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Drought_Buster's avatar
Drought_Buster
Explorer
May 25, 2014

SOS! Battery died while hooked to shore power.

After a long winter, I hooked the Montana Fifth Wheel to shore power and reinstalled the battery that was stored in my basement. I went in and had power to the outlets, microwave... and all the lights came on bright. However, refrigerator, AC and stereo had no power. I quickly realized I had made a rookie mistake and hooked the battery up wrong (positive cable to negative terminal and vice versa). I switched the cables, tried it again and everything came on just fine (12 volt lights, outlets worked, microwave on, AC came on...). Waited a few days and put the slides out just fine. Five days later I went in and there is absolutely no battery power at all despite being hooked to shore power the whole time. Lights came on very dim for a few seconds and slowly faded out. So I assume I did something to the inverter when I hooked the battery up wrong. But if so, why did the lights come on bright both when the battery was hooked up wrong and once I turned it around? Seems like if I fried the inverter, the 12 volt lights would not work once I changed the cables around. Anyway, electrical is not my thing. Anyone have any clue what I did to end up like this?

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  • BobsYourUncle's avatar
    BobsYourUncle
    Nomad
    May 25, 2014
    pianotuna wrote:
    Hi,

    Check the reverse polarity fuses on the converter.


    What Don said. :)

    Likely 2 of them in there, and could be inline fuses in the wires that only a mouse can find and see! They will likely be close to the converter.
  • RoyB's avatar
    RoyB
    Explorer II
    May 25, 2014
    On a typical Power Distribution Panel you will find the REVERSE POLARITY fuses located on the 12VDC side of the panel usually off to them self. These will be be two high amperage ATC type fuse. You may also have a 3rd IN-LINE fuse blow which may be installed real close to the battery terminals. Some of the newer trailers use a 12VDC AUTO-RESET Breaker here.

    The REVERSE POLARITY fuses are located almost in the center of this google search photo of a typical power distribution panel... (Two 40AMP ATC fuses shown here)



    Make sure the battery is back to the correct connections before changing fuses otherwise it will just blow them again. I always look at the battery case for the word 'NEG' or the symbol '-' and make sure this is the battery terminal going to the trailer frame ground. If your trailer is using RED and BLACK battery cables this will be the BLACK CABLE... If you are using BLACK and WHITE cables then this will be the WHITE CABLE. Best thing is to hand trace them out regardless of the wire color...

    Roy Ken
  • Drought_Buster's avatar
    Drought_Buster
    Explorer
    May 25, 2014
    The humming or fan noise is coming from behind the panal box (with the breakers and fuses. There are four screws holding the panel box in. Do I just remove those and take the whole electrical panel box out to get to the converter? Do you know what a reverse polarity fuse looks lie?
  • hmknightnc's avatar
    hmknightnc
    Explorer
    May 25, 2014
    Drought Buster wrote:
    Mini breakthrough. I flipped the breaker labeled "converter" and heard what sounded like a fan come on. It stayed on for about three seconds then went off. I flipped the breaker, waiter thirty seconds, flipped the breaker back on and, again, a fan or hum for three seconds and it went off. So it sounds like it wants to start but can't for some reason. The problem is I can't find the dumb converter to take a look at it.


    It's probably behind a panel right below those breakers. Find it and replace it, also check those reverse polarity fusses since you hooked the batteries wrong
  • sch911's avatar
    sch911
    Explorer
    May 25, 2014
    pianotuna wrote:
    Hi,

    Check the reverse polarity fuses on the converter.


    X2
  • Drought_Buster's avatar
    Drought_Buster
    Explorer
    May 25, 2014
    Mini breakthrough. I flipped the breaker labeled "converter" and heard what sounded like a fan come on. It stayed on for about three seconds then went off. I flipped the breaker, waiter thirty seconds, flipped the breaker back on and, again, a fan or hum for three seconds and it went off. So it sounds like it wants to start but can't for some reason. The problem is I can't find the dumb converter to take a look at it.
  • newman_fulltime's avatar
    newman_fulltime
    Explorer II
    May 25, 2014
    OK sou ends like you have a wfco converter if so the front panel comes off by unscrewing the screws in the top corners .
    Try hooking a battery charger to the batt if everything works sounds like you have a fried converter
  • Drought_Buster's avatar
    Drought_Buster
    Explorer
    May 25, 2014
    Yeah, the battery disconnect is in the right position. When it is off, there is absolutely no power to 12 volt. This is the first thing I checked to figure out that the battery wis wired wrong. When I switched that all the 12 volt went out. Put it back and the lights came back on. I do not hear a hum, but do not recall ever hearing one. I can't seem to locate the inverter. I did flip the breaker labeled "converter", but nothing happened. None of the little lights that come on to indicate a blown fuse is lit. I changed the fuses that are in the lines inside the battery compartment even though I have no idea what they go to. If I can find the inverter, I am hoping it has fuses on it that I can try changing. I have a Montana High Country DBRS. Any idea where my inverter is??
  • newman_fulltime's avatar
    newman_fulltime
    Explorer II
    May 25, 2014
    Is your battery disconnect on do you here the fan run on your converter disconnect the battery kill power turn it back on and see if it starts working check the fuses breakers

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