Thursday, August 3, 2017

Fannying around today.

Lets face it's: 88F and 54% humidity inside my motorhome isn't very comfortable but it's better than the 104 it was a couple of weeks ago. As my extraction fan isn't doing the job I hoped it would, I'm continuing to work on circulation fans. As I write this blog (using an elderly tablet and a Bluetooth keyboard), I am cooled by my current desktop fan. It is one of the bunch of O2Cool fans I bought in Walmart a year or so ago when I first started experimenting with ventilation. In fact, it's the only one of the four that I didn't dismantle. One was used as an induction fan, sucking cool air in from under the bus. That didn't really work all that well. The other two were used as exhaust fans which were then replaced by more powerful CPU fans and then by my current bilge blower. Meanwhile the two O2Cool fans that were used as exhaust fans got recycled into a powered window unit.
Today I'm trying to complete tasks as yet not completed. The stifling heat is really not helping too much. Somebody needs to drag South Carolina a few hundred miles further North into an acceptable climate zone! So, the things I wanted to complete today:
  • Complete construction of my bedroom CPU circulation fan and install it.
  • Complete gluing the wire for the galley CPU fan.
  • Charge both of my 7AH batteries.
  • Turn the 5AH battery over to running the CPU fan (as it did before)
  • Work on turning the 50 cal ammunition box into a carrier for my two 7AH batteries, including twin voltmeters and twin USB charging connections. That will be my version of a power bank.
Speaking of power banks, I saw one in Batteries Plus a few days ago. I think it was something ridiculous like 20AH. Had I not already got my bits and pieces for my own portable power bank, I'd probably have bought that. My mission there was not however to buy big batteries. I just wanted a watch battery. When I picked myself up off the floor after I heard the price, it was 50/50 over whether to just buy another watch instead. I paid something like $6.50 for my watch in a sale in Walmart something like a year ago. The battery was $5. I'd looked at watches in Walmart and found the selection they had was not easy to read in low light without pressing the light button. As I need to check the time when I'm at the helm of a bus full of screaming children at 6:30am or way before dawn, that wouldn't have worked. Thus I paid my five pounds of flesh and got a battery. While I was there I did have a good look at the batteries. I must say I was impressed by the size and weight of the lithium bombs. Having said that, if I were to go to lithium batteries, I'd want them in a pod behind the back wheels that could be quickly jettisoned in case of explosion or fire.
I'd like to claim that construction of my second circulation fan assembly went easily but I still could not find my aluminum rivets and ended up accidentally using a steel rivet. My Harbor Freight long handled riveter of course, didn't want to work. Thus I had to use a hand riveter which was quite a challenge with a steel rivet. In the end I had to press the riveter closed with all my force and use the bus floor to support the other handle.

Having done that I noticed my extraction fan gave only 6 minutes of extraction today as opposed to 15 to 20 yesterday. I suspect that is rather more to do with the overcast day than with a global plot against my solar setup though I cannot rule out global plots. In fact, I'm toying with the idea of getting a tee-shirt made that says "Area 51 Crash Survivor". I figure you lot are all bizarre enough that I have to be on the wrong planet!

My next task was to make some battery connectors. The first went together very nicely. The second fell apart. It must be that kind of day I figured. Sure enough. I connected the output of my solar panel to a second charge controller and hey presto... Nothing happened. Then I realized, the second charge countroller might be faulty. That was the one that had a bashed screen. I reconnected the wires and still though there is power flowing, the solar sign is not illuminating.
If you look carefully at the photo above at high resolution you'll see the solar panel symbol displayed at the bottom left of the LCD screen on the top charge controller but not on the bottom model. Disconnecting the battery displays an incorrect voltage from the solar panel. In the end I figured I have a duff charge controller. That didn't surprise me given the bashed screen. Without wasting further time on it, I removed it and eventually noticed I'd wired the solar panels to the output and the output to the battery. There was no harm done even though I blew the protective fuse in my battery pack (thank heavens for the fuse) and overheated my CPU fan, which fortunately still works. It also reminded me of exactly why I have several fire extinguishers aboard.

Going back to what I said yesterday, I'm giving the charge controllers and batteries that have been pretty well poo-poohed by Eric a good go. I have a 35AH battery to hand but if these can keep me going until winter when I can get under the bus to configure a single battery system then its great.

Interestingly, I noticed with two charge controllers connected to the same solar panel but to different batteries, the voltages displayed as battery voltages are identical despite the batteries being of very different voltages. I have very much a feeling that one has to use one charge controller and just combine the output of the solar panels. My controllers all claim 20A or 30A output. We'll see about that though. I am still not really convinced that these all in one gadgets such as solar controllers are really worthwhile.

I did manage to install my second CPU circulation fan. That's now mounted above the bedroom desk. As the fan is wider than the 2x4 that supports it, I had to go for a different design than the one I used for the mount on the other fan.
As can be seen, I had to offset one of the supports into empty space. That'll probably help with circulation. I'll just have to see how many arachnids think it's a clever idea to build a home behind it!

So, today I didn't get all my tasks completed. I did have to rethink my idea of charging extra batteries off a second charge controller attached to a single solar panel. In fact it's looking like the multiple battery idea just isn't going to work. I think I'm better off with the single 35AH battery, putting a timer on my ventilation fan so that it goes for just 15 minutes at a time with 45 minutes between runs. The door lock will for the moment remain as an AA powered device. I can't recall when I last charged those batteries save for that it must have been months ago. The CPU fans need individual on-off switches - more as a safety measure than anything else. I need to install a pair of USB charging hubs - one in the bedroom and one in the galley. As for total power usage, my extraction fan is 2.5A, my CPU fans are 0.5A each and the USB hubs (assuming both have two 2.1A sockets) will total 8.4A for a grand total of around 12A. I'm not too worried about the charge controller getting overloaded. I can easily use the controller output to power a relay to connect devices directly to the battery. That has the advantage that I can bypass the limitations of the relay while maintaining a safe environment.

The 50 cal box will remain a holder for my 35AH battery. That battery won't be used until I can get my solar panels linked and get down to a single charge controller. The redundant charge controllers will just have to go into a box. You might be correct for thinking I don't know what I'm doing. The fact is, I'm finding out as I go along by trial and error. If I build another motorhome then I will most likely do it completely differently, using the knowledge gleaned from this one to achieve Nirvana with the next.

So, aside from putting wiring down the beam for the new fan, I'm pretty much done. I'd like to install switches for safety so I can just cut the fans off individually if there's an overheating issue again. Other than that, my fans can remain using the 10AH and 5AH batteries. I won't put USB charging in place until I can get my single battery and wiring installed.

No comments:

Post a Comment