12 volt junction block

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z10kl

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Joined
May 8, 2007
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18
On my 2004 Cedar Creek fifth wheel sometimes I have no 12 volt power except to the slide outs. I started checking and at the junction behind the battery there was no power on the bottom left stud. There was on the others. If i wiggle the stud the power returnes. Is there a reason this stud appears isolated from the others? It is not connected by a copper bar. Does this block have any other purpose other than connecting the leads? Does it sound like it is broken and losing contact? Shoul I replace it or just add a jumper to give it power from another stud?
SAM_0526.jpg

 
Here's the pic.
Edit: Removed duplicate attachment.
 

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No, it's the same. It posted twice. The botom left looses power for some reason.
 
z10kl said:
If i wiggle the stud the power returnes. Is there a reason this stud appears isolated from the others?
Click to expand...

I would remove the terminals and very thoroughly clean each, as well as the stud, reassemble and tighten the nut. If that doesn't help, the problem is most likely the connection to the strip, although the picture seems to indicate that this is just a common connection point. If so, perhaps the terminals on the wires are corroded inside the terminals. Does it make any difference whether you wiggle the wire terminals or the wires?

Richard
 
It's in the block. If I move the stud It connects. It will be fine for a while then looses connection.  I'm sure if I put a jumper across the studs it would stay on but I wonder if there is a reason why they are separated.
 
The lower terminal is actually connected to the upper terminal through an internal circuit breaker. (That little black dot at the top is a reset button).  Here is what that terminal arrangement really is. 

The same can be said for the upper and lower BUS bars, they are connected through a circuit breaker on the right side of the photo.

The breaker is probably defective internally at one of the terminals.
 
That looks like the breaker for Power tops and windows on some of my classic cars. That makes since. Maybe I should just change it to see if it helps. I will look closer to see how many amps it is.
 
The heavy Red Wire at the top is probably coming from your Battery.  The devices to which it is connecting are some kind of fuse/ckt breaker (could be self-resetting).  The copper strip across the top is supplying power to the three 'fuses'.  The two Fuses on the right are connected in parallel (the short copper strip on the bottom right) and the output of those two fuses is probably going to your slideouts (paralleling the fuses increases the current carry in capability).

The fuse on the left is a single fuse and is probably supplying your DC Fuse Panel.

If it isn't corroded or loose connections (which doesn't seem to likely from the pictures you posted) I would suspect the fuse and replace it.  You should be able to get one at NAPA.  I am curious, do you have power for some period of time after you wiggle the stud??  If it is a self-resetting fuse it may not be making contact when it resets or a vibration is causing the internal contacts to quit making contact.
 
Yes the power stays on for some time. I am useing a generator in some of the time. I know when I left the camper last Sunday the 12 volt was on and when I got there Friday it was off. Everything was off while I was gone.
 
aka Porky said:
The lower terminal is actually connected to the upper terminal through an internal circuit breaker. (That little black dot at the top is a reset button).  Here is what that terminal arrangement really is. 

The same can be said for the upper and lower BUS bars, they are connected through a circuit breaker on the right side of the photo.

The breaker is probably defective internally at one of the terminals.
Click to expand...
Ahh, thanks for the explanation.  I'dve been tempted to just put a jumper between the two posts and be done with it.  This 12 VDC stuff sure isn't obvious like the breaker panel on 120 VAC stuff.
 
Don,t put a Jumper on it other than for a momentary test.  The Fusing device is there to protect you, the battery and wiring, you stand a good chance of fire if you Jumper it.

Replace the fuse.
 
Well, that is not a junction block, it's 3 circuit breakers with one terminal common to all 3.

Take a look at this URL 12 volt circuit breaker

Notice how there appear to be 3 devices much like this behind that top bus bar.

You have a single breaker on the left, and two more which are paired to increase current capacity on the right.. yes, they are metal cased where the one I point you to is plastic, but the save for the case the shape is about the same.

You need to replace that left hand breaker.  Remove it, the case should have the capacity either printed on or stamped in, go to any auto parts or RV store and they will have a new one, BE SURE TO LABEL ALL WIRES BEFORE DISCONNECTING.

I would recommend a pair of zip ties,  First remove the bottom wires, slip the lugs over the zip tie and a add a key tag that reads "Bottom" and zip it locked, then do the same with the upper lug but label it "TOP" that way you won't play "Which wire" when you hook it back up.

DISCONNECT both batteries and 120 volt power before doing this.
Edit: Fixed link.
 
Those are definitely thermal circuit breakers.  The little black button on top will reset them when pushed.  If it is the right hand side giving you the problems make sure both are reset or you are trying to pass all the current thru one.  If they are located in a hot area they will trip at a lower amperage than rated.  Especially if they are in an engine or generator compartment.
 
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