12V appliances

Discussion in 'Off Grid Living' started by fortunateson, Mar 27, 2010.


  1. fortunateson

    fortunateson I hate Illinois Nazis!

    Starting to research setting up my own solar energy system and I'm looking at appliances.

    Clearly it pays to stay mostly in 12v instead of inverting to 120vac.

    Mainly I've been wondering about converting a fan (or other 120vac motor to DC) Theoretically, this should be doable since most motorized AC appliances don't have true AC motors, but DC motors connected to a rectifier.
    However, the rectifier puts out 120vdc.

    So I should be able to strip out the rectifier and run it on straight DC, IF I can bump the DC voltage from 12vdc to 120vdc.
    Is this possible? Is there even a device to do this?

    Anyone know? Thanks in advance.
     
  2. melbo

    melbo Hunter Gatherer Administrator Founding Member

    TN Andy would know. I know that while you would have some inefficiency in stepping up from 12DC to 120 AC, the main thing you need to keep track of is watts. A 60 watt incandescent consumes the same energy as a 60 watt 12 VDC Halogen, etc.

    Or so I think
     
  3. Allen

    Allen Monkey+

    If you want DC powered appliances, look in RV & Marine catalogs. I'm a Yact technician & work with 12/24vdc as well as 120/240vac systems.
    Norcold makes refrigerators that run on dc & have a convertor attached for ac use. The system perfers ac, but switches to dc when ac goes out.
    Lots of fans/blowers come in dc. They even make dc coffee makers, a must have.
    Look up West Marine. It will give you a good idea of what's out there. You can then try to find them cheaper elsewhere if you can.
    The neatest thing I've seen is a motorized icechest, dc or gas powered. You can ride on them.
     
  4. Allen

    Allen Monkey+

    I recently installed some inexpensive LED lighting on a boat. The produced lots of bright light for the power draw. About 12" long. They are from SeaMaster Lights
    The 50w strips were about $50.00 our retail, which means probably cost $20.00 if you look hard enough. You could read by them.
    I also installed some Seachoice 4" light strips that are good for emergency or courtecy lighting, can run them all day for almost no power. At our retail of $18.00 each, means you can get them for under $10.00. They would be great in the outhouse.
     
  5. gomer

    gomer Hooligan

    If you plan on installing your panels on the roof of the building you'll be using the appliances in, by all means stick with 12VDC. Better yet, go 24VDC. But if you plan on transmitting that power beyond that (16/2AWG ~100ft, 18/2AWG ~ 50ft @2a), you'll want to step up to high voltage or just invert to AC. You may lose a little to entropy but you'll lose far less energy than if you tried to transmit DC that far.
     
  6. fortunateson

    fortunateson I hate Illinois Nazis!

    Was wondering about that. Thanks.


    Update:
    I've decided that I'm going to set up a small solar backup system. Problem is we have lots of trees so I'm picking a part of the roof that gets sun most of the day.
    I've got 2 deep cycle batteries for about 150ah total.
    I plan to keep those and an inverter in a storage closet or attic and run a 120vAC receptacle to each floor of the house.
    The idea being that there will always be a small bit of standby power available in case of a blackout. Just unpplug and replug stuff into the "standby outlet".
    I don't want to get involved in a whole grid-tied inverter deal. Too much money right now.
    Now I just have to find a good set of panels that will at least partially charge my batteries each day.

    Question - how will an uninsulated attic affect my batteries (20 deg.F - 120 deg. F)?
     
  7. gomer

    gomer Hooligan

    What your thinking is a good plan for starters. Easy enough to expand on should you decide to in the future. Just swap out the inverter and presto: more capacity.

    High heat will shorten the life of the batteries and it doesn't help the inverter any either. Store them in the garage or in the cellar. Also, invest in a good charge controller so you won't over charge your batteries. Do yourself a favor and go with a pair of AGM batteries. They can handle heavy charge/discharge cycles and store far better than anything you can get off an Autozone rack. Plus they're essentially maintenance free other than keeping the terminals clean.

    EDIT: Look for multiple junction, thin film or crystalline silicon cells. These will give you the most bang for your buck.

    EDIT..again: Skip the RV and yacht catalogs. There are companies that specialize in 12VDC and alternative energy appliances.


    • <cite>www.offgridappliances.com</cite>
    • <cite>www.oasismontana.com</cite>
    • <cite>www.solardyne.com</cite>
    • etc
     
  8. fortunateson

    fortunateson I hate Illinois Nazis!


    Thanks.

    The charge controller was a given - just forgot to mention it.
    I guess the whole setup will go into an inside closet then to avoid the heat - done.

    Here's the best deal I found on panels so far:
    RAMSOND 120 WATT W 120W PV SOLAR PANEL MODULE 12V RATED - eBay (item 360253874524 end time Jun-16-10 09:42:36 PDT)

    I was impressed with the fact that they're mono-crystalline. Definitely made in China, but for the price and free shipping, may be worth the chance.
     
  9. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Be careful with that, batteries give off gases when charging. IIRC, one of them is hydrogen, not a good thing to contain in a closed space. No, I do not trust sealed cells. YMMV.
     
  10. fortunateson

    fortunateson I hate Illinois Nazis!


    Thanks for the reminder, and yes, it is hydrogen - and oxygen. They act as an electrolysis device when charging - you can even hear them bubbling.

    Might just have to stick them in the attic and see how they do.

    Really depends on the cost of cabling I'd need to mitigate power loss.
     
  11. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    I would strongly recomend that you do not store your batteries anywhere inside of the house, as when they are charging they will give off gases that you and yours would not want to breath. Acid type of gasses. Also 12 volt or DC current requires a much much larger typeof stranded wire to go any distance at all.
     
  12. bnmb

    bnmb On Hiatus Banned

    Yup...DC is not a happy traveler, and if forced to travel, a big looser...
     
  13. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    You would want to install your solar panel on the roof , where it best catches the most sunlight for the longest part of the day. Then run say 10 ga. stranded wire pos and neg down into your garage. That would go into your charge controller, hopefully a good one, and from there into your batteries. Next you would run a HEAVY Welding type cable first to a large fuse and then into your invertor. Now you have a little bit of ac power to play around with. Do NOT connect the ac power to your incoming service or after the fire dept puts out the fire you will be getting a very large bill to replace at least one power company transformer and a little bit of the highwires you just melted. [peep]
     
  14. We are building an off-grid cabin. We prefer redundancy. For lighting we have 12v florescent screw in bulbs as our primary lighting, 115v T-8 florescent lighting, Propane lighting, Aladdin and other kerosene lighting and rechargeable lighting. We have a propane stove from a camper and an old Montage wood cook stove. We have a 12v propane forced air furnace from a camper and an old Ashley wood heating stove. The Frig works on either 12v, 115 volts or Propane (from a camper) We have a composting 12v/ 115v (modified) Sun Mar toilet in the main bathroom and a sawdust toilet in upstairs bathroom. The kitchen and bathroom fans are 12v bilge blowers with dual check valves. They move more air than the ones in our on-grid home. We also use one to purge the battery box. Batteries are charged with Solar, Wind and Gas / Propane Generators.
     
  15. dragonfly

    dragonfly Monkey+++

    After a LOT of head banging over this ourselves, we chose to stay with the 120vac invertor systems. It's too costly to run much of anything with a real amperage draw on 12 volts. The cables cost a lot and are heavy and ugly to boot! We can easily run most stuff with 4 battereis and 2 solar panels, so we have discovered. I got away with only 2 automotive batteries, as I did not use them a lot and not consistently. They had plenty of time to trickle charge and when there were in use I never had more than maybe 40-45 watts draw at any given time, and for short periods.
    The cables alone to connect all the batteries to the massive ($400) invertor, and to the wall breaker panel, cost a chunk of change. We chose to stick with the "original" wiring in the mobile homes ( 12-2 with ground) Romex, and use 110/120 vac. So far, we have been happy with the results of that system. I searched for and found lot's of 12vdc appliances and such, but was not happy with the wiring problems and the additional costs we encountered for them. We took regular "old" mobile homes and simply converted them easily with a large invertor system, to run everything from TV's to refrigerators, to microwaves. Using the invertor to connect directly to the breaker box, saved us from additional fusing and other headaches as well! All the appliances and wall outlets are the same as they came in the mobile homes.
     
  16. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    12 volt dc appliances

    Look, I have lived off the grid totaly now for about 15 years. I have a little bit of practical exp. in this dept. I would strongly urge you to go AC as the first thing you will be up against is expense with the 12 volt. RV stores will really sock it to you for app. and even then , you will be limited to what you can obtain. When you go AC , sure you need an invertor to do this, but then regular wire and all your appliances are avail at any store you would normally go to. DC wiring needs to be much heavier to carry the same amp. as AC, which is another downside to dc. You can buy a GOOD invertor from a company called Xantrax , which used to be Trace and will last you for many many years. Much safer the grid power as they detect a short in a Nano Second, which means they will shut down to protect you from electrocution much faster then even a standard GFCI circut. Consider it at least.
     
  17. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    I would recommend 6 volt deep cycle batteries such as Trojen T-105. You wire them in series and paralell to obtain 12 volt, and they will last much longer then anything else. I run a bank of 18 of them, and it allows my mobil home to function pretty much like any "on grid" house all the time. Biggest problem is when there is no sun and also no wind, and the back up generators will take care of that in very short order. What kind of Massive invertor are you using ? $400.00. That does not sound like a very good invertor. Not picking , just trying to help.
     
  18. If you are going to build a serious long lasting system look into Forklift Batteries. They will last much longer than any Trojan Battery.

    To be honest you can't purchase a decent inverter for $400. You want to save your money and purchase a good "Sine Wave" inverter. Your appliances will thank you and in the long run so will your pocket book. There are plenty of good articles to explain why you want to only get a "good" sine wave inverter.
     
  19. This might be something to consider Xantrex Prosine 1800 (12 V w/AC hardwire & transfer switch) Inverter #806-1802 806-1802 / UP Price $983.79 UltimatePassage.com
     
  20. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    +1. A "good" inverter will approximate a true sine wave better than a cheap one. Theoretical discussion: Inverters are digital devices that step change DC to AC rather than generate a pure sine wave. The more steps, the closer to a sine wave they can get, and the pricier the inverter becomes. Motors and other things do NOT like too few steps, each step makes them think they are freshly starting and current draw is too high; one gets to burn out rather too soon. The closer to a pure sine wave, the better.

    What about batteries such as cruising sail boaters use? (Not talking about trolling motors here --)
     
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