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Relay or no relay?

Discussion in 'Lighting' started by Rujack, Jul 18, 2020.

  1. Jul 18, 2020 at 6:26 PM
    #1
    Rujack

    Rujack [OP] Stop Global Whining

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    My kid dragged home a toy electric quad a couple weeks ago. It’s wiring had been butchered and needed a battery but being six, he was pretty stoked on getting it running. So I picked up a new AGM for it and got the wiring figured out and fixed. It was surprisingly complicated actually, but I’m pretty amateur in that department. Which leads to my question: is the use of a relay necessary to get full power to driving lights? We’ve been tricking it out a bit and I added two led 18w flood beams, tail lights and side markers, but they’re really, really dim when operating via the toggle switch. Is the switch very resistive? Just using these:

    https://smile.amazon.com/dp/B01MZ43N5O/ref=cm_sw_r_cp_awdb_t1_Oc6eFbSAZQHKD

    https://smile.amazon.com/dp/B07DKXBDKV/ref=cm_sw_r_cp_awdb_t1_ae6eFbDAM93XY

    https://smile.amazon.com/dp/B07VNDR987/ref=cm_sw_r_cp_awdb_t1_Ye6eFbP3XBTVD
     
  2. Jul 18, 2020 at 7:48 PM
    #2
    Rujack

    Rujack [OP] Stop Global Whining

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  3. Jul 18, 2020 at 7:53 PM
    #3
    koditten

    koditten Well-Known Member

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    Probably don't need the relay, but it will teach you about their uses.

    Relays are used everywhere. 12 to 140v a/c and on up.

    At being only $3-$6 each, it's not gonna break the bank.

    It will be a good opportunity to learn their uses.
     
  4. Jul 18, 2020 at 8:29 PM
    #4
    Rujack

    Rujack [OP] Stop Global Whining

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    Yep. I had a basic understanding of them, I just can’t figure out why the output is so low when I go through the switch.
     
  5. Jul 18, 2020 at 8:33 PM
    #5
    Empty_Lord

    Empty_Lord Wallet abuser

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    have you measured the voltage going to the lights to make sure theyre getting a full 12 volts? LEDs dont use much amperage. the switch in all honesty can probably handle the amperage no problem
     
  6. Jul 19, 2020 at 8:23 AM
    #6
    mrCanoehead

    mrCanoehead Well-Known Member

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    I'm wondering if the battery is actually 12 Volts?
     
  7. Jul 19, 2020 at 8:33 AM
    #7
    Empty_Lord

    Empty_Lord Wallet abuser

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    That is a good point
     
  8. Jul 19, 2020 at 8:52 AM
    #8
    davidstacoma

    davidstacoma Friendly Curmudgeon

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    Those toggle switches are rated for 20A shouldn’t need a relay at all. Your problem is likely in your wiring- what gauge wire did you use and where did you run power from? What is the wattage of ALL the lights hooked up to your switch ?
     
  9. Jul 19, 2020 at 8:59 AM
    #9
    synaps3

    synaps3 Wag more bark less

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    I ALWAYS use a relay. You should never put amps through a control switch if you can help it. That said, that's a guideline, not always an electrical requirement. This application will work fine without one. It's just a lot of amps flowing through a control switch.

    I'm not sure how much you know about electronics, so sorry if this is overkill. P=IV, or power = current * voltage. You know your power is 18w per light, so (18*4), and your voltage is 12, so your current = (18*4)/12 = 6 amps total. 6 amps is well within the rating of the switch, so that is unlikely to be the problem, and is proof a relay is not required for your switch.

    6A is definitely enough amps to heat up inappropriate gauge wiring, which would cause them to be dim. Too small of wiring will heat up and act as a resistor, dropping your voltage and eventually causing a fire hazard.

    This is a good chart:

    DC_wire_selection_chartlg.jpg

    Always round up. Consider the full length of the wiring if you have these wired in series (one after another); you may have 20+feet of wire if they're in a row like that, meaning you'd need 10A at 20 ft - 10AWG wiring if you want minimal voltage drop.

    One more thing, does the LED on the switch light up when it's on? If not, you may have wired your load and battery backwards on the switch, which could cause some weirdness.
     
    davidstacoma likes this.
  10. Jul 19, 2020 at 9:03 AM
    #10
    0xDEADBEEF

    0xDEADBEEF Well-Known Member

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    If they're really dim I would start by hooking them directly to the battery to see how bright they should be, and then start going through it one connection at a time to see where the issue is.
     
  11. Jul 19, 2020 at 9:07 AM
    #11
    davidstacoma

    davidstacoma Friendly Curmudgeon

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    Not without a fuse!
     
  12. Jul 19, 2020 at 9:08 AM
    #12
    davidstacoma

    davidstacoma Friendly Curmudgeon

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    If he has lights wired in series they’re really gonna be dim lol. Lights should be wired in parallel if you have more than one in a circuit.
     
  13. Jul 19, 2020 at 9:08 AM
    #13
    0xDEADBEEF

    0xDEADBEEF Well-Known Member

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    Temporarily its not a big deal. I'm talking about just hooking the wires to the battery by hand for a moment, not leaving it that way.


    But otherwise, yes, absolutely with a fuse.
     
  14. Jul 19, 2020 at 9:10 AM
    #14
    davidstacoma

    davidstacoma Friendly Curmudgeon

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    Let’s say he has a defective light that’s shorted- really bad day without a fuse, even temporarily.
     
  15. Jul 19, 2020 at 9:11 AM
    #15
    0xDEADBEEF

    0xDEADBEEF Well-Known Member

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    It might melt some wires if you leave it there. Not sure I would call that a really bad day.
     
  16. Jul 19, 2020 at 9:30 AM
    #16
    davidstacoma

    davidstacoma Friendly Curmudgeon

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    Making big sparks near a lead acid battery can lead to a really bad day if any hydrogen gas is around it, I’ve seen a battery explode just by The small spark connecting up jumper cables to it even though the polarity was correct. I always fan around the battery before making a connection, and that’s why they say to connect the positive first and then connect the negative away from the battery to somewhere on the frame.
     
  17. Jul 19, 2020 at 9:35 AM
    #17
    0xDEADBEEF

    0xDEADBEEF Well-Known Member

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    That is a different situation though. A wet cell battery giving off hydrogen in a jumping situation is a different animal from an AGM battery on a kid's toy.
     
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