RV: No 12v on hookup

Discussion in 'Tech/Mech General' started by Bryan, Dec 2, 2009.

  1. Bryan

    Bryan Read Only Funster

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    Hi,

    RV is on hookup and my understanding is that this means that all the 12v stuff is powered from the converter and the charger will also charge the battery.

    Just gone out to the rig and not only is the battery flat but the 12v systems are not working either. :Sad:

    What (and how) should I start testing?

    Bryan
     
  2. American Dream

    American Dream Read Only Funster

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    Good Luck Bryan.

    Better get some charge in those batteries first or they'll be bricks.

    I assume they have been charging ok throughout the year.

    All 230 volt apps are powered up ok I assume?

    All trips ok on the power board?Power into converter ok?

    What unit is installed in your rig?
     
    Last edited: Dec 2, 2009
  3. Road Runner

    Road Runner Read Only Funster

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    Check you battery leads and terminals.

    I had a similar problem
     
  4. Bryan

    Bryan Read Only Funster

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    All 230v okay.
    All 110v okay
    All trips okay
    Power INTO converter?? How would I know?


    Can't comment on historical as only recently got the RV. However a recent weekend away on hookup and 12v ran off the hookup then ( I think so anyway).
     
  5. American Dream

    American Dream Read Only Funster

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    Or was it residual charge while driving that you were using?

    Any noise at all from the power converter/transformer?

    What unit is it Bryan?
     
  6. Bryan

    Bryan Read Only Funster

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    away for 2 nights and only one 85 amp battery. Lights etc very bright and used blown heating for a short blast with no dimming etc. leads me to believe that 12v coming form hookup/converter.

    Parallax 7355 and it is making a low hum
     
  7. big map

    big map Funster Life Member

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    Hi, Have you checked the 12v isolater switch is on. Most RVs have a small switch which needs to be on for the batteries to charge, this switch must be on before connecting up to 240v. It seems to be that these switches are normally located near the entrance door.

    Mike
     
  8. American Dream

    American Dream Read Only Funster

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    [​IMG]
    So We can assume power ok into it.

    Are you able to measure output? Do You have a Multimeter?

    Any Inline fuses to the batteries?Do you have a fuseboard as in the pic?

    Parallax 7300 series are single-stage output converters providing a single voltage output of 13.8 VDC to the DC system for load and battery charging.

    [​IMG]

    Does this help? http://parallaxpower.com/Dist_Panl/FB Series.pdf

    I thought there was a Relay in the circuit too.Mine's in the engine bay.

    Mike might have the answer there.
     
    Last edited: Dec 2, 2009
  9. Bryan

    Bryan Read Only Funster

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    Right, now I'm just plain stumped :cry:

    According to the parralax troubleshooting guide - my converter works fine.

    I can measure 13.6 volts at the 12v fuse board in the convertor unit.
    I can measure 13.6 volts going into each of the nine 12v circuits (lights, etc)
    I can measure 13.6 volts acorss the battery connections on the fuse board in the unit.

    But, no lights or other 12v circuits work.

    If I put a battery charger on the battery, the lights come on :shout:

    So although the converter is outputting 13.6 volts on all the 12v circuits, it's not getting to the battery and the circuits are coming on - but the battery (such that it is) can get to the 12v circuits.


    Anybody? :cry:
     
  10. hilldweller

    hilldweller Funster Life Member

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    It is my considered opinion that you are an electrical disaster.

    You're back to digging up the wiring again :-(

    You've divined 13.6V so look at the battery end where it might end up and work backwards. See if you can match a wire size/color at the charger end to one at the battery end.

    A pin is useful - you stick it into a cable, hoping it's not 240V and take readings.

    Take your pick:

    1. Fuse.
    2. Broken or eaten wire.
    3. Switch.
    4. Bad connection.

    Fuse is at the top for good reason.
     
  11. Bryan

    Bryan Read Only Funster

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    My main concern at the moment is that even without a battery the 13.6v at the 12v circuit distribution board should be powering the lights etc.

    I'll worry about the battery once the coach circuits are working again :thumb:
     
  12. Geo

    Geo Trader - Funster

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    And that would suggest to me that the break is very close to the board or possibly on it:Eeek:
    Geo
     
  13. Geo

    Geo Trader - Funster

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    Forgot to add and the other Brian may concur just because you get a reading on your tester does not mean the fault does not excist, as the circuit tries to supply a load, ie all the lights it may then fail, but still read good with your meter that has no load as such:thumb:
    Geo
     
  14. Bryan

    Bryan Read Only Funster

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    But if I supply power to the battery, then this feeds back and powers the 12v circuits. Doesn't this imply that there isn't a break?

    My research has discovered that the Parallax system does not have a seperate charger circuit, the battery is simply connected to all the other 12v circuits. It charges with whatever the other 12v circuits are not using.

    Besides all this, the wiring in the RV is such that the Parallax should be powering the 12v circuits even with no battery present.

    Here's some measurements... :Smile:

    Using a multimeter I have discovered the following:

    Removing both 30amp polarity fuses and testing between the converter input to the fuse board (blue wire) and the negative connection gives 13.6 volt.
    Testing across the battery connections at the converter fuse board gives 13.6 volt
    Replacing the polarity fuses and testing from any of the 12v circuits positve (just below fuse) and the battery negative connection on the fuse board gives 13.6v.

    But NO 12v circuit works.

    Now, despite having a reading across the battery connections on the converter fuse board of 13.6 volt, the actual reading at the battery is 9 volt. Now I know that this means that the battery is no good, I can't understand why I get the differnce in readings.

    Also, and perhaps crucially, if I connect an external battery charger to the battery then the 12v circuits in the coach come on...

    And in case it helps, with the polarity fuses removed, the reading at the fuse board across the battery connections is the same as at the batteries.

    I am really confused as all the information I can find says that the Parallax should be powering the lights etc even if there is no battery, and I do read 13.6 volt at the 12v circuit fuse but get no power anywhere.


    :shout:
     
  15. jhorsf

    jhorsf Read Only Funster

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    Bryan it may help if you said where you were then maybe a funster who is a spark is near and could come to your aid? I am just thinking out aloud.
     
  16. Geo

    Geo Trader - Funster

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    Check all earth conections around the board and batteries:thumb:
    Im convinced sothing is loose, or a bad but looks good conection
    Given that your problem started before you went away,fixd its self when arrived on site and broke again by the time you got home or next checked:Doh:
    Dont try and make sense of faulty electrics it is a law unto its self
    Just fix it:thumb:
    Geo
     
  17. American Dream

    American Dream Read Only Funster

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    So....Is your battery Knackered?....Think simple and go for the obvious first.....

    As a species we tend to over look the obvious and over complicate issues?

    It may have taken out a fuse in the process or the electronics of the Parallax may sense an overload due to bad battery condition and shut down....
     
    Last edited: Dec 3, 2009
  18. hilldweller

    hilldweller Funster Life Member

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    That is one thing I forgot to say - that looks like a PCB and not only are the soldered joints dodgy if anyone has ever put in an oversized fuse then the PCB track will act as a fuse instead. I'd be looking underneath it if not too difficult.
     
  19. Bryan

    Bryan Read Only Funster

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    I've had it in bits :cry:

    Everything seems fine. Nice clean tight connections and expected voltages in expected places.

    Just nothing working...

    110v to the converter? Check
    13.6v from the converter to the 12v fuse board? Check
    13.6 volt after the fuse on the fuseboard? Check

    As I say, not bothered about the battery really, the parallax should power the 12v stuff even without a battery present. If I get that sorted, a replacement battery should charge.



    Battery is dead I reckon, but that is not a concern. See above :Smile:
     
  20. Bryan

    Bryan Read Only Funster

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    Looked behind, not really a lot there, just the back of fuse holders...

    See last reply to Geo...





    BTW...

    Proper doin' me 'ead in, is this :Angry:
     
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