2nd leisure battery

Discussion in 'The Beginner' started by gazzeroo, Oct 13, 2014.

  1. gazzeroo

    gazzeroo Funster

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    Can anyone advise on how to safely connect a second leisure battery, My current one charges from the engine and when I`m hooked up. Also, I know it a piece of string thing, but how much use would you get from 2 110ah batteries, using lights and fridge only.
     
  2. sdc77

    sdc77 Funster

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    For connection... Pos to pos and neg to neg...
    Take the positive connections from one battery and the negative connections from the other.
     
  3. funflair

    funflair Funster Life Member

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    Hi gazzeroo

    First thing is that it's recommended to only connect batteries of the same size and age and certainly the same type so don't pair a Gel with standard lead acid for example.
    You need a suitable and safe place for the second battery which includes ventilation if it a vented lead acid, then you connect neg to neg and positive to positive with suitably sized cables and fuse, the size of the cables will partly depend on the use you are going to give the batteries, a big inverter would need a bigger cables than just lights and pump.
    Typically if you fit a second battery the same size you will double the capacity that you currently have, so you will double the time available off hook up.

    Martin
     
  4. gazzeroo

    gazzeroo Funster

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    thanks for that! I sort of got that bit, I was thinking more like what type of wiring, whether I need a fuse between the batteries, will the charger charge both batteries automatically or do you have to switch them?
     
  5. pappajohn

    pappajohn Funster Life Member

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    The charger will 'see' only one large battery...not two smaller ones linked together so yes it charges both at once, but will take twice as long to charge.
    fuses....yes, definately.
    unless both batteries are next to each other then put a fuse at both ends of the positive lead.that way if the link wire should short to earth both fuses will blow completely isolating both batteries.
    if only one fuse is used the wire will still be shorted on the end with no fuse with a real possibility of fire or exploding battery.
    30amp fuses should surfice if you dont use an inverter.
    wire size......too small and it will overheat under higher loads so buy at least 6mm/sq if the batteries are close together.......35mm/sq if they are a couple of meters or more apart.
     
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  6. gazzeroo

    gazzeroo Funster

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    Thanks that's very helpful
     
  7. jockaneezer

    jockaneezer Funster

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    Check your charger is up to charging the combined amperage of two batteries, some vans fitted with EBox panels can burn out the charging circuit.
     
  8. iceni

    iceni Read Only Funster

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    The latest thinking (Caravan Council) is that fuses should not be used in battery compartments so put the fuse is a place that’s out of the actual battery compartment. The reason is that the fuse may blow when the battery is being heavily charged and giving off hydrogen gas. This is explosive and so the fuse may set off an explosion.
    When you think about it banks of batteries in a fork trucks are connected together and don’t have fuses between them. They are not really needed between batteries only between batteries and appliances to protect the appliance
     
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  9. scotjimland

    scotjimland Funster Life Member

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    small correction..

    fuses are fitted to protect the cable from overload or a short to earth .. .. not the appliances ..


    Some useful information and diagrams on battery connecting

    http://www.motts.org/second leisiure battery.htm

    [​IMG]

    [​IMG]
     
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  10. gazzeroo

    gazzeroo Funster

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    Brilliant, Thanks
     
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