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20 amp fuse

I was wondering if a bad battery could cause you to blow out your 20 amp fuse .I have never had this happen before

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    Tabaz Tabaz Member Posts: 2,356
    If you're referring to the in-line blade fuse at the battery, it should be 30 amp.  See "fuses for newbies." My dealer had a 20 amp in there which kept blowing until I replaced it with the correct 30 amp.
    2016 Outback 320 with a 2010 Ford Expedition.
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    PhotomomPhotomom Member Posts: 2,217
    Me too - needs to be 30a.
    John and Henrietta, Late 2016 T@B S Max in Western New York
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    JandJ92010JandJ92010 Member Posts: 304
    Mine camp with a 20 also. Every time I pulled it, it would pop, replaced with a 30. No problem since.
    The HobbiT@B, 2015-L, towed by a2014 RAM C/V
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    RollingLagrimaRollingLagrima Member Posts: 435
    Mine came with a 10amp from the dealer. You can guess how that worked out...
    Sally, "PlaT@Bus" 2016 T@B Sofitel Maxx-S (plata=silver; SP), previously Little Guy 2014 Silver Shadow LE, TV -- 2013 Chevy Avalanche + two hounds.
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    clkellerclkeller Member Posts: 46
    Thank you so much for the information I will replace it with a 30 amp fuse 
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    clkellerclkeller Member Posts: 46
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    RollingLagrimaRollingLagrima Member Posts: 435
    As a follow-up warm fuzzy, I have had no issues since swapping out to a 30amp. :)
    Sally, "PlaT@Bus" 2016 T@B Sofitel Maxx-S (plata=silver; SP), previously Little Guy 2014 Silver Shadow LE, TV -- 2013 Chevy Avalanche + two hounds.
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    ScottGScottG Administrator Posts: 5,421
    clkeller said:
    I was wondering if a bad battery could cause you to blow out your 20 amp fuse .I have never had this happen before
    Fuses blow when the current (amps) flowing through the line exceeds their capacity. Since the current depends on the load from devices, it seems unlikely a bad battery would cause a fuse to blow.
    2015 T@B S

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    clkellerclkeller Member Posts: 46
    Ok so what might have caused this to happen any ideas
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    VernaVerna Member Posts: 6,878
    clkeller said:
    Ok so what might have caused this to happen any ideas
    @clkeller, unless you have a short, it is unlikely you'll ever find the exact cause.  
    Verna, Columbus, IN
    2021 T@B 320S  Boondock “The T@B”
    Towed by a white 2019 Ford F-150 4x4 Supercab, 3.5L V6 Ecoboost “The Truck”
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    marknjudymarknjudy Member Posts: 378

    I hope I'm answering what you are asking. So the amount of current flowing through the battery fuse is equal to the sum of all the current draws of anything plugged in and turned on that receives its power from the battery - entertainment system, television, refrigerator in DC mode. If you had nothing turned on, it's conceivable that a 5 amp fuse wouldn't blow - not until you started turning things on that had more and more current draw. A 30 amp fuse is used because it was determined that if everything that can run on DC power was turned on and running, it would not exceed 30 amps. If it does, pop goes the fuse.

    So, if it didn't use to blow the fuse before, it's important to know whether it blows now as soon as you put a new fuse in; or if it's only when using a certain device. If it blows immediately, you've got a direct short somewhere - and THAT'S a whole bucket of worms to find and may take someone with knowledge of the trailer's wiring. But if it doesn't blow immediately, systematically start turning on DC devices until the fuse pops and you'll have your culprit. Alternately, if you have access to an ammeter, you can insert it in series with the hot line coming from the battery and look for an overcurrent condition.

    I hope this helps and is what you were asking.


    Mark - 2016 T@b Max S (Silver/Red), 2012 F-150
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    ScottGScottG Administrator Posts: 5,421
    clkeller, what were you doing (if anything) when the fuse blew? Along the lines of what marknjudy said, if you were running several DC devices at once, it's possible you could exceed 20A.

    Also, just to clarify, am I correct that this was the fuse at the battery, as opposed to at the converter?
    2015 T@B S

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    marknjudymarknjudy Member Posts: 378

    Also, don't discount have had something plugged into the cigarette lighter socket underneath the front cabinet or anywhere else you may have one.

    And another thing I just thought of: if the fuse blows even when nothing is turned on, it may not be a wiring problem. This like the entertainment center, the television and at least one other thing that I can't think of maybe the CO2 detector are always on in at least a standby mode.

    Mark - 2016 T@b Max S (Silver/Red), 2012 F-150
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    marknjudymarknjudy Member Posts: 378
    Let us know what you find.
    Mark - 2016 T@b Max S (Silver/Red), 2012 F-150
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    clkellerclkeller Member Posts: 46
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    wizard1880wizard1880 Member Posts: 442
    If your T@b's battery is very low, let's say 12.1 or under, just connecting the 7-pin to your tow vehicle can blow the fuse.  The battery is basically a sponge at this point and will take any charge it can get!

    If you have a 30a, you'll be fine.
    T@@bulous
    2014 T@B CS Maxx
    TV: 2015 Audi Q7 3.0 V6 TDI (diesel)
    Martha Lake, WA
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    Michigan_MikeMichigan_Mike Member Posts: 2,861
    clkeller said:
    I was wondering if a bad battery could cause you to blow out your 20 amp fuse .I have never had this happen before
    As noted above it could be from running lets say the Fantastic vent fan, TV/DVD player and pump together (as an example) or anything that would cause an amperage on the line that exceeds the rated 20 amp fuse.  A momentary voltage spike, a loose connection (that creates heating) or possibly a short circuit (bare wire rubbing against a ground) would cause something similar to happen.  You will probably be fine now after having upgraded to the 30 amp fuse.  
    Mike - Elmira, Mi / 2019 T@B 400 / 2021 Chevy Silverado LTZ
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