What is this gizmo on my battery? - Page 2 - Fiberglass RV

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Old 10-24-2010, 01:50 PM   #15
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Name: William
Trailer: 1999 17 ft Casita Spirit Deluxe ('Inn EggsIsle')
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Originally Posted by Lawrence W View Post
Thanks for identifying that item...could you be more specific about the incorrect installation? The connections are (positive): to battery positive, and from the circuit breaker to the trailer fuse (I also have power to the breakaway switch wired to this post); (negative) to frame ground and to trailer ground wire. I think Carol and you were right about the installer weren't aware of the trailer fuse.
this circuit breaker is an automatic setting breaker, about $4.00 bucks at any auto parts supplier. if it heats up it becomes disconnected and when it cools off it comes back to life. If they really take a surge they will completely blow and need to be replaced

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Old 10-24-2010, 02:37 PM   #16
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Trailer: 2005 13 ft Trillium Outback
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Ah, yes. The circuit breaker should only be connected in series on the positive line from the battery. No negative side connections. A series connection is when a single line is cut and one end of the cut wire is attached to each terminal. There should only be one connector on each terminal of the circuit breaker. This forces all current being drawn from the battery to go through the circuit breaker. When more amps than it's limit are reached it disconnects internally and stops current from flowing. When it cools, it resets.

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Old 10-24-2010, 04:27 PM   #17
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Trailer: 2005 19 ft Scamp 19 ft 5th Wheel
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Clarifying a bit, here are three line drawings that show how trailer 12v wiring and fuses/breakers should be wired. The first is a simplified version that shows how a trailer might be wired if it has no converter or charge lines coming from the tow vehicle. The second shows how the factory wiring for my Scamp (and who knows how many other trailers) was done, the third shows how my Scamp ought to have been wired, with the fuse on the tow vehicle wiring appearing on the wire branch that heads up to the tow vehicle, instead of placing a second breaker on the main charge line.

I do not like using thermal breakers like the one in your picture by the way. They are not a safe way to do things.

Main fuses are meant to protect your trailer from a short that could start a fire or cause some other dangerous mishap. (And, yes, there's plenty enough juice in a fully charged trailer battery to start a fire.) So, should your trailer develop a dangerous short, the line would short and spark, overheat the breaker so it breaks the circuit, then cools off, reconnects the circuit, allows it to short and spark again, overheat the breaker so it breaks the circuit again, cools off and reconnects . . . and so on until you either get a fire, or your battery goes dead. The only good solutions for a main fuse are a resettable breaker that you have to manually reset or a regular 25A or 30A fuse.

Simplified Concept:

Ground                            12v Distribution   Individual
Wires             Main                Panel          Line Fuses
───┐   Battery    Fuse                  ┌────────────────∩────── < Trailer
───┼─────╫╫╫────────∩───────────────────┼────────────────∩────── < Lights &
───┘    -   +   or Breaker              └────────────────∩────── < Appliances
How my Scamp is wired:

Ground                            12v Distribution   Individual
Wires                                 Panel          Line Fuses   Converter
───┐                                    ┌────────────────∩──────< Charge
   │                Main      Secondary │                         Line
   │    Battery     Fuse         Main   │
───┼─┬────╫╫╫────────∩────────┬───∩─────┼────────────────∩──────< Trailer
───┤ │   -   +   or Breaker   │  Fuse   ├────────────────∩──────< Lights &
───┘ │                        │         └────────────────∩──────< Appliances
     │-                      +│
 Tow Vehicle              Tow Vehicle
 Charge Line              Charge Line
How I wish my Scamp was wired:
Ground                             12v Distribution  Individual
Wires                                  Panel         Line Fuses   Converter
───┐                                    ┌────────────────∩──────< Charge
   │                Main                │                         Line
   │                Fuse                │
───┼─┬────╫╫╫────────∩────────┬─────────┼────────────────∩──────< Trailer
───┤ │   -   +   or Breaker   │         ├────────────────∩──────< Lights &
───┘ │                        │         └────────────────∩──────< Appliances
     │                        │  
     │                        « < Tow Vehicle Charge Line Fuse 
     │                        │
     │-                      +│
 Tow Vehicle              Tow Vehicle      
 Charge Line              Charge Line
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Old 10-25-2010, 03:57 PM   #18
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Name: Kevin
Trailer: 13' Scamp
Posts: 15
Here is another question for all of you. I have an older converter in my '92 13ft scamp that is labeled "not intended for charging the battery". So based on that I want to make sure it does not try to charge my battery since it probably will not be good for the battery in the long run. My question is, is there anything I can do short of unplugging the battery while using the converter that will protect me? Thanks for any help.
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Old 10-25-2010, 04:18 PM   #19
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Trailer: 2009 Trillium 1300 "Homelet"/2014 Subaru Outback "Rosie"
Posts: 2,181
Is there any brand information on your converter? If so, look it up and see if they reccommend a replacement that can charge the battery.
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Old 10-25-2010, 05:07 PM   #20
Name: buddy
Trailer: bigfoot b17/13 boler/15trillium
Posts: 48
gizzmo on your battery

Originally Posted by Lawrence W View Post
I'm preparing to completely rewire my '80 Scamp, install new marker and taillights. I'm making a diagram of the complete system (similiar to the Scamp diagram, except it includes battery, my particular appliances, breakaway switch, and the original Scamp color wiring.). The RV dealer in California, where I purchased the trailer, installed the battery and got the lights working so I could tow it back to Oregon. He installed a two-post device between the battery terminals that they are connected to. What is this device, and what is its purpose?
It is probably a type of fuse to protect the circuit in case of a short. you can leave it on or wire your fuse box normal some wires from the battery to the fuse box are a type of fuseable link but it looks like a normal wire. Hope it helps. Bud

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