Second battery location?

Discussion in 'Motorhome Chat' started by Wollow007, May 12, 2012.

  1. Wollow007


    Dec 17, 2011
    Hi Guy's

    I've started the installation of the solar panels etc. installing a Victron system which I have to say is top quality.

    I have installed the charge controller, monitor and a Victon battery monitor, shunt etc etc, wire coming out of my ears lol, taken my time and installed it properly though.

    I currently have a 75ah battery under the drivers seat (Swift Sundance 630G 2004). I want to change this battery and add another. I am aware that I need to keep them the same size amp hour wise and have been advised that the passenger seat would be an ideal place to install, however there is plenty of space under the rear seats (storage area).

    So my question is should I install under the front passenger seat or rear seat.

    Also is it correct to keep the amp hour rating the same for both batteries?

    I have noticed that the wiring running from the main leasure battery is only small, circa 4mm and currents has a 20amp fuse (I believe), I'm going to downrate the fuse to a 10 or 15amp as the cable rating will only be around 17amps. The solar panels will only kick around 9 amps so the cabling I have installed (6mm from a new fuse board to the batteries, 4mm connecting to the charge controller to the fuse board, which is around 8 inches from the fuse board) I will also rate the fuses at 10-15amps.

    Any advice will be helpful ;)
  2. TheBig1

    TheBig1 Funster Life Member

    Nov 27, 2011
    you need to bear in mind that the longer the cable run to the batteries (and from battery to accessory rtc) should be kept as short as is practically possible. this is due to voltage drop over the length of the wire and any connections in it. You will therefore be wasting a percentage of the solar panel output

    positioning the batteries at the rear of the van would mean that they are at the furthest point from the alternator to charge as well
  3. Rayb182

    Rayb182 Funster Life Member

    Nov 13, 2009
    Great Bentley
    IMO I would try keep the weight forward, towards the front wheels,
  4. pappajohn

    pappajohn Funster Life Member

    Aug 26, 2007
    YO11 2BD
    parallel connected batteries can be of any mixed size......90ah plus 75ah plus 110ah.

    this will make one big 275ah 12v battery in three separate casings but the charger only sees it as one battery.

    a battery will only accept its max capacity but the higher rated ones will continue to charge until they are all full.

    picture it like this.......

    a water jug (75ah battery) in a washing up bowl (90ah) in a sink (110ah).
    start by filling the jug, when full it will overflow into the bowl, when that is full it will overflow into the sink until that is also full....but the first two will not fill any more than full.

    age and condition WILL make a difference though
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  5. darklord


    Apr 28, 2011
    I put another one on our Sundance, under the passenger seat. Undo the four torx drives, lift the seat off, then there is plenty of room to work. The wires can be sleeved and slip under the "step" bit from the hab area just level with the back of the seats. Worked well enough for me.
    Its always worht doing a "measure up" as well, see how many days you can go on, one..then two batteries, then youll know if you want toadd more in tne could use the garage for this, running a feed direct from the charger to anothet bank.

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