Camping 12v Project

Discussion in 'The Projects Forum' started by howzat, Jul 4, 2008.

  1. howzat

    Thread Starter New Member

    Jul 4, 2008
    3
    0
    Hi,
    For longer term tent camping purposes,
    I have just bought a 200amp battery to be charged by a 30amp marine charger (@ stated 80% efficientcy) powered by yamaha 1000 generator.

    I am wondering if I need to (negatively) earth the battery (or battery bank) to the ground?


    Also would it be a problem charging the battery with everything else connected at the same time?

    Having seven kids, I believe a twelve volt system is pretty safe except possible fire start. I will also run an inverter for some ac devices.

    Thanks for your assistance.
    Jonathan
     
  2. RmACK

    Active Member

    Nov 23, 2007
    54
    0
    Jaycar have an excellent primer on inverters that covers the safety issues regarding earthing of the mains side of the inverter & how this affects the earthing of the battery. See here
    With regard to fire safety, at 12V you will have very high currents flowing so ensure your cabling is adequate (don't want them melting!). The main danger with batteries even of just 12V is their extremely low internal resistance. This means that if short circuited, the fault current can be enormous, over 1000Amps from a 200amp hour batter! So you should ensure that it is not possible to e.g. drop a spanner across the terminals. There should be a fuse in line with the battery AT the battery as a final resort if the worst happens. Smaller loads should have their own smaller fuses depending on your installation.

    Check if the charger has overcurrent protection. I think this is the only possible issue with charging/using the batteries at once. Still it would just look like a really dead battery to the charger so I don't think it would be an issue. Any one else want to comment??
     
  3. Cornelius

    Member

    Mar 17, 2008
    19
    0
    Depending on your weatherconditions at the campingsite, and your budget, you should really consider some solar panels, and maybe an windgenerator.

    3 solar panels at 120W each would probably cover your needs on a sunny day, without the need to start the genny... ;)

    And conservation is important. Turn off everyting you don't use; even a small lightbulb could drain your battery in a couple of days...
     
  4. howzat

    Thread Starter New Member

    Jul 4, 2008
    3
    0
    Thanks Rmack for the link to Jaycar on inverters. I also saw that they have some robust 75 and 100 amp circuit breakers, for the terminal frizzer scenario I assume. I have a 15 amp c/breaker as I start to build, just running a 1amp light so far. But like you suggest, a c/break near the terminals might be the way to go, though for me 30-50 amp c/b would be plenty at this stage.

    I wonder if it is prudent to run an earthing cable to the ground from the negative terminal? There is no drain/damage on the battery in this?

    Cornelius I am considering a wind generator as these seem pretty cost effective. Can't afford the solar at this stage.
     
  5. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    I don't have a firm stand on this, but I don't think it would be necessary to ground it. Having said that, grounding does provide some safety from high voltage, but if there is a ground wire from the generator to the charger then most of the concerns have been met.
     
  6. Søren

    Senior Member

    Sep 2, 2006
    472
    28
    Hi,

    I beg to differ.
    Touching both leads, an earth/ground connection won't help and touching only the "phase", the earth/ground connection will be the discharge path making it dangerous!

    In short... Don't use a ground connection.
     
  7. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    Actually I said ground wire, not ground. Something to reference the case to.
     
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