What is This Wire With a Box on My RV's Battery?
Strange Wire on RV Battery Explained
What is the somewhat flat plastic box (Pictured Above) on a 2014 Catalina Travel Trailer which connects to the battery positive post?
It branches off into two lighter wires. This TT has an electric tongue jack. I disconnected both the positive and negative cables last fall at the campground and this piece has gone missing. I do not know where it went or what it is for. The only reason I know it had this apparatus is because I took a photo with my camera before I disconnected the cables. The only thing I could find to connect is the red positive and white negative cables.
I am also wondering if it is harmful to connect the battery and shore power without this box?
ANSWER: The wire on your your travel trailer's battery is an In-Line Fuse Holder and yes you need to have it connected to your battery to prevent possible wiring, battery or fire damage to your Travel Trailer.
The little box on the wire (circled in the picture at the top of this page) contains a Blade Fuse
. If too much current goes through the in-line fuse, the Blade fuse (like the ones pictured above) will blow preventing the current from flowing to the battery. If the wire leading to your trailer's battery grounds out or receives a high voltage spike it can start to damage your RV's battery and start melting the wiring immediately. This can also start a fire from melting wiring and insulation. In real extreme cases the battery itself could explode. The in-line fuse prevents all of this from happening by blowing before all of the above damage can occur.
Battery Disconnect Switch
You mentioned that you lost the in-line fuse when you were disconnecting your RV's battery for the season. To prevent this from happening again, I would suggest that you install a Battery Disconnect Switch
(pictured above) on your travel trailers's battery. A battery disconnect switch allows you to shut off the connection directly at the battery without having to disconnect the actual cables.
I hope that this information has been helpful.
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