Wire guage help???

EAdamsEAdams Solar Expert Posts: 34
I have a Interstate AGM 74ah 12v battery that I keep charged from (4) 15w 1amp PV panels. I am wanting to use this battery to power 12v LED lights in each room in case of power outages.

What guage (and type) wire should I use to go from the battery to each LED light fixture? I guestimate 50ft for each run from the battery to the light fixture in each room.

I am also wondering if anyone has done anything similar and could they post links or pics showing what they did starting from the battery (switches, fusing, etc) to the fixture side.

thanks guys!!:cool:

Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Wire guage help???

    you could just about use anything if wired for individual lights. i roughly guesstimated a draw of 150ma (most small leds draw about 15ma, but know what yours will draw) and 100ft of 24 gauge wire (telephone type wire or cheap speaker wire with 50ft on the + lead and 50ft of the - lead) and it returned a voltage drop of .387v. at 12v. this is about 3.22%. now if you are using power leds or longer runs then you might want larger wires like 22 or 20 gauge. of course you can use something like 16 or 18 gauge if you like as it is common too.
    do be sure to put a fuse and switch near the battery for each led light run of wire.
  • cb1000ridercb1000rider Registered Users Posts: 6
    Re: Wire guage help???

    EA:
    A few things:
    1) No one can calculate what you need without knowing how much draw (amps or watts) those lights take.

    2) Consider not running in parallel.. Likely you can do them all in a single run as long as they're low draw enough and the switching mechanism works for you.

    I have LEDs on a gate (small implementation) - just with some simple resistors I was able to drop their draw way down (by a factor of 10x) with only a minimal reduction in light.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Wire guage help???

    my comments in bold.
    EA:
    A few things:
    1) No one can calculate what you need without knowing how much draw (amps or watts) those lights take.

    yes, someone can as i did address the draws and i based my calcs on more or less worse case scenarios with a statement of various led draws and i did say for him to know what it is his lights draw for a comparison.

    2) Consider not running in parallel.. Likely you can do them all in a single run as long as they're low draw enough and the switching mechanism works for you.

    he stated individual parallel runs i suspect due to the locations of the led mounts. i don't know his particular setup, but thinking of my own i think it may not be wise to zig zag the wires that much just to have a series connection and as with all series circuits if one would go out, all would go out.

    I have LEDs on a gate (small implementation) - just with some simple resistors I was able to drop their draw way down (by a factor of 10x) with only a minimal reduction in light.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Wire guage help???
    EAdams wrote: »
    I have a Interstate AGM 74ah 12v battery that I keep charged from (4) 15w 1amp PV panels. I am wanting to use this battery to power 12v LED lights in each room in case of power outages.

    What guage (and type) wire should I use to go from the battery to each LED light fixture? I guestimate 50ft for each run from the battery to the light fixture in each room.

    I would just treat it as a regular low-voltage lighting system and rig it accordingly - so any wire used for lo-vo lighting would be fine.

    I personally like the direct burial 12-2 and always keep some on hand.

    http://www.homedepot.com/h_d1/N-5yc1vZ1xhc/R-100087365/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053


    You also need to keep in mind that your system could be carrying as high as 14.4, 14.7 or even 15 volts - so make sure that your LEDs are setup to handle voltages that high or they probably won't last long. If it's rated for automotive use then it'll normally handle the higher voltages.


    Here are a couple of places where you can find LEDs and switches and whatnot:

    http://www.oznium.com/
    http://www.superbrightleds.com/
  • EAdamsEAdams Solar Expert Posts: 34
    Re: Wire guage help???

    Thanks for the ideas/help guys. I have the battery centrally located in the house and plan to run from there to each room individually.
  • EAdamsEAdams Solar Expert Posts: 34
    Re: Wire guage help???

    I just went through a box of wire, etc and found a 50ft roll of 20AWG speaker wire!! That should work right?? ;):D

    niel wrote: »
    you could just about use anything if wired for individual lights. i roughly guesstimated a draw of 150ma (most small leds draw about 15ma, but know what yours will draw) and 100ft of 24 gauge wire (telephone type wire or cheap speaker wire with 50ft on the + lead and 50ft of the - lead) and it returned a voltage drop of .387v. at 12v. this is about 3.22%. now if you are using power leds or longer runs then you might want larger wires like 22 or 20 gauge. of course you can use something like 16 or 18 gauge if you like as it is common too.
    do be sure to put a fuse and switch near the battery for each led light run of wire.
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Wire guage help???

    i say go for it, but also i have to ask what kind of current do you plan on putting through it as you've yet to say?
  • EAdamsEAdams Solar Expert Posts: 34
    Re: Wire guage help???

    Not sure. Looking at:

    http://www.superbrightleds.com/cgi-bin/store/commerce.cgi?product=UTIL&cart_id=9834111.15342#UC-LX1

    on the "round Utility LED Light" for $3.9X each. (3) LEDS. Should be little draw???
    Hight-end might be a 12v LED car dome light. Not sure of the draw there either.



    niel wrote: »
    i say go for it, but also i have to ask what kind of current do you plan on putting through it as you've yet to say?
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Wire guage help???

    i say do it still as even going with 250ma from a 3w led and 50ft run of #20 wire would give a .255v drop for 2.12%. if you plan on paralleling more on the same leads this would increase the current draw and if the leds are 3w this would be too much for a good v drop percent. individual leds run separately are fine with the #20.
  • EAdamsEAdams Solar Expert Posts: 34
    Re: Wire guage help???

    Great! Recommendation on fuse for all 3 legs together? Gonna fuse after the battery and split it 3-ways after the fuse.

    Battery->FUSE>split to 3> switches>kine runs>LEDS


    niel wrote: »
    i say do it still as even going with 250ma from a 3w led and 50ft run of #20 wire would give a .255v drop for 2.12%. if you plan on paralleling more on the same leads this would increase the current draw and if the leds are 3w this would be too much for a good v drop percent. individual leds run separately are fine with the #20.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Wire guage help???
    EAdams wrote: »
    Great! Recommendation on fuse for all 3 legs together? Gonna fuse after the battery and split it 3-ways after the fuse.

    Battery->FUSE>split to 3> switches>kine runs>LEDS

    The fuse is to protect the wire. #20 is rated at 1.5a max. So you would use a "1.5a or less" fuse to protect it.

    Tying three legs together and then using a 3a fuse would be completely wrong, since any one of those legs could smoke with 3a of load (double what #20 is rated for) before the fuse blows.

    If it were me, I would probably just use a 1a fuse on each leg.
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