The fan pump is a sustainable product where technology meets the costumers needs in hard situations. I introduced a simple method of keeping your head fresh when you are blowing your boat or air mattress on a festival, where it’s very hot and sweaty. The two fans are blowing fresh air when they are powered by a solar panel. I invented it for a school assignment on product design (at Howest Industrial Design Centre) for creativity.
The goal was to translate a (used) corrugated cardboard box to a product. You have to combine technology with the cardboard to generate a concept which is linked to the original function of the box.
In this instructable you can see how I prototyped a version of it using cheap materials and connections, it is not for real use. I’ll explain how you can make a perfect working prototype for people who have more time and money.
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Step 1: What Do You Need?
What do you need?
· The packaging box of a handpump
· 2x 12V DC Fan which is rated at 0.070 Amps (0.84 Watts): with brushless contacts and high quality bearings, it is rated to last at least 50,000 hours (almost 6 years of continuous use) without overheating. It can also push through a lot of air while drawing a very low current making it optimal for use with a PV solar powered system.
· Voltage regulator: when fully charged a lead acid battery will reach over 13.5V, and while charging can reach well over 14 Volts. If a 12V fan is powered with more than 12 Volts, then it will spin faster, get hotter, use more power, and fail much faster. Therefore, it is recommended that an LM2940 12V regulator is used. This gives a fixed 12.0V output from input voltages in excess of 12.5V (virtually flat battery), and up to 0.5V less than the input voltage if it is less than 12.5V.
· The solar panel: The Solar Panel should be chosen to match the power consumption of the fan. Two fans rated at 0.070 Amps uses 24 x 0.070 = 1.68 Amp Hours (Ah) of electricity per day. Therefore, the solar panel must put at least 1.68 Ah into the battery every day, plus an extra 20% to cover losses. 1.68 x 130% = 2 Ah. Obviously a solar panel does not generate its rated power 24 hours per day. Once you take into account nighttime, bad weather, and early mornings and evenings when the sun is low in the sky, there are not many hours of good generating time in the winter when this system is most important. For the UK you can expect an average of the equivalent of around 4 hours at the rated power per day in the spring and autumn, but in the winter this average can fall to less than 2 hours per day. So we choose a solar panel of 20 Watts.
· The battery: If a very small battery is used, a solar charge controller will be necessary to prevent overcharging of the battery. In addition, there will be insufficient stored charge to cope with multiple overcast days. It is best to match the battery with the solar panel to ensure that there is enough stored charge capacity for the fan to be powered even if it is cloudy for a week. With a 10 Watt solar panel and a 0.84 Watt fan, something of the order of at least 15-20Ah would be perfect, and except in the summer months (when this frost preventing heatsink system is not going to be needed) a solar charge controller would not be necessary since overcharging would not be an issue with the battery constantly being slowly drained by the fan.
· Some plates and connection materials as screws, bolts and nuts.
Step 2: Connect the Fans to the Box
Connect the fans to the box.
For supporting the connection I cut a piece out of a PU plate, that will be enough to hold the forces. Bear the holes for the screws and connect them with a bolt and a nut. 8 pieces of each would be enough.
Step 3: Putting the System Togheter
Putting the things together:
The final components of the system are a suitable fuse holder and fuse (use a 2 Amp fuse for a 0.84W fan to protect against short circuits etc), and a switch so that you can manually switch off the system if the battery is flat to give it a chance to recharge.
The fuse should be positioned as close as possible to the positive terminal of the battery to make it most effective. The on/off switch should be positioned between the battery and the voltage regulator(rather than between the regulator and the fan) so that no power is wasted when the system is switched off as voltage regulators use a little power even when there is no load connected to them.