Saturday, July 9, 2016

It's bloody hot in here!

They talk about the mercury hitting the nights. It's so hot my thermometer fainted! Inside the bus it's over 100F. In an astonishingly early start, I set the fans going at 10AM. They seem to be working because the back of the bus is as hot as the front. It seems my fans are drawing the hot air forward and the sun is heating the front faster than it can be cooled.

After sweltering a while, I put some of my latest electrical cable together. This cable is designed to allow me to connect a standard household cable to the bus. It's quite short but as I'm missing a household plug, that mini project is on pause.

Just then there was a horn repeatedly honking outside. It was the post lady in her little red jeep. She had brought me my solar panels. They're not as dark as I'd like but they'll do. They lack suitable mounting brackets but I think I can fix it up with some. The next thing will be to work out the wiring. As a test, I tried one with one of the CPU fans I'd removed from the back. The fan started with no problem whatsoever.
There seem to be two ways to go. I can either use the solar panels to charge a 12v lead acid battery and wire everything through. The other option is to keep running everything off D cells or even AA cells and to set the new panels to charge a bank of AA or D batteries. Quite frankly both options have pluses and minuses. The small battery solution is more flexible though more labor intensive. The big battery version is labor intensive for installation and the lead acid battery has its own unique problems.

As far as the solar panels go, I will not immediately install them. I need to consider locations first since they're light colored rather than dark as I'd hoped. I also need to consider using the 12v fans I have ordered. One of the major issues with a full 12v system is routing the cables, particularly over the fuel tank and battery compartment. A smaller system based on AA or D cells works around that problem. It also gives me the option of a backup from disposable batteries.

If the panels are used to charge small batteries then it should be possible to locate the battery charging tray fairly nearby in order to eliminate excessive wiring. There seems though to be a complete lack of charge controllers that can be used to charge single cell NiMh batteries.

At 7:30pm I turned the fans off, having turned them on at 10am. That's 9.5 hours on one set of batteries and 26.5 on the other set. It really is quite amazing that my ventilation unit has been running for over a day on a single set of batteries!

Looking online it seems alkaline D cells are about 19ah. Assuming the 160ma draw from a CPU fan, I should expect my D cells to render 118 hours of service. That's pretty much a week of service or even more if it's turned off at night. Given the low price of alkaline D cells, they're a very viable proposition, even without recharging.

There is no possible reason why I would ever need a generator. I still have to experiment with a water powered air cooler though. Yesterday I realized I probably don't need to go to the expense of aluminum tubing. I could probably work it just as well using Pex hosing. Indeed, given care, the water cooling system could just be put down beside the bus, filled and connected.

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