Yet Another 30 Amp Fuse Question

[FIREBUGMAN]

The other night I just happened to come across one of the many threads regarding the 30A fuse at (or near) the battery. Today, before I started on my LED step light project, I decided to look for ours. On our 16XRB, it is not located near the battery or underneath - it is located inside the trailer at the front where the "bird's nest" of wires comes thru the floor and behind an access panel underneath the front dinette bench. Not a very user-friendly spot for such an important fuse.

Our trailer has only been out of storage for a couple of weeks and has been plugged in to shore power since we brought it home. So, just for kicks, I decided to test our 12v system. Sure enough, I unplugged and there was no 12v power. Battery was fully charged. I went back inside and checked the fuse. Sure enough, it was blown. Replaced it with a new one and all was well again.

My question is: we do not have a power jack and I did not hook up the battery incorrectly (I labeled the cables). What else could have caused the fuse to blow? Except for de-winterizing and sanitizing, we haven't really been in the trailer since it's been home.

If it matters;
--In the Fall, I may have disconnected the battery while the trailer was plugged in to shore power.
--It was towed to our storage place (and back) with no battery and it's possible that the cable ends could have come into contact with each other during the trip either to storage or back home while hooked up to the TV.
--I probably hooked the battery back up while it was plugged in to shore power.

Thoughts or ideas?

Thanks in advance!!!

[RoyBraddy]

I would want something close to the battery terminals to trip OFF in case of dead short to frame ground between the 12VDC Power Distribution Panel and the Battery terminals...

This is a 30AMP IN-LINE fuse in the older trailers installed right at the battery terminals... If a short down stream from the battery is present then the battery being able to produce a very very high DC CURRENT will smoke the battery cables and may result in a fire. This may also result in the battery exploding... The main purpose here is to protect the Battery and the wiring from a direct external short circuit to frame ground....

The newer trailers may have an MANUAL RESET CIRCUIT BREAKER in this location in place the large value fuse...

Might want to check for that in your installation... I would think the best safety code would have something that would trip OFF right at the battery terminals to prevent a fire from overloaded cables or exploding battery case.

My battery bank in addition the main trailer 12V FEED also has my ROOF RAISE motor circuit, Truck charge line, and Break-Away Switch 12VDC source direct connected to the battery terminals. The ROOF-RAISE circuit is a large Value manual reset Circuit Breaker setup... The Trailer SLIDE OUT units will also be direct connected to the battery terminals using some sort of MANUAL or AUTO Circuit breaker function.

If this is a pre-used trailer setup who knows what may have been added by previous owner... There are also usually a couple of large value fuses near the 12VDC power Distribution Center that are called REVERSE POLARITY fuses... These are suppose to blow when you accidentally connect up your battery terminals in REVERSE ORDER. Mine are mounted on the ATC Fuse panel strip itself in the 12VDC Power Distribution Panel...

Also be mindful your installed and working battery on the trailer also provides 12V power for your DOT REQUIRED BREAK-AWAY switch functions and I always check my 12V connections for this when I tow my trailer. This provides emergency brake actions for stopping your run-away trailer if it becomes disconnected from the truck while being towed over public roadways.

Roy Ken

[FIREBUGMAN]

Hey Roy,

Our trailer is a 2016 and that is where Jayco installed the fuse. And you are correct, the Reverse Polarity fuse is in the "breaker/converter" box. My reverse polarity fuse did not blow, probably because I hooked up the battery correctly.

And I agree about the Break-Away switch but I admit that I kind of forgot about that and our storage place is not too far from home. In the future I will remove the battery after we park it for the winter.

My question was - could one of the other things that I listed have blown the fuse?

I have a supply of the 30A fuses now, but I'm thinking that the auto-reset breaker idea might be an option instead.