Mini Fuse Blows at Altitude

[CamperGeoff]

HI Folks:

I have a 2008 Montana 3075RL. I have discovered on a few trips to the Sierras that at altitude, when I Retract my landing gear to lower my unit onto my truck, the mini-fuse blows out. I have to equipment myself with about a dozen 30 amp minibuses, or manually crank the gear down.

This happens only at altitude (not a sea-level where I live). Does not matter if I am on power or batteries.

does anyone experience this? If so, is there a solution?

Regards,

CamperGeoff

[hankpage]

Wow! I have never heard of this .... usually the fuse blows when raising the trailer. I live close to sea level (and getting closer every year) and camp near the ocean or gulf also. Just to play it safe I may have to increase my stock of fuses if I plan a trip West. If it is only tripping when lowering I would suspect something is binding causing the overload. (but I still can't see why altitude would affect it) Hope someone else can offer you some help, Hank

[CamperGeoff]

HI Hank:

Thanks, yes it is very interesting. Intuitively you would think that raising would put increased pressure on the motor, but it seems to only happen when lowering, and only when I am in the mountains (7000+ feet).

Make the trip out West. I started taking my family to all the National Parks from the Grand Canyon, Yosemite, Zion & Bryce, along with the California parks, including Mammoth Mountain (eastern Sierras). Each is spectacular and well worth the trips.

Regards,

~geoff

[JRTJH]

You're so right, the national parks in the west are so awesome......

Now, as for your fuse issue. It seems to me that a few years ago, Keystone had an issue similar to yours. They installed two auto reset circuit breakers in parallel to resolve the issue. There's a thread on here somewhere that's a couple years old. Do a search and see if maybe it might address your issue. And, even if you can't find it, installing a circuit breaker in the fuse holder (NAPA has them) you will save the cost of the CB just in fuse savings :)

[PND]

What usually blows fuses is excess current. This could be a hard one to track down, but I would look for any losse conections, battery condition, AC voltage value where you are having this issue. Current value is based on voltage and impedance (resitance in a DC circuit). If you could put an ammeter in your motor circuit (must be in series) and track what it is as you run our motor in different areas. If you haven't done so yet, make sure your battery terminals are clean. If there is dampness in the air (coast) and dryness (mountains) there could be a differance in impedance at any corroded or slightly loose connections. This may help or not. Keep us informed as to what you find.

PND
2013 358RLT Mountaineer
2012 2500 Silverado

[PND]

John said "It seems to me that a few years ago, Keystone had an issue similar to yours. They installed two auto reset circuit breakers in parallel to resolve the issue." I for one, like to find the root cause rather than mask it. Paralleling two fuses or circuit breakers splits to current across them. Almost indicates bad connection at the fuse terminals. One other thing that I have had in the past is wire too small (wrong gauge) which again increases current in the circuit. Good luck!

PND

[raytronx]

Used to blow fuses in my Cougars landing jack cct. Installed the auto res-settable type and problem went away, maybe it has a little longer delay time than the standard fuses.

[PND]

Circuit breakers operate thermally, so yes, there is a slight time delay and most auto type fuses are quick acting. If I start having this issue with my new trailer, I will be connecting an ammeter to see just what the draw is. If I do, I will post the readings for all.

PND

[CamperGeoff]

I want to thank all of you for your help. I will check out each solution and let you know what works.

[CamperGeoff]

Ok, what a crazy weekend. Friday I blew 10 30A mini's trying to raise and lower my 2008 Montana 3075 RL. Painful hand cranking to get it done.

On Sunday at check out, no problem. Batts are fine, circuits test fine, motor hits a jam and blows fuse. Can seem to clear the jam (maybe bad gear teeth)?

Anyway, resettable fuse may be ok, but to cure the problem instead of managing the symptom, I am considering replacing the motor (did this before on my old Sprinter slide out motor) and it went away.

Anyone have a similar experience?

~g