Leisure batteries (again)

Discussion in 'Motorhome Chat' started by Teuchter, Jul 9, 2016.

  1. Teuchter

    Teuchter Funster

    Nov 4, 2014
    Likes Received:
    Lee on the Solent
    In my last MoHo I wired in an additional leisure battery alongside the existing one in the garage and also wired in a 4 position isolator switch - the same as the one on my boat (off - bat 1 - Bat 2 - both Bat 1&2) - both the mains charger and the 12v distribution/fuse box were alongside the battery all very easy & neat. (not as neat as @Techno did his ;)

    I wish to do the same to my current van but in this van (no garage) the existing battery is under the front passenger seat as is the mains charger (no space for another battery there) The 12v dist/fuse box
    is situated under the fwd facing dinette seat - there is room for one battery there.

    However I have been advised that the existing battery (and charger?) would have to be moved to a position where both batteries can be installed close together.

    Now as a retired Electrical Engineer I can see no electrical requirement for this - sure it means running longer wires between the batteries/ distribution board and finding a suitable site for the isolator (room under dinette seat) and will undoubtedly be more "fiddly" and maybe not so neat but will be electrically no different to having the batteries sit side by side.

    Thoughts anyone please
  2. tonyidle

    tonyidle Funster

    Aug 6, 2013
    Likes Received:
    Kendal, Cumbria
    The only reason to keep them close is to avoid long lengths of heavy cable and extra fuses. Use cable heavy enough to avoid undue volt drop & if there's any chance of earth contact due to chafing fuse the +ve link cable at both ends.
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  3. jonandshell

    jonandshell Funster

    Dec 12, 2010
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    West Norfolk
    Volt drop is negligible in most mains voltage systems. A 25m extension lead will work as well as a 1m flex.
    At 12 volts, it is a different matter. A battery on a split charge system wired with thin cable might only see 13 volts whilst at the other end it will have a 14.3 volts supply from the alternator.
    The result is a slow charging, incompletely charhe'd battery which will sulphate and fail prematurely.
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