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Proudcanuck's avatar
Proudcanuck
Explorer
Aug 21, 2017

Blown 30 amp battery fuse and no power

Hi all
Having some weird power issues because I decided to try and sell my TT. Here's a run down:

While camping this summer, we moved from a powered site to a no power site. Upon arrival at unpowered site nothing worked at all. We found that the 30 amp inline fuse (the one near the battery on the positive cable) was dead. We replaced it and it blew immediately, replaced with a 25 amp (it was all I had) and blew again. We struggled through three days in the dark, then moved to next stage of the trip with full power.

Everything thankfully worked again (absolutely everything) once we had shore power. We did not replace 30 amp fuse.

We got home and again, nothing worked even when on shore power. Totally dead.
A few days later I tried plugging it in and miraculously everything worked again. We replaced the 30 amp fuse and it didn't blow. Trailer worked well off battery or shore power - I used absolutely everything and no issues.

Trailer sat for five days. I went to put some stuff away today and fuse is again blown and it's all dead. And now when on shore power only outlets work (tv and microwave). Fridge, awning, slide, power stabilizers, lights, radio are all dead. These worked last week on battery and have always worked on shore power.

Tried a different battery and it blows the fuse also. I have crawled underneath checking out all wires for a short and found no issues.

I called local RV service place and got a lot of questions but at the end he said - I have absolutely no idea. Now that nothing works on shore power, I am thinking converter but have never replaced one so I have no real idea.

We can't find a wiring diagram for this TT: 2010 FunFinder X210WBS. Apparently Cruiser RV don't release them.

Thank you in advance for any guidance, tips or ideas. We are at a loss!

20 Replies

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  • Proudcanuck's avatar
    Proudcanuck
    Explorer
    Aug 23, 2017
    Pulled all fuses and put 30A back in near battery. Connected battery at switch and 30A blew.

    Still a short somewhere I guess. RV sercice guy thinks possibly the wire from junction after battery to disconnect switch. It's the only chunk of wire we can't access as it is in the void under the floor.
  • shastagary's avatar
    shastagary
    Explorer
    Aug 22, 2017
    ok searched and it looks like 30 amp 12v fuse is the common size used for the size wire they use going to the battery and it was said that the stock converters rarely put out that much current to the charging circuit anyway. even though yours is a 55 amp converter. i would pull out all your 12v fuses in the converter panel put a good fuse at the battery turn it on and see if it holds if it dose then start putting in fuses back in and see if any make it blow. start with the 2-40 amp reverse polarity fuses first. manual links install and manual
  • Proudcanuck's avatar
    Proudcanuck
    Explorer
    Aug 22, 2017
    WFCO Converter model WF-8955PEC, panel input 30A.

    We crawled around and found no worn wires but wrapped electrical tape on brackets and wires anyway and there did seem to be a short somewhere as this stopped the 30amp fuse from blowing immediately - which it did do before taping stuff. And when connected on Shore power everything was working again ( battery positive wire was disconnected from converter). There are no other circuit protections between fuse after battery and panel.

    So then we were able to check the output (as suggested above) and it was 13.6VDC, just like the panel says.
    We disconnected AC, reconnected +ve wire to converter and pulled battery connect switch and fuse blew.

    Does that sound like converter going kaput? My experience of them going is nil as this is my first and only ever trailer and after seven years, this is first experience of bad power issues and mysteries.

    Thank you all for your suggestions! We feel like we eliminated one or two things tonight. But I did lose the back off an earring. ;)
  • shastagary's avatar
    shastagary
    Explorer
    Aug 21, 2017
    post the model number of your converter if is more than a 35 amp converter that fuse is to small. most use a self resetting circuit breaker at the battery. if your converter is trying to charge at more than 30 amp naturally it will blow that fuse. does sound like the converter could be on the way out you can get replacement power supply boards if that's it main board
  • Proudcanuck's avatar
    Proudcanuck
    Explorer
    Aug 21, 2017
    Thanks everyone for the responses.

    I do have a battery disconnect switch so when it is parked at home the battery is off. So the last time I was in there the battery was 2/3rds. Battery is 2 years old. Normally it holds the charge for a few weeks if disconnected. I don't think we have killed it, but that's why we tried a different one. Although, when we replaced the fuse on the 2nd battery I can't recall if I had disconnected shore power...

    I will spend more time looking for problems on the positive wire, tracing it back to the converter. I found a few small wear areas already on other wires, but not this main one.

    The hunt for a short continues... :h
  • westend's avatar
    westend
    Explorer
    Aug 21, 2017
    It may be that you are allowing the battery to completely discharge. When 120V power is connected, the converter is pushing more than 30 amps into the battery, causing the fuse to blow.

    Allowing all of the parasitic loads to draw from the battery for five days may be enough to completely drain the battery. If you have done this a number of times, there is a good chance that the battery is now bad. I'd suggest to replace the battery and adopt a regimen of disconnecting it when stored between trips. Installing a disconnect switch makes discharging go away, also.

    If the battery fuse is blowing with no 120V connected, you must have a short somewhere in the 12V system. It may be from a failed converter but that is not typical. You should inspect and make sure that the 30 amp battery fuse is the only circuit protection from the battery to the distribution panel.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Aug 21, 2017
    afidel wrote:
    From the symptoms described and assuming no faults you can't see I'm guessing a faulty charging module in the converter, it's putting out enough current to blow the fuse.


    Disconnect battery POS cable at converter.
    Then with AC power measure Converter DC output
    Should be 13.2V DC without any load

    Also check battery cell levels.
    Use a hydrometer and measure each cell specific gravity
    Could be a bad cell
  • afidel's avatar
    afidel
    Explorer II
    Aug 21, 2017
    From the symptoms described and assuming no faults you can't see I'm guessing a faulty charging module in the converter, it's putting out enough current to blow the fuse.
  • Proudcanuck's avatar
    Proudcanuck
    Explorer
    Aug 21, 2017
    It worked without issue for five trips this year, before these issues and has been connected in the same way for seven years (I remove the battery in the winter).
    I have labelled wires and put a label on the battery about connection order (from info I copied off here) so I am very confident it is connected correctly. Boyfriend is a mechanic and he has verified this also.

    The positive wire has the fuse and it is connected to the positive post.
  • ScottG's avatar
    ScottG
    Nomad
    Aug 21, 2017
    Battery hooked up backwards.
    Sometimes the wire colors aren't helpful so you need to verify the neg/ground actually goes to the frame.

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