Small (but very scary) electrical fire

[JT4SC]

I'm beginning to think I shouldn't be taking the Moose this weekend...  I believe I got the power steering issue resolved, so I started her up to get some diesel when I saw smoke coming from the battery compartment.  I opened the door and saw a small fire at a solenoid (pictured) above the lever that turns the bus power on and off.  A seperate black wire from the solenoid runs into a devise that deals with the main bus batteries (black box pictured) and the red wire that was frying runs back to a junction at the house batteries (red dial pictured).

Did the house batteries (which are old and need replacing) or that black box short out the solenoid?   And what the heck does that solenoid do?  Is this something that shouldn't affect much and I can work on fixing it when we get back, or should I make alternate travel plans?

Thanks in advance!!  Heart is now slowing down a bit, that was scary!!

[azdieselman]

Not to be picky, But that's a relay.

It looks like it melted just below the eyelet. Did it come in contact with the wall the relay is mounted to, and short to ground?

[JT4SC]

Not to be picky, But that's a relay.

It looks like it melted just below the eyelet. Did it come in contact with the wall the relay is mounted to, and short to ground?

Good to know the correct term, thanks AZdieselman!  I can't tell now if it came in contact with the wall since its been fried off, but I can say it's been installed like this for the last 7 years since I've owned it with no issues.  What does this relay do?   The bus ran just fine while the wire was frying.

[buswarrior]

I would consider the entire length of that red wire as now damaged, unless it can be proven otherwise, that a great current may have flowed through it.

The crimp may have simply given up due to corrosion, small contact area, poor workmanship in assembly... yes, the difference between good and bad can show years later.

The direction the connection appears to be pointing, could the wire have been. Touching the wall? Vibration introduced inside a crimp such as this isn't good.

You need to make yourself some schematics of where the wires all go, it is hard to trouble shoot someone else's "custom" install.

Happy coaching!
buswarrior

[JT4SC]

Here is another picture of the back of wire if that helps.   Can anyone tell from the different pics what this relay does?  

[eagle19952]

the way it is mounted is scary...
the wires are kinda small for the capability of the solenoid contactor ... imo.

was the burnt wire output or input ?

[Iceni John]

Is there a suitably-sized Class-T catastrophe fuse (Sean W recommends them on the Negative lead from the batteries), or individual load fuses on the Positive cables?   That setup looks scary to me.   Why is the Blue Sea 9001 switch mounted that way?

I think it's time for a complete reevaluation of the circuits there, including replacing any and all suspect cables and equipment.   I'm also wondering if the cables are undersized  -  I would suggest going one size larger than their theoretical ampacity ratings, plus also increasing size if they're in a hot area.   Lugs should be crimped "gastight", and if that's not possible they should be filled with solder AFTER they've been well crimped, provided the cables won't need to move at all.   If they need to move, don't solder them!

Once everything's been redone and is up and running, check the lugs' and cables' temperatures with an IR thermometer  -  that will tell you if you have a bad connection under full load.

John

[John316]

Here is another picture of the back of wire if that helps.   Can anyone tell from the different pics what this relay does?  

Here's my wild guess. Could that be a switch for charging the batteries either from the genset or the bus alternator?

[eagle19952]

if the relay/contactor was turned 90 degrees you would eliminate a LOT of stress on the wire lugs.... too many right angles.

The screw is not holding...the washer is.

It all matters.

When you see these things it leads to other "unseen" concerns ... at least to me.

[luvrbus]

It's to jump or charge the starting batteries from the house batteries or charge the house batteries from the starting batteries depend on how they set it up would be my guess typical RV setup on the S&S  

[digesterman]

Azdieselman,
I have always called those solenoids;

http://www.delcity.net/store/Solenoid-Switches/p_741262.r_IS3011?mkwid=6pWurPvG&crid=3892708426&mp_kw=12v%20solenoid&mp_mt=b

http://www.delcity.net/store/Relays-&-Power-Distribution/

what exactly makes this one a solenoid? Just curious

[JT4SC]

Thanks for all the replies guys.  I have attached a wider view picture of the battery compartment, with the relay in question near the top.

I believe this set up does have to do with charging the starter batteries, I remember when I bought the bus Mike K told me he was going to run a new wire so the batteries would get charged while we were running the bus (I assumed like an alternator).  He hooked up the wire from the electrical board outside/below the drivers side window to the battery compartment.  From there I didn't see what he did.  Just now I opened up the electrical compartment, found the wire he hooked up, and saw its the same type of wire that connects to the very right-hand side of the relay.  In the picture you can see the wire Mike installed going out from the right side of the relay into a hole in the batt compartment.  That wire looks fine.  The middle wire runs to the black box, and the left red wire is what fried, and it runs back to the house batteries.  

Does seeing the whole battery compartment and all the wires still look poorly done or does it appear now to be a little more normal?  

[luvrbus]

I never saw that small gauge of wire used in that application before even on a S&S RV

[JT4SC]

I never saw that small gauge of wire used in that application before even on a S&S RV

What does and S&S RV mean?

[eagle19952]

What does and S&S RV mean?

Sticks and Staples.... any RV that is not a converted coach...