2nd battery?

Discussion in 'Tech/Mech General' started by Rob, Jan 7, 2015.

  1. Rob

    Rob Read Only Funster

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    Hi all

    This maybe a really daft question but here goes. (still a newbie!!)

    After reading loads on the forum i am going to get a 2nd battery for the MH. Question is what do i need to go with this to connect to 1st battery , charger etc etc?

    Read bits on battery master too, do i need one of these also?

    Thanks in advance

    Rob
     
  2. Wildman

    Wildman Read Only Funster

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    Hi Rob, well first off you are better buying a matched pair of batteries of the same age and condition. They will need to be connected in parallel. i.e. pos to pos and neg to neg. The existing charger will charge both. Keep the connecting cables short and of a decent size.
     
  3. Techno

    Techno Funster Life Member

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  4. Rob

    Rob Read Only Funster

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    What size leads do you suggest ? (not length)

    Cheers

    Rob
     
  5. pappajohn

    pappajohn Funster Life Member

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    Size depends on length.

    If the batteries are next to each other then 4mm will do depending on load.
    If they are a fair distance apart then anything up to 16mm, or possibly bigger depending on the electrical load imposed.
    Unless they are next to each other fit a suitable fuse at EACH end of the positive lead, close to the batteries.
     
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  6. Traveller_HA5_3DOM

    Traveller_HA5_3DOM Read Only Funster

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    If you have an old set of jump leads, they do the job well, you just need some of the large crimp on terminals for the wire and a set of the quick release terminals to attach to the battery. Even the AGM batteries need to breathe so selecting a suitable position to mount it is very important. There are plastic battery boxes available but you will still need to have a clamping arrangement to ensure it does not move. Finally remember that the two wires from your battery can generate enough heat to shoe horses so they will glow red hot in seconds if you short them out to the body work.
     
  7. pappajohn

    pappajohn Funster Life Member

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    Hence the need for a fuse at both ends.
    If the connecting lead shorts to earth anywhere along its length then a single fuse will blow protecting a battery..... Both the other end is still connected to the second live battery and subsequently to earth.
     
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  8. NickNic

    NickNic Funster Life Member

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    Halfords sell battery connection leads. 2 pieces of 35mm cable with a proper crimp lug on each end. Not the cheapest way of getting your result I know but if you don't have crimpers/can't be bothered to mess around probably the easiest way. I used some on our MH because I wasn't happy with what whoever (the dealer) installed the second battery had done. The leads were pretty much the perfect length to join 2 110ah batteries sat side by side.
     
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  9. MikeD

    MikeD Funster

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  10. Traveller_HA5_3DOM

    Traveller_HA5_3DOM Read Only Funster

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    I have always just fused the Live + lead as close to the battery as possible, not sure I understand the need to do the negative earth or the other end of the live. I have actually used the Inverter terminals as my place to join the two batteries together. It saved a great deal of work in dismantling the furniture that My Hobby chose to build the Habitation battery into and having done it once to fit the inverter I thought the Inverter terminals provided the ideal route to link the second AGM battery into the original one.
    Sorry the first post was misleading. The negative wire will not cause problems when it touches the chassis/metal bodywork, it does this anyway. It is for this reason I personally disconnect the Earth first. If you do it the other way round and are in the process of using your spanner on the Positive terminal and touch any of the chassis/metal bodywork whilst winding your spanner round then it will glow red hot in seconds unless you chose to fuse the earth terminals as well. Another reason for the quick release terminals, no spanners needed.
     
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