blown fuse

[tjgord]

the TT has not been used for about 2 yrs and we got everything ready, hooked up and was on the road for 2 hrs. pulled in for gas and to fix lunch and noticed the lights would not turn on. the 30a fuse at the batt had blown. picked up a pack at auto store and blew 2 more. everything worked fine while we cleaned and loaded up. any ideas? thanks

[Quahog]

Welcome to the JOF, tigord. Sounds like something is shorted out. You might try flipping off the breakers and one by one flipping them back on to see if a particular load is the cause. I am sure others will jump in with suggestions.

[rwilley]

If none of the other fuses are blown which I'm guessing they are not cause they would have blown before the main one than the short is between the the main fuse at the battery and the fuse block. Sorry thats not much help but its hard to diagnose this far away.

[j4nash]

We have a similar problem everytime we unhook power to our trailer the fuse on the battery's blows

[tedshelleykacie]

I had the same problem on our last tent trailer. Found that it only occurred when connecting or disconnecting 7 way to the vehicle with it running. Once I turned the engine off I stopped blowing the 30A at the battery but I still continued to carry extras with me. I also verified that the ground to the chassis had a good tight connection. Hope that helps a llittle.
Ted

[Terry]

If it had not been used in a while it could have been caused by the battery going dead. I think I remember the old P=IV formula.... (Power in watts = current * voltage).....so as your voltage decreases, the current demand goes up.

[tjgord]

thanks for all the responses, the tt is about 6 hrs away and we are leaving this weekend to camp for spring break. the batt is about 5-6 yrs old so it would be time to replace. that would be an easy fix to my problem. thanks again!

[Murphie]

Where is David when you need him? Good call Terry, I don't think I would have thought of that. I have trouble trying to remember Ohm's law.

[tjgord]

Well folks, the new battery did not fix the problem. I also disconnected from shore power, was not plugged into the tow vehicle and all the breakers were off inside and still blowing the 30A fuse at the battery.

[David472]

Originally Posted by Murphie

Where is David when you need him? Good call Terry, I don't think I would have thought of that. I have trouble trying to remember Ohm's law.

Snoozing!

[drfife]

Originally Posted by tjgord

Well folks, the new battery did not fix the problem. I also disconnected from shore power, was not plugged into the tow vehicle and all the breakers were off inside and still blowing the 30A fuse at the battery.

Start tracing the wires, you have a short somewhere.

Possibly a rat or squirrel chewed though the insulation on the positive side and it's contacting metal somewhere. Just a guess......

[David472]

Originally Posted by tjgord

Well folks, the new battery did not fix the problem. I also disconnected from shore power, was not plugged into the tow vehicle and all the breakers were off inside and still blowing the 30A fuse at the battery.

The next suggestion would be to check the 12v wire where it goes from the fuse to the rest of the TT. Could be the insulation has worn through from rubbing against the frame. Could even have been chewed by some critter. Either way could result in a short, as Quahog suggested earlier.

[Terry]

Originally Posted by tjgord

Well folks, the new battery did not fix the problem. I also disconnected from shore power, was not plugged into the tow vehicle and all the breakers were off inside and still blowing the 30A fuse at the battery.

A couple of questions -

- You said breakers were off, those are for the 120 volt system. Are all of your fuses in the load center ok?
- Do the 12 volt systems works ok when plugged into shore power?
- There should be two 30 amp fuses in the load center, are those ok?

If there is a short in the wire going back to the battery, I would think it would also blow the fuse in the load center as it overloads the charge circuit.

[exjay1]

Originally Posted by David472

The next suggestion would be to check the 12v wire where it goes from the fuse to the rest of the TT. Could be the insulation has worn through from rubbing against the frame. Could even have been chewed by some critter. Either way could result in a short, as Quahog suggested earlier.

X2. Sounds like you isolated it from the fuse panel to the battery. inspect your wires going from the battery back to the fuse/inverter location. likely you may find a short along the frame rail etc like david said. keep us posted..

[hausknwa]

We had a similar problem on our 322FKS. Turned out to be a bad (poor) connection inside the fuse holder. We could feel the holder getting hot while drawing power. Installed a new fuse holder and never had a problem after that.

[RedHorse1]

All breakers off and still blows the 30A fuse. Something 86 in the converter? I'm no expert but that seems like that's the only thing still getting power.
Maybe crawl around the wires from the batt to the converter/fuse panel and look for rodent damage.
Fer sure a short, but where?
Keep posting your efforts (successes)!

Doh! didn't take time to read the 2nd page of postings. I see my stuff has been covered.

[RoyBraddy]

Everytime i see someone mention the battery just installed I always bring up how easy it is to get the battery installed backwards.

The thing to always do when installing a battery is always notice the battery case stamped "NEG" or "-" terminal and make sure this is the BATTERY CABLE that goes to the trailer frame ground connection which is near the battery location.

If you install the battery cable in REVERSE than you most often blow three fuses. Two will be in the Power Distribution Center and are usually off to themself and marked "REV POLARITY" or somethng like that. The other fuse will be an "IN-LINE" very close to the battery location sometimes under the trailer frame.

No HARM done except some blown fuses between the Battery connection and the Power Distribution Center connection.

It is very easy to reverse the battery connections so always keep this planted in the back of your mind everytime you touch the battery cables.

The same thing will also happen if you spark the battery cables when being installed touching the wrong terminals.

Alot of folks will use one of those cable markers you find at the autoparts stores and identify POSITIVE and NEGATIVE on the battery cable ends as another reminder which battery terminal they go to.

I have a BATTERY DISCONNECT SWITCH installed in my installation and never remove the batteries. If I need to isolate the battery for some reason when parked I Just switch the battery out of the circuit.

Dont know if this is causing your problem or not but definately needs to be looked at as possible cause.

Having a digital multimeter on hand when working around batteries is a "MUST HAVE" item for the RV Toolbox. They are very inexpensive ($7-$20) from Lowes-Walmart-AMAZON-any number of autoparts stores)

Similar to this:


My Digital Multimeter is a high dollar FLUKE model from my Systems Engineering working days but the inexpensive models from the local stores work just the same. Pick one up... Then you dont have to guess anymore why something isnt working DC Voltage wise. "Hmmm lets see" you are thinking... "yep I am reading 12.6VDC on the battery terminals with the Shore Power cable removed." Then measure the "BATTERY CABLES" connections at the Power Distribution Center terminals. You say "Hmmmm nothing here." Then you say to yourself "I must have a blown fuse somewhere or a bad battery terminal connection or my battery disconnect switch is open"... Now you can go look somewhere instead of just guessing what is wrong.

I wouldnt be too concerned about talking out loud unless the trailer starts answering your comments...

[202Acadia]

Originally Posted by RoyBraddy

Everytime i see someone mention the battery just installed I always bring up how easy it is to get the battery installed backwards.

The thing to always do when installing a battery is always notice the battery case stamped "NEG" or "-" terminal and make sure this is the BATTERY CABLE that goes to the trailer frame ground connection which is near the battery location.

If you install the battery cable in REVERSE than you most often blow three fuses. Two will be in the Power Distribution Center and are usually off to themself and marked "REV POLARITY" or somethng like that. The other fuse will be an "IN-LINE" very close to the battery location sometimes under the trailer frame.

No HARM done except some blown fuses between the Battery connection and the Power Distribution Center connection.

It is very easy to reverse the battery connections so always keep this planted in the back of your mind everytime you touch the battery cables.

The same thing will also happen if you spark the battery cables when being installed touching the wrong terminals.

Alot of folks will use one of those cable markers you find at the autoparts stores and identify POSITIVE and NEGATIVE on the battery cable ends as another reminder which battery terminal they go to.

I have a BATTERY DISCONNECT SWITCH installed in my installation and never remove the batteries. If I need to isolate the battery for some reason when parked I Just switch the battery out of the circuit.

Dont know if this is causing your problem or not but definately needs to be looked at as possible cause.

Having a digital multimeter on hand when working around batteries is a "MUST HAVE" item for the RV Toolbox. They are very inexpensive ($7-$20) from Lowes-Walmart-AMAZON-any number of autoparts stores)

Similar to this:


My Digital Multimeter is a high dollar FLUKE model from my Systems Engineering working days but the inexpensive models from the local stores work just the same. Pick one up... Then you dont have to guess anymore why something isnt working DC Voltage wise. "Hmmm lets see" you are thinking... "yep I am reading 12.6VDC on the battery terminals with the Shore Power cable removed." Then measure the "BATTERY CABLES" connections at the Power Distribution Center terminals. You say "Hmmmm nothing here." Then you say to yourself "I must have a blown fuse somewhere or a bad battery terminal connection or my battery disconnect switch is open"... Now you can go look somewhere instead of just guessing what is wrong.

I wouldnt be too concerned about talking out loud unless the trailer starts answering your comments...

Unfortunately I have hooked up batteries backwards and am ashamed to say more than once. Blew the REV POLARITY fuse at the converter, but also resulted in having to replace a weakened circuit breaker in the + cable from the battery.

[Edcamp]

You need to find wiring diagrams for your TT you must find out what all is on that circuit then physically look at what wiring you can see for obvious frayed wires, melted sockets etc. You must isolate the circuit to find the problem. Was an electrical wizz in my auto repair shop of 35 years. Electrical was my strong suit. Hope that helps?