How thick should the wires be?

Discussion in 'Tech/Mech General' started by irnbru, Oct 18, 2016.

  1. irnbru

    irnbru Funster Life Member

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    Hi all you knowledgeable lot. Alan is wiring up a battery bank of 4 batteries. How thick of diameter should these wires be bearing in mind at a later date I may want to add a 2k inverter....or should it be moms I order in. A bit confused and I like to run things past funsters first.

    Thx
     
  2. andy63

    andy63 Funster

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    35mm square should do..if cable runs are not excessive...:)
     
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  3. TheBig1

    TheBig1 Funster Life Member

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    35mm sq is about right,as using undersized cable will introduce resistance between the batteries
     
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  4. andy63

    andy63 Funster

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    Well I've just had a look on line... they suggest double that ie 70mm square for a 2kw inverter... that''s with load at up to 2 m distance... I'll look again:)
     
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  5. andy63

    andy63 Funster

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    Interesting and confusing read lol

    I have never had an inverter so don't know what the possible surge currents etc can be... the advice on wire size always seems to be follow the manufacturers recommendations. .
    So 35mm square cable is capable of 200A dc.. and I'm sure capabe of a higher surge current so that's what I would use unless told differently..
    Andy.
     
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  6. Gromett

    Gromett Funster

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    I wouldn't want an inverter mounted 2 meters from my battery especially the high power ones. The close to the battery the better.

    Losses in cables are I²R so (current x current) x the resistance. The thinner the cable the cable the higher the resistance, the longer the cable the higher the resistance.

    You can't affect the current used, so you need to reduce the resistance as much as possible by either using bigger cables or shorter lengths or both.
     
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  7. Gromett

    Gromett Funster

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    The other thing to think about when choosing cable size. What type of terminals are on the device. If it is the screw type there might not be a big enough hole to fit the larger cable into. If it is a bolt then some crimp terminals might be too big to fit without touching each other.
     
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  8. Abacist

    Abacist Funster Life Member

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    I used 70mm2 multicore welding cable with crimped and taped ends that were all bolted down to the battery terminals and the same cable to my 1500w inverter that can draw up to 3000w and obviously a big fuse between the batteries and the inverter. The cables between the battery terminals are no more than 1 foot long and the 2 lengths to the inverter is no more than 15 inches. I only have 2 180amp hour batteries linked together which made life a bit easier.
     
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  9. IanF

    IanF Funster

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    Get intelligent ones Sandra thick ones are never much good!
     
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  10. funflair

    funflair Funster Life Member

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    I used 10mm dia or 50mm square on ours but again less than 2 metres from batteries.
    IMG_0881.JPG

    And no I dont have big hands, the 10mm is the copper conductor diameter.

    Martin
     
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  11. andy63

    andy63 Funster

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    That's fair size cable... if it's 10mm diam (is that overall or just the copper core ) it would make it about 78.5mm square...
    Andy
    I should read more closely. .. it's the cu conductor as you said:whistle:
     
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  12. irnbru

    irnbru Funster Life Member

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    Thx I will get Alan to read the thread after dinner.

    What I can tell you is the battery bank is all 4 batteries going under the seat so no long wires (says me) :rolleyes:

    The future inverter would be around there too.
     
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  13. Camping Gaza

    Camping Gaza Funster

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    What about weight issues on just one side of the van, Is this something to consider?
     
  14. irnbru

    irnbru Funster Life Member

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    Shouldn't be as the cooker and fridge are on other side.
     
  15. gus-lopez

    gus-lopez Funster

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    I bought jump leads from Wilko's when I needed some in the UK. 2m in length & some as your photo's. £10 (y)
    home here I use welding cable
     
  16. rupert

    rupert Funster

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    hi and thanks all, for your input. the cable size sandra is talking about is for linking the 4 batteries together. i thought these cables would not need to be as heavy as the load cable to the inverter, as this is shared by the 2 longest cables ,as per the diagram.
    or have i got it all wrong..........again
    batt_new_2.gif

    also i'm intending to box in the bank of batteries to stop them moving around. do they need air to be able to circulate around them to prevent over heating
    thanks alan /rupert
     
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  17. funflair

    funflair Funster Life Member

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    You are right Andy, I was thinking it was 50mm sq but it is good chunky stuff.

    Martin
     
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  18. movan

    movan Funster Life Member

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    Gosh Sandra ... respect woman... I wouldn't have a clue what you are talking about!!! Hope it sorted for you.
     
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  19. andy63

    andy63 Funster

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    Don't worry joy... nor has she..that's Sandra I mean.. @irnbru
    Andy
     
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  20. irnbru

    irnbru Funster Life Member

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    I dont @movan I just want to make sure its done the best way possible and thats where the funsters come in. :)2 heads better than one and all that ...
     
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