Transfer switch for 12v emergency lighting?

Discussion in 'Electrical Forum discussion & Blog' started by Bassist58, Dec 9, 2012.

  1. Bassist58

    Bassist58 New Member

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    My project is merely in the thought processes right now. I want to make an emergency lighting system in case my power goes out. I'm thinking of using a 12v deep-cycle marine battery charged by a solar panel (or small wind generator) to light a string of LED's inside my house.

    Is there something that can turn them on automatically when the power goes out? All of the threads I've searched seem to deal with transfer switches used with generators that are somehow tied to the grid. (And nightmare stories of death by electrocution.) I just want something that I can plug into a 110 outlet that detects when the power goes out and turns on my lights. Sounds simple to me, but that is never usually the case. Short of changing the batteries in a flashlight, I have no experience with electrical stuff, but I want to learn.

    Thanks so much in advance!
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

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  3. Bassist58

    Bassist58 New Member

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    jwelectric

    Thank you so much for the quick response!
    Looks like a great product, except for the wiring into a box thing. Actually, the L-1-Plug http://www.lightworld.com/products/L-1-Plug.html (link on the page you gave me) is more my speed. Much less work and cheaper than my original idea. I had no idea that these existed.
    Thanks so much for the info!

    Brian
  4. Bassist58

    Bassist58 New Member

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  5. hj

    hj Moderator & Master Plumber Staff Member

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    That is okay if you want a "single" light, but to operate a string of lights you need a "normally closed" relay which is kept "open" by your house's electrical system and "closes" when the power fails, thus turning on your lighting. This is NOT a "plug in" item, other than for the power to control the relay.
  6. Bassist58

    Bassist58 New Member

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    Thanks muchly, hj.
    This was what I wanted to know about, originally. While the above products will suffice until I actually start my project, the project itself is something that I've been wanting to do just because I thought it would be cool to do, but mostly to learn.
    Now, on to learn about relays.

    Thanks again,

    Brian
  7. leejosepho

    leejosepho DIY scratch-pad engineer

    It would be easy to hold a normally-closed relay open with 120V, but the size of that relay will be determined by the DC load you are switching...and that factor could lead to needing to use a large relay that would be energized and using more power than you will need to keep your battery charged. To avoid some of that overhead, you might consider using a light/dark sensor to decide whether the emergency system is even available at all.
  8. Bassist58

    Bassist58 New Member

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    Location:
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    Okay, now you've confused me. But I have yet to do research on relays. Sounds like you are saying that the relay will drain my 12V battery. And I think a light/dark sensor would just keep me up at night.

    I'll be back next week with more questions after I do more research.

    Thanks,

    Brian
  9. DonL

    DonL Jack of all trades Master of one

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    I have built controllers like you are wanting in a Metal Quad Electrical Box.

    You can put 1 dual outlet if desired, and have the rest of the room for parts.

    You can do it with 1 relay and a fuse or three.

    Just use a Double Throw relay , and double pole or more for increased current if needed.


    Be careful playing with electricity.
  10. BobL43

    BobL43 DIY Senior Member

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    Bassist,

    All this discussion of the controls issues, but the unit(s) you and JW linked to amount to only a little less than 11 watts of incandescant lamping. Is that enough light for your needs? Did I read those specs correctly? I just read you other post that links to the LED plug in, but even that has really low light output, no?
    Last edited: Dec 12, 2012
  11. leejosepho

    leejosepho DIY scratch-pad engineer

    Maybe I was second-guessing a bit. The idea of a solar charger means you do not have to purchase power to keep your battery charged, but then that savings will be offset by power needed for keeping a relay energized in the "open" position until emergency lighting takes over. And as to a light/dark sensor, the idea there is to let darkness do two things:

    1) Make the emergency lighting available;
    2) Activate the relay to keep the 12V lighting off until it is actually needed.
    Last edited: Dec 12, 2012
  12. DonL

    DonL Jack of all trades Master of one

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    A solar charger would be cool beans.

    If a double throw 2 or 4 pole relay is used, then 1 NO connection can power the battery charging system when AC is available via a AC outlet mounted on the Metal Fuse protected outlet Box.

    You could switch the battery charging over to a solar panel, on lose of AC power if wanted.

    Sounds like a project to put on the Electronics Forum, Maybe Bob can point out some cool design ideas.

    Safety comes first so never forget the fuses in any design.

    I think every home should have a LV DC emergency supply available in every room.

    Led lighting for DC systems is the way to go.
  13. Bassist58

    Bassist58 New Member

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    Location:
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    I agree totally.

    I am scrapping the idea of automatically turning the system on when the power goes out. I am now looking into using LED strips (16' lengths chopped up and distributed throughout my house, more like mood lighting), still powered by a 12V battery (solar charged), but using a simple on/off switch which I could find in the dark, if necessary. This way, I could just use the lights whenever I felt like.

    Thank you all for your input. I will do more research and post my final design idea in the Electronics forum.

    Thanks again!

    Brian
  14. BobL43

    BobL43 DIY Senior Member

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    Don, I've kind of lost interest (ah, a litttle, anyway) of designing and building projects. These days I try to find store bought items to suit my needs. They just don't last long though and are all made in China with toxic materials.
  15. BobL43

    BobL43 DIY Senior Member

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    Location:
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    Brian, that would greatly simplifiy things, but then you'd have to search for the switch when the power fails and it was completely dark, lol. Automatic is better, I think. Maybe a glow in the dark switch otherwise. They stay visible for a short time after the room goes dark. Enjoy your project:)
  16. Bassist58

    Bassist58 New Member

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    Location:
    Pittsburgh
    Thank you.
  17. big2bird

    big2bird IBEW Electrician

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    The KISS principal is always the way to go.
  18. DonL

    DonL Jack of all trades Master of one

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    Location:
    Houston, TX

    I would not scrap the Auto idea.

    You could add 1 switch and make it all work.

    The switch could be a test switch that just kills the relay, and makes for a good monthly test for your battery system.

    Don't give up yet.


    The Electronics forum, may be a good place for some Safe Low Voltage design ideas.

    Fuses, Fuses, Fuses. don't let the smoke out of your design.


    If you don't get help on this Forum you can get help on http://www.winforce.net/forum/electronic-talk
    Last edited: Dec 16, 2012
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