The Easton “Off Grid” Project
Twenty years or more of reading about Solar Power and other off grid power producing equipment doesn’t teach you what you’ll learn experimenting with your hands all over the equipment. Of course you’ll need to be curious and log all those questions that enter your mind as you go. Good test equipment helps too, because you have to trust the infomation you collect.
How does a guy know what to buy and what works best? A good nose for efficiency is helpful, maybe we mention a few things to stir your curiosity?
I had a customer who was using a 10 KW generator head to supply power to his built in inverter charger. He had about 14,000 hours of operation on it before trouble developed, the slip ring started wearing and soon got so bad it had to be pulled from service. He has yet to figure how he can make an economical repair.
His beautiful mountain setting in the Central Cascades has many winter and spring days that are overcast and the solar panels just don’t keep up with the demand for the household and the satellite connected workstations to make the digital commute to work at Sun Microsystems.
The Customer decided to replace the generator with the smaller Utterpower PMG and immediately noticed a savings in fuel and far shorter run times to charge the batteries why?
The answer is we designed the PMG to produce a nice strong peak voltage at 60 HZ. We also use high temp magnets that cause the generator to work with a very respectable voltage droop from no load to full load, If we look at the power available to the charger from the PMG as compared to a hardware store generator or similar, we see that a lot of generators really provide a far lower voltage and thus less power to the load. If you’ve spent anytime on the Utterpower website, you know we love the “Kill A Watt”, there’s a post devoted to it here on this site. Take one along anywhere there’s going to be a generator and plug it in. There are generators with peak voltages so low that some inverters don’t even recognize them when you plug one in!
This leads to our example of what you need to look for. There are losses all along the way when we convert energy from one form to another, this is also true when we convert one form of electricty to another.
If we look around on some of the solar or off grid sites, we’ll quickly find a transformer being sold to the folks that can’t use their generator at all for battery charging, or it takes so long they can’t afford the fuel. This Transformer they sell is designed to raise the voltage five percent or so, and now the inverter charger is happier. But if you understand the nature of our physical world, nothing is for free, the transformer cost you a good chunk of money all right, but it also adds measurable losses to your system and now you need burn more fuel per KWH to make up for the losses you inserted into the circuit. It’s really all about the cost of your fuel and the conversion of that fuel into a KWH of energy. But there is one more factor that’s very important, and that’s the initial cost of your equipment. you’ll hear the hopelessly confused talk about free energy from the sun, they seem not to notice all the costs associated with collecting this free energy, nor do they understand the fact that we need add up all of our costs and spread them across the lifetime of our power plant and pro rate out the cost per KWH.
Click to read other articles on > Easton “Off Grid” Project
The Cowiche Cabin Project
We built our high mountain cabin on ground covered with volcanic ash. At the time, my wife and I wondered how long it would take for nature to hide the evidence of the latest eruption of Mt St Helens. That was 1980 and our cabin has undergone many changes since then. Come to think of it, so have we. As we grow older; we seem to be attracted to some of the luxury items; like electric lights, an indoor shower; and although the satellite dish is not a must, it’s nice to connect with the rest of the world from such a remote place. This all becomes possible with a modified sine wave inverter, I bought a unit from donrowe.com, it really runs everything we need at the cabin, and then some. And most important, it’s quiet, why go where it’s quiet only to make noise with a generator?
All these comfort items triggered the need for a better way to charge batteries. We have a little Coleman generator designed for light duty; with a 10 amp 12 volt charger built in; but one quickly learns that 10 amps isn’t much for charging batteries if you’re running a 19 inch TV, direct TV receiver, compact fluorescent lights, water pump, and other miscellaneous loads. Sure; you can buy a battery charger and power it via the AC outlet, but is there a better way?
My home made gas powered charger is based on a military generator with a bad Gen Head, I saved the frame and the engine, the parts I added were painted Army Green, and some might think it came this way!
After mounting a cheap aluminum 6 inch ‘A’ type pulley to the crank, I welded a bracket up for the auto alternator and found a small belt to fit the need. I hooked the unit to a junk battery and noted 75 amps of charge rate. If my basic math holds up, that means I could deliver the same charge to the batteries in 4 minutes versus 30 minutes it would take with the Coleman charger, WOW, that’s what I call noise reduction if nothing else. I made up some leads and decided to haul this charger up to the cabin next trip.
It was Elk hunting season, three of us packed up for a 10 day hunt out of the cabin. The Gen. set got thrown into the utility trailer and buried with supplies. When we arrived, we set up two deep cycle batteries outside and dropped the Gen set a few feet from the batteries. One evening; we were watching a movie and the inverter sounded it’s alarm; “low voltage!”, “feed me or I’m going to dump your Dish programming!”. I grabbed the flashlight and went out into the night to start the Gen. set. Where’s the rope? I hadn’t returned it to it’s place, I shined the flashlight around looking everywhere. The wind was cold and blowing about 25mph, I could see snow flakes in the beam of the flashlight. I found the spare starter rope and wrapped it around the pulley, six pulls later the set was running and I bolted for the door. I quickly claimed the seat next to the wood stove and caught up with the movie. In the back of my mind, I was planning the next enhancements to the charger, “going out in the middle of the night to crank up a cold Gen Set is not my idea of fun”.
Click to read other articles on > Cowiche Cabin Project