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ian_c's avatar
ian_c
Explorer
Sep 29, 2015

30 amp in-line fuse continually blows

Boy do I need some help! Every time I try to extend the landing gear on our 5th wheel when hitching or unhitching the 30 amp inline fuse blows after a few seconds.

We had this problem a few years ago, were told that our house batteries weren't charged and, after charging them at a gas station everything worked well. For a time.

On our current trip all was well until last week in Zion. We'd been on the road for about 5 weeks. All of a sudden we started blowing fuses again. The "charge" indicator on the rig panel read "fully charged" but we could not raise the trailer.
I finally caved in and bought a new pair of 6v Deep Cycle Interstate GC2's in Kanab.

This morning we hitched up without problem but when trying to raise the trailer to unhitch the fuse blew after 20 seconds. It then continued to blow after about 10 seconds on each attempt. (Fortunately I stocked up on 30 amp fuses!)
I have NO idea what's going on here. Any suggestions are appreciated. I even put a coat of white lithium grease on the landing gear in case they were dragging.

Best wishes to all!
Ian

22 Replies

  • it is common for an AC motor to draw more amperage with low voltage - impossible for this to happen with a brush type DC motor UNLESS

    The non performance forces a person to lay on the switch and slowly but surely the motor heats up.

    usually a bad field coil will cause this but if the motor is permanent magnet a filthy commutator, grease and graphite can suck 30+ extra amperes.

    OR

    A mechanical failure in the slide or landing gear causes the motor to overwork. A hot battery allows the motor to pass through the bad spot.

    All of this is guesswork. The motor needs to be ampere checked free spin and the gear needs to be hand cranked to evaluate if it is binding.
  • Generally this is a dedicated circuit so I have to think it is a motor issue drawing too much power. Trace and inspect the wire after the switch for a short but I doubt that is the issue. Are you sure it is supposed to be a 30 amp fuse?

    It is common for a motor to draw more power with low voltage so possibly a bad connection or the OEM wire is marginal. I assume the motor seems to run normal and does not sound like it is straining.

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