Is Wire Length Important?

Discussion in 'Solar Power' started by Yorick, Jul 16, 2015.

  1. Yorick

    Yorick Funster

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    I've just bought a folding 100w panel but the lead is only 2.5 metres long. It barely reaches the battery from left side, but no chance from right side.

    I think I read somewhere that if the lead is too long, then it loses volts/amps or whatever ;)

    Put me out of my misery please :)
     
  2. pappajohn

    pappajohn Funster Life Member

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    Correct.....volt drop over a long distance.

    Just extend the leads using 4mm to 6mm flexible cable.
     
  3. Yorick

    Yorick Funster

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    Sorry, that's a bit ambigous to me....

    The wire it comes with is 4mm (if you measure the outside). So should I extend it with 6mm ?
     
  4. LaMB

    LaMB

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  5. pappajohn

    pappajohn Funster Life Member

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    If it comes with 4mm then use the same.

    Volt drop only really becomes a real issue if the cable run is very long....batteries at front of van and contoller at the back.
     
  6. pappajohn

    pappajohn Funster Life Member

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    Just realised you dont mention a charge controller........100watt panel will cook your battery without one.
    the controller fits between battery and panel and regulates the charge current to prevent overcharging and boiling.

    DONT connect directly to your battery.
     
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  7. Wildman

    Wildman

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  8. LaMB

    LaMB

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    I don't think the voltage drop on a couple of metres would be significant though for the OP to worry about, and I rather think the OP has measured the cable diameter including the insulation.
     
  9. Minxy Girl

    Minxy Girl Funster Life Member

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    Maybe I'm missing something but ... it's a folding PORTABLE panel ... so move it nearer to where the battery is!
     
  10. LaMB

    LaMB

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    Yes I think you are. If the OP moves it nearer the battery it may then be in the shade!
     
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  11. Wildman

    Wildman

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    for safeties sake all solar cables should be at least 4mm² but please yourselves. When light levels are low ANY loss is unacceptable if it can be avoided
     
  12. LaMB

    LaMB

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    ?
     
  13. Wildman

    Wildman

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    losses are in the form of heat, too small a cable and there is potential for a fire, especially on a cable exposed to the sun and already heating it up. Better safe than sorry.
     
  14. LaMB

    LaMB

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    100W at 12v = less than 9amps so 20 amp cable would be overkill anyway!
     
  15. pappajohn

    pappajohn Funster Life Member

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    The cable the panel comes with is just adequate.

    8amps at 12v with a 3% volt drop over 2.5mtrs = 2.5mmsq cable

    Same parameters over 4mtrs = 4mmsq

    Same parameters over 5mtrs = 6mmsq

    Same parameters over 10mtrs =16mmsq
     
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  16. tonka

    tonka Funster Life Member

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    LOL.... What a fuss.. Here is the Funster answer..

    Yea shove some cable on and get on with it..
    It will still work ......

    SORTED.........

    :)
     
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  17. Yorick

    Yorick Funster

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    Yes, it comes with a controller :)
     
  18. Yorick

    Yorick Funster

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    yes, it is 4mm diameter. Is that big enough for a 4m long cable ?
     
  19. Yorick

    Yorick Funster

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    I can't coz the cable is too short ;)

    Only 2.5m and leisure batteries are inside the van and half the cable is in the van :)
     
  20. DavidG58

    DavidG58 Funster

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    I spent ages thinking size meant diameter, it refers to cross sectional area, so actually quite small dia which will include the outer cover :)
     
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