The next project for the Magic Bus was to try to cool the thing off in this horrible Texas sun. I opted for a swamp cooler, or an evaporative cooler, or whatever you want to call it. It’s basically a machine that uses the thermal properties of water evaporating to generate cool air for a fan. It works really well in a place that is arid and dry. Which already means it’s not going to work very well here in the lone star state. No one from here ever says, “It’s a dry heat.” No, the saying is always, “It’s not the heat, it’s the humidity.” But during August it gets pretty dry. Around 30% humidity.
Swamp coolers were common, at one time, in Texas before air conditioners were affordable. My parents can remember having them. I can remember my grand parents having one. Then again, it’s hotter now, no matter what people say. The community where they used to live is no longer there, and is nothing but a bunch of dried up land. I’ve been there. I’ve seen where there USED to be a creek that they swam in. Any way… Here is how I built mine.
It ended up being a box made from plexiglass that was covered in foam board, for insulation. The box comes apart into two piece. The main piece is the part that holds the water. Which is why it was made from plexiglass and not wood. It’s basically a box with the top and the front half missing. I added some extra angled panels on the back side for the “swamp” section, and there is a lip part way around the inside of the box, but I’ll get to that.
On the back side, three holes were cut into the panels and covered with loofah sponges. That’s right, a loofah, or luffa. Both are acceptable. Originally they used swamp moss, which is where the name “swamp cooler” came from. Now days, it’s either aspen, cardboard, or synthetic fabric. I discovered that a loofah cut open works the same. It’s porous, it holds water, and it doesn’t turn to mush when it gets wet. They are hard to break down.
I used a small sub-pump to circulate the water and get the loofahs wet. That took some working. It was either squirting the water vigorously, or it was barely trickling down and getting anything wet. When I finally thought I got it, I realized it was pouring out the holes in the back. I finally got it though. That little pump works really well. It’s rated at a half of a watt.
The lip in the box has foam insulation on it. That is because the other part of the box sets on it. The other part is pretty much a whole other box that fits into the main one. The other box is the fan box, and that box has the lid built into it. The fan box has a tube added to it, so that when it’s all together, you can use the tube to fill the other box with water. The water box has a drain tube as well.
The fan I used is the Attwood four inch blower. This bad boy right here, and it is a bad boy. It moves a lot of air. It was the perfect fan for the job. It has one of those vortex type fan blades on it and it spins really fast. It had no problem sucking air through the loofah sponges. It says that it uses three amps, but I don’t know. It may be more. Twelve volts though, and if it is three amps, that’s thirty six watts, plus the half watt of the pump.
After I got everything working, I first tried it out at night. I ran the system for several hours. The air coming out of it was sixty two degrees. It felt very cold to the skin. The outside temperature was ninety one. Yes, ninety freaking one at night, but it’s not the heat, it’s the humidity, and that’s what I was getting. The van temperature was reading around seventy two, but it felt like it was about seventy eight, maybe eighty. Not too bad. It’s better than the temperature outside. I ran it for several more hours and it did wear down the battery, but not too bad. Down to right at twelve volts. Normal for the battery is about 12.5 volts.
The next day I made some adjustments and I put a wooden face plate on it. I hooked it back up, filled it with water, and tested it under the mighty Texas sun. By this time, the battery was technically charged. It was reading over twelve volts, but the solar charging unit never got it up to fourteen volts, which is needed to be “fully” charged. I ran the cooler all day long and the charger was never able to get it up to the needed fourteen volts. It was only partly sunny, but it could have peak charged the battery pretty easily without the unit running.
I was getting the same temperature as before, sixty two degrees. The air coming out was plenty cool. The outside temperature got up to ninety seven, and even hotter in the direct sun, which the van was in. Any other time, the van would become an oven and could easily get to the outside temperature, or even more. With the swamp cooler going, I was able to get it to about eighty five. Unfortunately, since it was humid, you could easily add at least five degrees to it. So it felt at least ninety. Not a temperature that you could live with. Not with the humidity.
Next, I added some ice to the unit. That dropped the air coming out of it down into the fifties, which dropped the temperature in the van down to eighty one degrees. Better, but still humid, not comfortable, and my battery was still never able to reach a peak charge.
So it ran and it ran, all day long, and kept the van, “cooler”. The sun set, and I let it continue to run for several more hours. I went out to check on it, and it will still about the same. The temperature in the van had dropped down into the seventies, but it didn’t feel like it. It felt humid and hot.
No matter how I opened the other windows up or closed them. It was stuffy, and it had also ran down my battery. When I checked the battery, it was below twelve volts. Way below. When I turned the unit off, the voltage did come back up closer to twelve, but it was still pretty low. There was plenty of juice left for emergencies, but it needed charging. There was no way around it. That was the straw that broke the camels back.
For it to work, I would need another battery to run the unit at night. Which would mean I would need some more solar panels to charge it during the day. That adds weight, which means more gas, which means more money. At that point, I might as well spend the money for an AC electrical hook up and use a real air conditioner. Which is what it all boils down to. My swamp cooler can only be used for a short period of time. Maybe during the heat of the day, at the most, on milder days.
Which means my choices for cooling the Magic Bus is either using a real air conditioner and an AC hook up. Or, to use it’s ability to move, and drive it up north where it’s not so damn hot. Next year, I am probably going to be choosing option “B”. As for now, I need to get to work on a way to heat the thing for winter. Which seems easier… and I have a plan.