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Home Forums General Discussion DC powered lights and fans

This topic contains 20 replies, has 12 voices, and was last updated by  elnav 6 years, 3 months ago.

Viewing 15 posts - 1 through 15 (of 21 total)
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  • #36693

    basserben
    Participant

    Hello all. I just bought 10 acres of wooded land in south west Louisiana. I plan on building a small 240 sqr foot cabin to use as a camp and possibly my retirement home. I want to build it on the very back of the 10 acres so hooking to power and water is out. Don’t what to be dependant on anyone anyway. My plan for now is to get a small, quit, generator that i can use to charge a few batteries. I want to use the batteries to power the cabin. I would like to be able to run a few led lights, phone & laptop charger and most importantly a fan or two. (it get HOT down here.) I would like to be able to run these things for 2 or 3 days before needing to fire off the gen and recharge the batt’s. This is where the questions start. How many batteries do it need? What kind of 12v lights work best? What gauge wire should i run from the batteries to the switch panel for the lights and fan? (i know very little about DC wiring.) What size wire from the switch to the lights? What kind of fan motor should i get? I was thinking about using a motor from a trolling motor and adding bigger blades for more air movement; but if there is a more energy efficient DC powered fan motor out there, please let me know. I’m open to any and all advice.

    #40841

    elnav
    Member

    In my opinion going with DC lights and appliances wired direct to one central battery is a mistake. The reason being is efficiencies and wire losses.

    Presumably you want some solar panels since you are located far enough south to derive some benefits.

    You would be better off going with one central inverter and battery bank and distributing the power using conventional 120V AC wiring. This kind of equipment is sold everywhere. If you need help wiring lots of people will know how, because it is familiar house hold wiring.

    I spoke about efficiecnies. There are many more companies now striving to make energy efficient household appliances than there are DC appliances makers.

    If you have a wire size calculator it will be obvious that to deliver the same wattage to a DC fan for example you need to runmore current than if the fan was AC at 120V. Therrefoer you will likely end upspending far more money on bigger copper wires than if you went with standard 120V appliances.

    If you do end up with a DC device such as an LED light you can uses a step down transformer to get 12V or 6V from the 120V ac. In fact you could probably fish such power supplies out of the garbage because so many people toss out the old charger for a cell phone when they get a new one. Garage sales and good will stores typically charge 50 cents to a buck apiece for such power cubes.

    If you buy an RV or marine inverter it will in most cases be a combination inverter charger so now you only have to add the generator you figured on needing anyways. But the RV / Marine charger is far more efficient tnat a typical charger you buy at NAPA or WALMART.

    That should get you started but if you have more questions please ask.

    #40843

    basserben
    Participant

    Thank you so much for the reply, but i think i’m a little more confused now. I realy am clueless when it comes to AC wiring. And the extent of my DC wiring is rewiring lights and pumps and trolling motors in boats.

    I would love to be able to put a few solar panels up but due to the heavy tree coverage it is not an option.

    So your saying i can wire the cabin with standard 120ac plugs, lights and fans, and run it all to a inverter and than to batteries? I dont know what an inverter is. lol I swear, after think about all this elctrical stuff i’m about ready to go with lamps and candals instead. If i go with 120 dont i have to meet certain building codes and such? I’m trying to avoid all that. This is only going to be a hunting camp and not a residence. Not yet anyway.

    Please reply back. I’m eager to learn as much as i can on this subject. A link to a wireing diagram or website about doing this type of wireing would be helpfull. Thanks.

    #40844

    elnav
    Member

    Oh boy that is what I was afraid of. So many people want to go do their own thing without knowing anything about it. ‘The Code’ is not your enemy its your friend. Most book stores I have been in has a DIY section and in there you can find a summary of how to fix and wired you house to “Code” Most jurisdictions do allow a home owner to carry out minor repair and additions to their house.

    Strictly speaking inspections are only called for if the home is connected to the grid, financed by a mortgage, or in some way involve other parts of society. Insurance inspectors may want to see an inspector’s approval but many off-gridders are self financed, self insured and by definition not connected to the grid. What inspector? But if you have followed the code what can they find wrong?

    When you see a ‘Code’ guide explain how to wire something you know you can find the relevant parts at a local store.

    What’s good about the code is the fact so many stores carry home repair books Handyman guides and the ‘Average Joe’s guide to the Code. Detailed explanations can be found everywhere. ASk some trades guy if he knows how to wire up a wall switch and a light and he will say yesy. ASk him if he knows how to wire an off-grid house and he says no. In most cases ther is no difference and where ther are some differences product manuals and manufacturers usually provide guide lines.

    Looking fir schematic? Its at the book store on available online.

    I do not have enough time in a day to google, evaluate, and forward, all the thousands of hits you will get if you go look yourself.

    Code Guide books tell you the right way to wire up something so it will be safe. In addition many areas have a ‘Code Guide’ specific to the local jurisdiction not some generic thing that skips the important parts relevant to you.

    I work a lot with boats. I can tell you the industry insurance people report that most electrical fires originate in the DC section because for the same power levels more DC current is needed at lower voltages.

    If basic electrical terms and circuits confuse you, better get going and teach yourself the basics. Try googling “self directed tutorial on electricity”.

    I saw a new product brand (Samlex) at a local automotive store. The catalog had a whole series of typical applications notes. Other manufacturers do the same. These can teach you a whole lot about system assembly.

    Inverters are in essence solid state generators and the battery can be considered a fuel tank. It is not that complicated.

    #40845

    elnav
    Member

    Basserben wrote: “So your saying i can wire the cabin with standard 120ac plugs, lights and fans, and run it all to a inverter and then to batteries? I dont know what an inverter is. lol I swear, after think about all this elctrical stuff i’m about ready to go with lamps and candals instead.

    REPLY

    You are psyching yourself out: AC wiring in principle is exactly the same as DC wiring except you have to be more careful about insulation. And you learn not to work bare handed on live ccircuits. Following the standard house model makes it easy th find the right hardware at a store or salvage at some junk yard.

    Lots of people know about wiring houses so chances are better of finding sombody local who can answer your questions.

    #40871

    I live on 12 acres off-grid in the foothills of the Ozarks and have for several years. I use DC power in my 180 sq ft cabin. My lights are 5 watt squiggle bulbs (the came with 45 watt solar panel kits from Harbor Freight at $200 a pop which included a small charge controller, numerous adapters for charging cell phones etc., and 2 -5 watt bulbs) and the big lights – twin tube fluorescent (17 watts) are out of old RVs. My fans are $12 at Wal-mart and pull about 12 watts dc. O2 Cool camping fans are 12 volt and work great. I also have $150 12 volt ceiling fan that draw 12 watts. I disagree that you should invert and use 120v appliances. There are 9v DVD players, 3 volt wind up radios, portable cd players all can be plugged into the solar battery bank via the cheapo Harbor Freight charge controller.

    I have 2 larger inverters (4kw and 8kw.) I have used one once to plug in a 120v charger for my Droid cell phone. In 5 years I have not had any reason to use 120v at the cabin.

    My well is 12/24 dc submergible pump at 230′ that is powered with 60 watts of PV. 5 gallons a minute at 45 psi. I have the panels wired in series to keep 2 12 volt batteries charged which send 24v down the well. Draw is 1 amp at 24 volts.

    I have 700 watts of solar, a 4 battery (6v Trojans) battery bank that has about 4000 amp hours of storage. If I turn every appliance, including the propane refrigerator my total current draw for the cabin is 75 watts. Less than a 2 tube, 4 foot long florescent light. I use a 12 volt breaker box out of an RV for the house circuits. Old RVs are a great source of everything for a small cabin.

    I use my 56 degree well water to air condition the cabin. I took the air conditioner out of the dashboard of a Ford Explorer. I run a pencil stream of well water through the heat exchanger, turn on the squirrel cage fan and have the cabin ACd in a few minutes. I run the waste water on the garden. The temp of the exhaust water is 80 degrees. It draws 2.5 amp at 12 volt. The main thing is it takes and condenses the moisture (it is humid up here) out of the air as it moves the heat outdoors with the water. In a few minutes I have the cabin humidity free and down to about 75 degrees – which is VERY comfortable when it is in the high 90s with 90% humidity outside.

    I even have a solar outhouse. 50 watts of PV, small charger controller, 12v battery – indoor and outdoor lights complete with a small stereo.

    Living large in the Ozarks! LOL!

    Wolf Grulkey

    wgrulkey@aol.com

    #40883

    Anonymous

    I’ve been off grid for 16 yrs. using a 12 volt D.C. system. Not much need for A.C. except for a very few small jobs and I do these with a 400 watt inverter.

    Codes are good if you plan to sell somewhere down the line. If you plan to be there the rest of your time, do your homework and study low voltage wiring. It’s not that difficult. Just use fuses.

    #40887

    mainah
    Participant

    Instead of using fuses, aircraft circuit breakers would me more cost effective in the long run. Many light aircraft use 12V systems. Check the nearest aircraft salvage yard for sources. You won’t want to purchase them new. The price will shock you.

    #40888

    ReBoot2009
    Participant

    Basserben. AC can travel further with less electricity loss than DC. I have seen homes powered by DC because they can satisfy their lighting needs at a truck stop.

    elnav is right – “Therefor you will likely end up spending far more money on bigger copper wires than if you went with standard 120V appliances.

    If you do end up with a DC device such as an LED light you can uses a step down transformer to get 12V or 6V from the 120V ac. In fact you could probably fish such power supplies out of the garbage because so many people toss out the old charger for a cell phone when they get a new one. Garage sales and good will stores typically charge 50 cents to a buck apiece for such power cubes.”

    An inverter is what you need. Google it. There are a lot to choose from.

    If you are concerned about working with AC, you can usually disconnect the power before working with fixtures and plugs. This way you will not be in danger when you switch on the power, your new circuits might be in danger if they weren’t done right. :-/

    Hey, we’ve all fried a few circuits … really!

    AC is a better choice.

    Reboot2009

    GlobalFamilySurvival.com

    #40890

    elnav
    Member

    @mainah suggest using surplus aircraft breakers. If you have access to such fine and good. BUT many people do not. More to the point Carlingswitch manufactures about 90% of all DC breakers used world wide. They do not sell retail direct to consumers but just about every panel maker in the world uses their breakers. Even BEP from New Zealand.

    Another good source of breakers for DC off grid applications is Square D which is presently one of the few North American brand name type approved for solar installations. Siemens is another but I have rarely seen them used excewt in European equipment and they are twice as expensive as Square D.

    Fuses are not such a bright idea for several technical reasons and they cost enough to add up if you happens to get careless during installation. Cost of fuse and holder is no longer insignifucant. Most of the old surplus junk out there is just that, junk, and quite often not even fire safe. Somebody rejected it for good reason.

    Aircraft surplus becomes surplus because it no longer meets aircraft safety spec. If you are an engineer and can determine applicability for yourself fine. But for the rest you are simply adding your lack of knowledge to an unknown reject reason.

    Why jerry rig something instead of doing it right and be safe?

    #40929

    Trm
    Participant

    1st dc circuit parts can be scavanged from boats,

    aircraft, cars, Rv’s, trailers.

    most of this wiring and fusing is scraped due to what ever

    it was installed in not because it turned bad.

    Not too many people however would bother waisting their time

    you’ll spend more time re-engineering this stuff than buying

    new

    Simple math -higher voltage

    lower line loses, lower wire size, because lower amperage.

    Actual design wiring etc can be gleemed off the net

    Just remember it’s electricity and very unforgiving

    you might want to hire someone

    #41039

    Jim
    Participant

    Excellent idea for AC, loadarranger, I hope you don’t mind if I copy it at my place. It gets hot here in OK, also. Our home is wired for 12 V. and 120 (generator) but we rarely use the 120 except for AC. Got 12 V. fans from Walley World for 8 bucks each, 2 speed, low amp drain. Push enough air to work. Wired them with 14 ga. wire. Got 12 V lights from “Fish House Supply” on net, priced reasonable, wired them with 14 ga. wire (got a large spool of 14 ga. auto wire at auction). All give good service. Use 60 watt panels to power them. Run Laptops and satellite internet on 4 of Wal-Marts largest Marine deep cycle batteries. Have another 120 watt solar array will set up this winter to compensate for diminished sun. Elnav is correct in what he says, but if you’re more familiar with 12 V. marine systems, it might be your best, most economical choice. Just my .02, I’ve been off grid for about 30 years or more. It pays in the long run to have a system you understand and can trouble-shoot and repair yourself.

    #41100

    WrethaOffGrid
    Keymaster

    bump

    #41112

    markjack
    Participant
    #41116

    Trm
    Participant

    In India there are snake charmers who play with cobras

    1 bite and your dead in 30 seconds

    Electricity

    A bad shock will kill you instantly

    A mild shock can put your heart into arrhymia and you die

    when you go to sleep

    The electrical code is minimum safe practice

    and yes 12 volts dc has killed.

    Please do your research and please be careful

    and never work on a live circuit not only might

    you get hurt or killed you might have to explain

    how you blew up that expensive thing you just bought

    to your wife( and never live it down )

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