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Polarity Switching

Discussion in 'General Electronics Discussion' started by MayaRefugee, Oct 20, 2020.

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  1. MayaRefugee

    MayaRefugee

    5
    1
    Oct 20, 2020
    Hey Guys,

    I have a string of solar LED fairy lights and the solar panels weathered and needed replacing. I acquired some new solar panels but they only light up half of the LED's on the string. When I swap the wires the other half of the LED's light up that don't light up in the first position.

    The strings of lights are on decorative ball frames which took some work to arrange so replacing the whole lot is not something I want to do as I would have to redo the whole thing.

    What I'm wondering is is there a circuit or something similar that I could wire up that would reverse the polarity of the wires at a rate that would be so quick that it looks like all the LED's are lighting up at the same time. The way it is at the moment only half the LED's have the right polarity, if I can get something to swap the polarities quick enough I think I might be able to solve my problem.

    Thanks in advance for you help.
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,544
    2,349
    Nov 17, 2011
    This sounds like you have 1/2 of the LEDs in opposite polarity to the other half so the whole setup can be operated by AC instead of DC. You will need a kind of DC/AC converter, I think.
    If the setup worked with the old panels, you will have had such an inverter in place, otherwise you'd have seen the same effect.
    What are the specifications of the LEDs and the solar panels?
    Can you show us a wiring diagram of the old setup and the new setup? Surely there is a difference which will point to a possible solution.
     
  3. MayaRefugee

    MayaRefugee

    5
    1
    Oct 20, 2020
    Thanks for the reply,

    I don't know the specs of the strings, the old panels had two wires coming out of them and the replacement panels have three, on the board of the new panels there's L1, L2 and a positive rail. The old ones just had a positive and a negative. The only place selling replacement panels I could find only had panels with the three wires.

    The old panels were a mix of single AA battery and double AA battery, the new panels just have a single weird sized battery.

    As I said when I hook two of the three wires from the new panels up to the two wires coming off the string I get half the lights lighting up, when I reverse the wires the other half light up - my thinking is if I can get these to swap very quickly all of them might appear to be on at the same time.

    EDIT: The battery in the new panels is under 5 volts, I can't remember exactly I'm sorry.
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    10,544
    2,349
    Nov 17, 2011
    Do you have a datasheet or a link to same for the new panels?
     
  5. MayaRefugee

    MayaRefugee

    5
    1
    Oct 20, 2020
    The only info I could find is this info from off the box they came in:

    Input: 6V, 180MA
    Output: 31V, 65MA
    Battery: 3.7V, 1500MA

    Sorry but this is all I have.
     
  6. ratstar

    ratstar

    263
    11
    Aug 20, 2018
    Does it have 3 wires? maybe the center is the ground, but of course you would have tried that right?
     
  7. Harald Kapp

    Harald Kapp Moderator Moderator

    10,544
    2,349
    Nov 17, 2011
    Solar panels with an input and a battery?
     
  8. MayaRefugee

    MayaRefugee

    5
    1
    Oct 20, 2020
    I've tried all combinations of wires, no matter what I try only half the LED's light up.

    Harald, I think the input they are talking about is the output of the solar panel which charges the battery, I'm not sure though.
     
    ratstar likes this.
  9. Alec_t

    Alec_t

    2,902
    784
    Jul 7, 2015
    The '31V' rating indicates the presence of a boost converter. If that 31V is AC then that explains how all LEDs could light.
     
  10. Harald Kapp

    Harald Kapp Moderator Moderator

    10,544
    2,349
    Nov 17, 2011
    This combination makes no sense:
    Input power is 6 V × 180 mA (note: small "m" - a capital "M" indicates Mega :rolleyes:) -> 1.08 W
    Output power is 31 V × 65 mA --> 2.015 W
    Output power is twice the input power - you've found the perpetuum mobile ;)
    Did you buy these online? Then maybe the website has more info?

    I totally agree, but that is inconsistent as only 1/2 of the LEDs work with the new panels.
    @MayaRefugee : Or is this the data from the old panels? You see me confused. Please explain in more detail which parts are old and which parts are new and how you connect them.
     
  11. MayaRefugee

    MayaRefugee

    5
    1
    Oct 20, 2020
    The box just has a sticker from the seller stating the above info, I brought them off ebay - it all seems like a rebranding of something they source from somewhere else, there is no branding on the actual panels.The info I stated is relevant to the replacement panels, I have no info on the old panels.

    Basically the old panels had two wires coming off the board and the new ones have three. The new panels light up the LED's but only half of them light up, when I flip the wires the other half light up. I'm tipping there was some kind of switcher on the old board to account for LED's that aren't all wired up in the same way i.e. ones where the positive and negative are back to front vice versa. The new panels will only light up half the lights no matter what configuration of wires I use, the only thing I can get happening is the unlit ones coming on when I reverse the wires. I'm hoping to discover something that effectively reverses the wires so quickly that it looks like all the lights are on together.
     
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