 Amp charge controller.

Now we’ll see how long my fan can run on the one battery, how often I need to recharge it, and how long that takes. I can see the need for a second battery for a quick switch when one needs recharging.

We’re still a long way from energy self-sufficiency, but in terms of preparedness it’s a good step. Next I’ll tackle something a bit more complicated.