Wiring 2nd Habitation Battery

Discussion in 'Tech/Mech General' started by jtp890, Jun 18, 2015.

  1. jtp890

    jtp890 Funster

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    Help needed
    Looking to fit 2 new 100ah batteries
    Original sits under passenger seat, 2nd will be located 5m to rear of van.
    2no 80mm sq cables draw from each terminal, connected to 40 & 20 amp fuses.
    What size cable do I use to connect 2nd battery?
    Help greatly appreciated
     
  2. Moodybrook

    Moodybrook Funster

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    Hmm, are you sure there isn't room for two batts side by side, The interconnecting cable for 5m, to minimise voltage loss would be huge.

    I'd be getting a saw out to make room !!

    I'll leave this to someone who has had experience of doing what you want to do, this willbump you back to the top (y) ;)
     
  3. pappajohn

    pappajohn Funster Life Member

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    80mmsq cable...that has to be a typo.
    Starter motor cable is usually 16sqmm and I reckon it should read 8mmSq.

    You will need 16mmsq for a 20 amp load and 25mmsq for a 40 amp load.
    Both 5 meter in length with a 3% volt drop
     
  4. jtp890

    jtp890 Funster

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    Cable size was calculated from 5mm dial giving 80mm sq
     
  5. Martin OSullivan

    Martin OSullivan Read Only Funster

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    Any room in the engine bay or under the other seat??
     
  6. jtp890

    jtp890 Funster

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    Nope
    Van is a dethleffs on Renault master, drivers seat has control box, dinette seat houses water tank.
    Could maybe reduce by a meter if fix in wardrobe
     
  7. jonandshell

    jonandshell Funster

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    25mm sq for the positive to minimise volt drop during alternator charging.
    Take the negative through the floor and direct to chassis using 25mm sq.
    That's what I would do!

    My van uses 50mm cable for a 6m run carrying up to 80 amps during charging. The volt drop is about 0.1 volts at that sort of current.
     
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  8. Dazzlin

    Dazzlin Funster Life Member

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    Hi Jim
    I put our 2nd battery behind the passenger seat.
    Made a wood base so it sits on the seat bolts and secured with a battery strap screwed to the seat box. Takes a little leg room up but not been a problem.
    Means the leads are 18" long!!!
    Hope this helps.
    Hope to see your van some time.
    Darren
     
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  9. jtp890

    jtp890 Funster

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    Thanks Darren
    Aiming to fit adjacent wine rack tight up to passenger door buttress
    Should keep cable length below 1m
    Thanks to everyone for help
     
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