Cable sizing for additional battery

Discussion in 'Tech/Mech General' started by Braunston, Dec 30, 2008.

  1. Braunston

    Braunston Read Only Funster

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    Hi,

    I have been thinking about installing an additional leisure battery and i have been trying to find the cable size that i need as the new battery will be approximately 4-5 metre away from the existing.

    The majority of the new cable will be exposed running along the chassis, can anyone tell me what cable size i need or point me to a site where i may obtain this information, also i would like to install a in-line fuse on the same cable can anyone tell me what size it should be or how to calculate and where i can purchase the in-line fuse holders from.

    any other information that i should take into account would be very helpful

    Thank you

    Braunston
     
  2. scotjimland

    scotjimland Funster Life Member

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    Hi

    AEI Cables have a cable sizing 'wizard'

    AEI Cables - Cable Sizing Wizard - Disclaimer


    JIm


    PS.. you need to register but it only takes a couple of minutes


    PPS

    I used a distance of 5mt with a max load of 50A

    The result is 25 sq mm

    Cable Type6491B-6181XLPE (90°C Single cores)
    Supply voltage (V) 12
    Phase:Direct current
    Cable load (Amps)50
    Cable length (mtrs.)5
    Ambient temperature (c)30
    Average efficiency1.00
    Power factor1.00
    Cable grouping factor1.00
    Temperature correction factor1.00
    No.of circuits:1
    Maximum allowed volt drop (%)5.00
    Selected installation CABLE TRAY FLAT & TOUCHING (IEE Table 4E1A Method F)
    Cable Requirements.
    Cable size (sq.mm):25.00
    Max. current rating over 5 mtrs. 64.86
    Actual voltage drop over 5 mtrs.0.46
    Estimated conductor temperature (c)35.79
    Related Information.
     
    Last edited: Dec 30, 2008
  3. Braunston

    Braunston Read Only Funster

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    Hi, Jim

    Thanks for the link and the calculation, I signed up and ran the calculations and my results are the same as yours.

    However, I am not to sure of the outside diameter of a 25 sq mm cable but i have assumed its similar to a normal ? battery cable, is that correct , if it is, the existing cables that connect the leisure battery are quite small in comparison albeit i don't know the actual size,

    Is it possible to determine the cable size from measuring the outside covering, only if i go for the 25mm and i am correct in my assumed outside diameter size it would look far to big against the existing, hope that makes sense

    any suggestions would be welcome

    Braunston
     
  4. scotjimland

    scotjimland Funster Life Member

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    However, I am not to sure of the outside diameter of a 25 sq mm cable but i have assumed its similar to a normal ? battery cable, is that correct , if it is, the existing cables that connect the leisure battery are quite small in comparison albeit i don't know the actual size,

    That is correct, it's about the same size as the cable used for the engine battery, the existing cable to the leisure battery may be a bit smaller, the constructor would size according to the van's max load and charging current which may be less than 20A but when connecting two or more batteries in parallel the cable should be sized for the max load and length to reduce volt drop .. otherwise they won't charge nor discharge equally.
    If you use the wizard and change the max load to 20A the result is the same.. 25 sq mm

    Is it possible to determine the cable size from measuring the outside covering, only if i go for the 25mm and i am correct in my assumed outside diameter size it would look far to big against the existing, hope that makes sense

    It is possible but not easy to determine, yes it will look bigger than existing cable to the leisure battery

    I would go for 25 sq mm cable and fit a 100A in line battery fuse at both ends of the cable..

    I can't remember the supplier, but you can get battery connectors with built in fuses .. I'll keep Googling


    Jim


    PS

    Found this supplier .. fuses, terminals and cable

    Single core heavy duty electric cable
     
    Last edited: Dec 30, 2008
  5. hilldweller

    hilldweller Funster Life Member

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    You need a fuse at each end - a short in the middle takes out both batteries.


    Brian.
     
  6. scotjimland

    scotjimland Funster Life Member

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    indeed, as I posted... :Wink:
     
  7. olley

    olley Funster

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    Hi for cables try here:VWP - battery cables

    Dealt with them a few times and can recommend their service.

    Olley
     
  8. Dodgey

    Dodgey Funster

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    Thanks you lot, not only do I not need to ask the questions I now have the answers and sources:Smile:

    Simply put, battery dieing and I want to replace with two new and tidy up dodgey wiring etc etc etc!!!!

    Happy new year to all:thumb:
     
  9. hilldweller

    hilldweller Funster Life Member

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    So you did Jim Lad, oh ahrrrrrr, oh ahrrrrrr. Shiver me timbers, I got con fused.



    Brian.
     
  10. scotjimland

    scotjimland Funster Life Member

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    maybe try ... Confused.com :Laughing:
     
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