REALLY blown 30 amp fuse?

Ok, so this morning, while we were hooked up to shore power, DH and I both heard this strange "rat-a-tatting" noise just outside the sleeping quarters. We didn't really get what it was. We tore down and got on the road.
When we reached our destination this evening, we plugged in to power ( or thought so) I didn't hear the "converter noise?" near the bathroom. I checked the battery test button and it was red. ( we are still hooked up to the truck)
DH checked the battery in the back, and the fuse was blown and melted both sides of the plastic. Any ideas as to what this is and why this happened? This is a new battery. We disconnected the battery from the system.
Any insight would be appreciated
Thanks, Liz K

[Keith Wire]

Hi Liz,

Most of us have had a similar experience with the original fuse holder. Mine lasted about 6 outtings before burning up.

I replaced mine with a blade fuse holder instead of the 1-1/4" round fuse holder that was installed. Others have installed an automatically resetting breaker, but I couldn't find one when mine burned out...

So just replace it and "keep on camping".

HTH,

Keith

[cochise]

Somehow there is/was a load in excess of 30A applied to the supply line. Most likely it is a wire that have had its insulation damaged so the BARE wire is exposed and rubbing against ground (the frame of the trailer). TraiManor, and probably others too, are not known to sufficiently protect the wiring harness of their product. Look under the trailer at the wiring from the brakes, and you should get the idea. My furnace was placed loosely, not secured to the floor, on top of a total of 10 12V wires. It is now going back to the shop to have this problem corrected, and while the furnace is out the two bunches of wires will be properly sheated in flexible conduit, as will the brake wiring. They will also remove the non-code wirenuts and replace those with crimped connections. Electricity no matter what voltage is no toy. Respect it! A shorted 12V circuit can be as dangerous as a 120V circuit, albeit in a different way. Car fires are usually started by the 12V circuits or if a large truck or bus the 24V.

Check your wiring for a short between the battery and the converter.

[Keith Wire]

Cochise,

Certainly a short somewhere in the TM would cause the fuse to blow and it could cause the fuse holder to melt, but it is NOT necessarily true that there must be a short in the wiring.

In my experience with these 1-1/4" glass fuse holders it is just a matter of time before they go bad. The plastic and the spring melt together and they start generating heat and burn out the fuse. Im my case it was obvious that it had arced before it blew, which is the noise Liz probably heard when theirs burned out.

I have replaced them in mowers for 30 years and when I saw the one in the TM I knew it was just a matter of time before I had to change it there as well.

Keith

If you had a dead short ( bare wire to frame) the fuse should blow quickly and not melt the holder. More than likely, the contacts on the holder got corroded and during storage the TM battery was a little low. When you plugged in at home the converter started charging the battery at a fairly high current level. That current going through the corroded contacts ( high resistance) melted the holder. I replaced the glass fuse holder with a large blade fuse holder and used a 30A breaker with blades. This is the best of both worlds as if the breaker finally dies, I can replace it with a standard 30A blade fuse.

My original fuse holder charred and melted the first time I ran the TM refrigerator on 12 volts while traveling. It more or less tuned itself into a resistor. Lucky that it did not burn more. Swapped out with the blade type fuse and have had no problems since with 30 amp fuses or holder.

I have no fuse on my battery in my old '89. Where should it be placed, on the positive wire right at the battery terminal? I'll go get a 30 amp. blade fuse holder and some spare 30 amp. blades.

I replaced the fuse with a self resetting 30A breaker. This has worked for two years. Any problem with continuing use of a breaker?

[Wavery]

The fuse/breaker should be as close to the positive battery terminal as possible. Inside the actual battery box is best.......Any length of wire between the battery and the fuse is unprotected.....