Monday, July 17, 2017

Dawn of the Dead

Feeling like death, I looked at the clock at 4am and texted the boss to say I wasn't coming in. I'm hoping to be well enough tomorrow. I hate missing work because I hate missing out on the opportunity of getting money. That left me with time to work gently on the bus.

After a lot of hunting around online to find relevant and useful information regarding my gel cell batteries, I drew a complete blank. Then in sheer exasperation I tried those god awful forums. Again, lots of people telling me to buy a new or bigger battery but no realistic or useful information. This is one of the things that makes me question whether people on forums walk their talk or just parrot others. If somebody walked their talk then I'm sure they would have suggested what I took as my eventual solution.
Looking at the charge controller, it has several settings of which three are noteworthy

  1. Load on voltage which is the voltage at which the controller commences powering a device.
  2. Load off voltage which is the voltage at which the controller cuts off the power.
  3. Panel off voltage which is the voltage at which the controller ceases charging the battery.
There are some less noteworthy settings such as some kind of timer that does something that the instructions do not adequately explain and a battery type setting that again the instructions do not explain. Of minor interest there's a built in thermometer but it doesn't seem linked to anything.

I'd read online on some allegedly expert website that the minimum charge level should be 11.9V. I'd already discovered my battery retains a maximum of 13V. Under those conditions I was getting 7 minutes out of my fan. Today, abandoning the online "expertise" for the nonsense it seems to be, I dropped the cut off voltage to 11.1V. By the time the fan had run for 20 minutes I concluded the air had been changed twice over in my motorhome. By that time, the voltage read 11.7V so I adjusted the cutoff point to 11.7V.  That works and wasn't that cheaper than doing what the people on forums said? It reminds me very much of what I saw written on the University of Wales college toilet door: "there's more information on a freshly squeezed turd than in this library". I'd replace library with internet, of course. 

Going back to my original calculations, my 10AH battery should provide 5AH of usable power. That means my fan should run for two hours.  That's more than adequate! Now I'll have to see how long it takes to recharge the battery. 

When my fan was running, I noticed the temperature inside the bus rose from 84F to 86F. Curious, I took the thermometer outside and found that indeed, it was 86F outside. I'll have to see if this also works on hot days. Maintaining the same temperature inside as outside is the Holy Grail for non air conditioned motorhomes. 

One of the things I've been trying is my small battery powered desk fan. It works surprisingly well.

I've already decided to mount permanently two CPU fans. One will be in the bedroom, above the desk and the other in the galley above the cooking area. They will involve some underbus wiring but not too much. They're non essential anyway. The essential is to get the extraction fan doing its job.

Thinking ahead, I ordered some thermal switches that will switch ventilation and fans on and off automatically. The cut on point is 25 degrees centigrade which works out at 77F. Below that there's little need for much ventilation other than the occasional purge of stale air.

Since Radio Shack went out of business, I've had to buy most of my bits from eBay. I don't like the fact I can't just walk into a store and buy the stuff I need. I don't like also that half the time I have to wait for delivery from that backwards walking pack mule driven by an illiterate Albanian peasant. 

The next stage now that I've conquered the fan issue is to continue dealing with the construction mess and to sort out my personal stuff. I'll also want to build my twin battery pack that'll keep my electronics charged. I'm pretty much there with my 12v electrics in the bus.

I still need to fix my right wiper. I know the motor and pivot work. My suspicion is the switch so I've ordered a new switch. If it's it the switch then I'll likely just have to rewire the motor. That's not a huge task, to be honest.

Having played with the battery and charge controller off and on all day while sitting between times at my desk in the bus, I'm now mystified. The battery readings on my charge controller seem to go up and down faster than a whore's drawers. This means that I could get 30 minutes out of my fan or just 5. It all seems so random!

In terms of temperature, it was still 90F inside the bus when it was 86F outside at the end of today's investigations. I'm not much closer to keeping the bus cool. I know my fan does suck out a lot of air. The air is getting out of the vents too. I'm wondering what the solution is.

I know there's a 4 inch blower rated at 270cfm and that if I put one on each side then I could vacate all the air from the bus in just two minutes. As they're 10amps each, that's a huge current draw that's way beyond my current cabling. For that I'd have to mount the battery closer to the fans. That's not to say it's not doable. In fact it is very tempting. I'd probably need to change my exhaust vents from mushroom vents to flap vents and do away with the screening on the outside, relying upon internal screening and bugs that enter just getting stopped by the internal screen and blown out the back.

A system with a 20A draw would definitely need the planned next component of my solar system which is a plugin extra source. My plan is to use my four solar controllers on a shared solar input. All of the solar power is shared. An external wind or solar supply could supplement onboard solar.

The four controllers would be used for.

  • Controlling the blower fan at the back and charging its battery.
  • Keeping the door lock battery topped up.
  • Keeping two internal fans going.
  • Keeping a portable power pack charged that's intended for charging phone, tablet, MiFi etc.
Some people would do all that from a single, large, battery. I prefer small batteries that are independent of each other. That means that the failure of any part of the system will not affect the whole system. Even the solar panels and external input will be individually fused and individually diode protected. Such a system allows more flexibility with changes, additions and improvements. Smaller batteries reduce the need for large solar arrays. When one battery is empty, the service stops until the battery is full. That means I won't necessarily lose door control when the ventilation stops or be unable to charge electronics when the internal fans stop. Sharing solar power rather than having independent panels means when things that aren't used much such as USB charging or the door lock have full batteries, the output can go towards ventilation. When the sun is stronger at one end of the bus than the other, all units can take advantage.

All I can do for internal ventilation right now is to install the fans and some of the wiring. The rest will have to wait. As far as the battery mystery goes, I'm baffled. I bought my 10ah battery new from a seller with a perfect reputation on eBay. My controller worked perfectly well with my CPU fans and 5ah battery. It could just be a duff battery. I have two 7ah batteries. I charged them both as much as I could. One stayed at 13v and the other at 12.9v. My 5ah has no problem maintaining 14.5v. Bizarre!

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