Main fuse blowing - why?

03-22-2012, 10:17 PM

So last summer I took my trailmanor to Yosemite and the ground wire touched the positive wire and shorted both batteries. Kind of a bummer, but it was ok as I had a fuse to make sure I did not blow anything up as it could have been a fire or something else bad.

Here is my question:

1. How come when I use the trailer I cannot turn all the lights on without blowing the fuse up front with my new battery?

2. Is there a way to put water in the trail manor with it all closed up? Seems like a pain to have to undo it and put water in it when I get to the campground.

Let me know as I must get these issues resolved before my one month travel up and down the coast of Cali.

Thanks,

Brent

03-23-2012, 05:54 AM

1. How come when I use the trailer I cannot turn all the lights on without blowing the fuse up front with my new battery?
You don't say where the short occurred. What size fuse did you put in line. The std fuse is 30A. If you are blowing the 30A fuse with a few lights and nothing else on, you still have a short somewhere. Does the fuse blow immediately?

2. Is there a way to put water in the trail manor with it all closed up? Seems like a pain to have to undo it and put water in it when I get to the campground. There have been several discussions as to mods that can be done to fill the water tank with the TM closed. I suggest a search.

03-23-2012, 11:31 AM

The fuse I am using I believe is a 30A fuse and the lights work for like 5 minutes and then go off. We had the heater running when it happened so I don't know if that played into it or not.

I will search for water filling options as I would love to be able to do this without opening up the trailer.

Brent

**Bill** · 03-23-2012, 04:17 PM

Quote:

Originally Posted by hwork50

The fuse I am using I believe is a 30A fuse and the lights work for like 5 minutes and then go off. We had the heater running when it happened so I don't know if that played into it or not.

A 30-amp fuse located at the positive battery connection is correct.

When you say "heater", you mean the furnace, right, rather than an owner-supplied electric heater?

It sounds to me like you have a wire or a socket or a device that is very nearly shorted, but not quite. As the device heats up, something moves or expands, and the hot wire touches ground, creating the short.

The diagnosis is easy, though time-consuming. Turn off everything. Then turn on one light and leave it on for 10 minutes. If it pops the fuse, you have found your culprit. If it doesn't, turn it off and turn on another one for 10 minutes. Include the furnace in this lineup, as well as any other 12-volt devices that you were originally using. Eventually you will find the device that blows the fuse. (Of course, the techies among us would suggest using a binary search, to speed up the process. You get the idea.)

Quote:

I will search for water filling options as I would love to be able to do this without opening up the trailer.

Your free trial access expired some time ago, so you won't be able to find anything in the Plumbing or Tips-and-Tricks forums, where these posts most likely reside. To regain full access, go to the entry page of the forum at www.trailmanorowners.com, and click the link for Sponsorship.

Welcome back!

Bill

**Bill** · 03-24-2012, 08:38 AM

The more I think about this, the more I don't understand why the main fuse blows, rather than one of the smaller branch fuses.

Have you replaced the fuse holder, or do you still have the white nylon (plastic) tubular fuse holder?

Bill

03-24-2012, 03:31 PM

So I looked at the fuses and it seems as though we had a 3 AG amp fuse in the line between the battery and the TM. We upped the fuse to an 8 amp, we think as it said 8 on the box and it practically started a fire in my buddies garage. We share the TM and he owns half and I own half.

The little in line fuse problem just got a little bigger.

Let me know your thoughts Bill or Bob on this.

Thanks,

Brent

03-24-2012, 03:34 PM

We have 2 batteries up front hooked up in sequence and the fuse is spliced off of the positive post.

Keith Wire · 03-24-2012, 04:00 PM

How comfortable are you or your "buddy" with electricity?

You say you have two batteries up front do you know if they are connected in series or parallel? If they are 6Volt batteries they should be connected in series. If they are 12 volt they should be connected in parallel. If you or your buddy are not sure you should get someone else to make sure things are connected correctly.

The fuse between the batteries and the TM should a 30 AMP fuse. Most of us have replaced the round glass type fuse and holder with either a 30 AMP circuit breaker, or a 30 AMP blade fuse.

Check it out and let us know how the batteries are wired, and exactly what type/size fuse/fuse holder you have between the batteries and the TM.

Keith

03-24-2012, 04:08 PM

We have 2 6 volt batteries in there and we have the plastic holder for the fuse. I will have to get an electrician friend to look at it as I want this thing to work right and not have any probs as the TM will be in use all summer.

Bummer!

Brent

**Bill** · 03-24-2012, 04:46 PM

Now you have me really confused. Are you saying that you had a 3-amp fuse in the main fuse holder in the battery line? Or an 8-amp fuse? What led you to do that? If you turn on a bunch of lights, I would expect either to pop. Each dual light fixture takes more than 2 amps, so if you turn on 2 or 3 of them, you are done if you install an undersized fuse.

I have no idea what "started a fire in my buddies garage" means. What actually happened?

Way back in your original post, you said that you experienced a short that blew the main fuse, which was presumably a 30-amp fuse at that time. I am now thinking that the short not only blew the fuse, but also overheated the fuseholder. I don't have many pet peeves with TM, but that fuseholder is one of them. It is quite intolerant of even normal loads, and it is common for it to overheat (often indicated by one or both ends turning brown). At that point it loses good contact with the body of the fuse, which causes more heating, and the fuse can pop not from an overload, but just from the heat. As Keith mentioned, many of us have replaced that fuseholder with a flat automotive blade-type fuse and holder.

Finally, a "3AG fuse" is not necessarily a 3-amp fuse. The designation "3AG" refers to the body size and style. But 3AG fuses come in a wide variety of current ratings. A quick hit on Google might make this more clear.

To reiterate, you should have a 30-amp fuse in the main fuseholder at the battery - no bigger, no smaller. And I think you would be wise to install a new fuseholder with a blade-type fuse. If it's not clear what I am referring to, see a picture in this thread.

http://www.trailmanorowners.com/foru...ead.php?t=7760

Bill