Checking RV charger.

Discussion in 'Tech/Mech General' started by Bryan, Oct 25, 2009.

  1. Bryan

    Bryan Read Only Funster

    Jul 19, 2007
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    In my RV I have a converter/charger model 7355.

    How can I check that the charger bit is working?

    The battery voltage is approx. 12.6 volts and this was after they went COMPLETELY dead whilst off hookup and after connecting the hookup it took a bit of messing to get the convertor back on-line (involving jump leads). The battery voltage was then 11-12v and slowly crept up to 12.6

    What I want to do is connect a meter somewhere to make sure that the charger bit o f the converter is actually outputting as it should.

    Where should I measure and what reading should I get?


  2. johnsandywhite

    johnsandywhite Read Only Funster

    Jul 29, 2007
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    :Cool: On my Newmar the Charger actually plugs into a socket in the basement where the line feeds in. If yours is the same? Then disconnect it, measure the voltage, plug it back in and re-check the voltage to see if there is ANY difference? :thumb:
  3. pappajohn

    pappajohn Funster Life Member

    Aug 26, 2007
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    YO11 2BD
    i wasnt aware power supplies/converters had a seperate charger circuit Bryan.

    as far as i know they are just a fixed voltage power supply...13v + which will charge your battery at that voltage cant get a higher battery voltage than the power supply can provide

    thats why they arent very effective at fully charging your batteries.

    a proper 3 stage charger will output upto 14.4v + to boost charge a flat battery then revert to a conventional charger/power supply to maintain the battery.
    the last stage is a maintainance float charge if no current is drawn from the battery.

    so yours is never going to fully charge the batteries anyway.
  4. Knine

    Knine Read Only Funster

    May 19, 2009
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    South West Scotland
    Hi Bryan

    The problem re-starting the system after the battery went very flat is not unusual. The charger sees the low voltage and thinks you might be trying to charge a 6 volt battery (which could be dangerous) so it remains in the off state.

    The fact that once the battery voltage was raised by the jump-start and the charger got going, the charger appears to have raised the battery voltage from 11 volts up to 12.6 volts says that the charger isn't totally dead.

    However, it needs to take the battery up to 13.8 volts to charge it properly.

    You could maybe fit a known good battery to the charger output and see if it sits at 13.8 volts with the charger on (some chargers will not work without a battery fitted - this sounds like one of them). As pappajohn said, 12.6 volts isn't enough to charge your batteries. My guess is that either the charger's current limit circuit is faulty or there is a very loose cable between the charger and the battery or there is a large load on the 12 volt circuit.

    Hope this helps


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