leisure battery

Discussion in 'Tech/Mech General' started by paulj, May 25, 2012.

  1. paulj

    paulj Funster

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    I am going to:Wink: add a 2nd leisure battery to my motorhome ,my query is do I need to put an inline fuse on either the positive or negative cable that goes between the 2 batteries and what rating would it need to be any advice would be appreciated
     
  2. hilldweller

    hilldweller Funster Life Member

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    Fuse BOTH ends of positive, so if you get a short anywhere both batteries are protected.

    50A should do.
     
  3. paulj

    paulj Funster

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    Brian, this must seem thick but what do you mean fuse both ends of the positive cable:BigGrin:
     
  4. TheBig1

    TheBig1 Funster Life Member

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    a fuse is needed at the battery end of the supply cable. as this is between 2 batteries fuse both ends as close as possible to the battery
     
  5. Geo

    Geo Trader - Funster

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    Sometimes if batteris are close there is hardly room for a fuse at all I have none on mine because the cable joining the batteries is only 4" long
    However If the batteries are say 3 foot apart a fuse at each end means wherever a fault occurs in that cable a fuse protects it.
    if you only fuse one end. the remaining cable is fed by the other battery and is still live even after the sigle fuse has popped
    Geo
     
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  6. pappajohn

    pappajohn Funster Life Member

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    so, i finally broke into the 'common sense' chain :Wink::thumb:
     
  7. TheDogMan

    TheDogMan Funster

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    I have 2 big batteries double decked with no fuse inbetween them, is it dangerous ????:Eeek:
     
  8. TheDogMan

    TheDogMan Funster

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    Can anyone give me an answer ??
     
  9. jonandshell

    jonandshell Funster

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    You just need to assess if there is a risk of your positive cable shorting to the vehicle chassis, overheating and causing a fire.
    We do have fuses in our habitation battery charging circuit, but only on those parts of the cabling at risk of contacting the chassis.
    For instance, a bared positive cable will not short circuit the battery by touching wood!

    Of course, having your batteries securely located, cables out of harm's way and protected by additional sleeving and grommets minimizes these risks.

    Hope this best answers your question.
     
  10. pappajohn

    pappajohn Funster Life Member

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    If the batteries are close together, which your will be if stacked, with a short interconnecting cable and there's absolutely no chance of trapping/chaffing the cables, then it wont be critical to add fuses.

    i have 4 x 110ah side by side in a purpose built battery tray and all wires are on top of the bank so no fuses.

    usually the two, or more, batteries would be some distance apart due to available space and would need a fuse at both ends of their pos cable
     
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  11. slobadoberbob

    slobadoberbob Read Only Funster

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    i have no fuse.. never have

    I do not have an in line fuse.. never have on any motorhome or RV.

    My two 100 amp batteries are side by side and have a short cable both positive and negative..

    seems a bit over kill to me... I can just imagine trying to fit one:cry:


    Bob:Blush:
     
  12. aba

    aba

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    bob if your batteries are next to each other then there is no need for a fuse as has already been stated however if you had a euro box with its hab battery under the seat and wished to add a second one for example in the rear storage locker then fuses are required to protect the batteries.
     
  13. Reallyretired

    Reallyretired Funster

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    My batteries are a foot or so apart and are fused. My fuses are 300A because of the inverter. If the fuses are too small you may find you are drawing current from one battery while charging another if the fuse blows without you knowing.
    Theoretically your fuses need to be adaquate for the maximum current drawn divided by the number of batteries. IE if you draw 300A from two batteries in parallel, each battery will supply 150A, but if they were fused at 150A the fuses would probably blow quite frequently so have a bit of margin of safety.
    If you're not running a large inverter then the 50A suggested would be fine.:thumb:
     
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