Battery Wiring

[Don N]

I have installed a junction block inside the trailer for all of my TV wiring as well as the battery, which is mounted on the tongue. The TV has the hot 12 V wire hooked up so I can top up my battery as I am driving. I have wired the TV plug into the junction block and then am going to run a positive and negative wire from the battery back to the corresponding leads on the junction block. Intending to use 12 GA wire from the battery to the junction block. Do you think this will be heavy enough or should I use 10 GA ?
Should the hot 12V wire from the TV be hooked to the battery instead of the junction block? I have hooked all my inside 12V feeds to this lead on the junction block. I realize that if I leave my trailer hooked up to the TV it will run that battery down but I always unhook the vehicle from the trailer. Just want to make sure there is no problem wiring it up this way.
Once again, thanks for the help...

[Laura & Rick]

Use 10 gauge muti-strand wire for both positive and negative. Doesn't matter if you connect to the battery or the junction block, suggest you use the battery. But DO put in a 30 amp auto-reset circuit breaker in the postivie wire close to the source of 12 volts.

[Pete Dumbleton]

I use even heavier gauge wiring throughout because I want as little voltage drop as possible in the system.

I also prefer the auto-reset circuit breakers to fuses because the way you are going to discover a blown fuse is to have a dead battery that couldn't be recharged...

[Don N]

Thanks Pete. I was considering an inline fuse but wasn't sure of the amperage. I will get a circuit breaker to put in the positive line between the battery and the junction block.

[Pete Dumbleton]

When you are thinking about trailer wiring (internal, not the running lights), remember that the source of the power can be a number of things -- Coming from converter when plugged in to shore power, coming from tow vehicle charge system when connected and running, coming from TV battery when connected and not running and coming from the Egg battery.

[Don N]

Well, something is wrong in my wiring. Hopefully I can explain this properly. I have the 7 pin cable from the TV hooked up to this junction block which has 7 studs. Now, all of the 12V feed lines for my camper lights are hooked to the black 12V stud. All of the grounds for the 12Vcamper lights as well as the grounds for the running lights are hooked to the white ground stud. The brown for my RT turn and the red for my LT turn, green to the running lights and blue to the electric brake. The yellow Aux stud is bare. I have run a 10GA wire from the black stud back to a 30A circuit breaker and from the other side of the breaker over to the + battery. From the white stud, another 10 GA wire to a ground stud outside the box and then back to the - battery. Also installed a 10GA wire from the - battery post to the frame of the trailer.

1. Camper NOT plugged in. Black stud in junction box and the circuit breaker has 12.3V. The yellow aux stud is 0.0

2. Camper plugged into truck but truck NOT running. Both the black stud in the box and the breaker have 9.3V. The yellow aux has .25V BUT the running lights are on the camper and the truck running lights are on very dim.

3. Camper plugged into truck with truck running. The black stud in box and breaker are at 13.9V while the yellow is showing -.30V

Only thing I can figure is that I might have to run the black wire from the TV plug direct to the battery and then make up another wire to go back and feed the circuit breaker. The TV wiring works OK with my car trailer hooked up so it has to be something I have done in wiring up the camper. Also, when I was going to take the trailer out for its first run, the trailer brakes were on when the vehicle was moving without using the brake pedal. Must be a back feed somewhere. I have wired my 300W inverter up to the circuit breaker and outside ground stud but without camper plugged in, not enough voltage to even run my small portable TV/DVD player.
Can anybody shed any light on this? Want to head to Fla on Friday so will be correcting the situation tonight.
Thanks...

[Dan Meyer]

I'll make an educated guess or two:

For condition 2 - I'd guess that the camper battery is being discharged into the tow vehicle. If you disconnected wire at the positive battery terminal, what would the voltage be at the black stud in the junction box?

For condition 3 - I like seeing over 13 volts with the tow vehicle running - The battery is charging! I suspect the -0.30 volts at the yellow stud is simply noise.

Are all of the tail, running, stop and turn lights working properly?

Finally, the fact that your inverter doesn't work suggests to me that your battery might be bad. You said it has 12.3 volts, but that is under no load. What happens to the battery voltage if you turn on a few 12 volt lamps?

-- Dan Meyer

[Joe MacDonald]

Check all the wiring connections under the front roadside seat.
Disconnect the brake wire from the terminal block and see if your voltage changes.
make sure that there is a ground wire (white ) from the terminal block to the frame.
You don't say if your signals work correctly or not, or your markers,

[Pete Dumbleton]

The wiring on the trailer might be perfect -- How about the wiring on the truck?

The very first thing I would do is run a wire from the truck battery (-) to the ground/return stud on the wiring block, bypassing all the wires, connectors and connections in between to ensure that the return path is good -- Without a good ground/return connection NOTHING is going to work properly and you can chase symptoms all day as the various lights try to get return by going through each other (or through the brake's hot lead, perhaps causing the brakes to energize).

[Don N]

Signals and markers are working...
I have a ground wire from the battery to the frame...
I had my car trailer as well as my box trailer on the truck and all of that wiring worked OK. Have to go back out and dig into it from the start.

[Darwin Maring]

Here is what I do when checking the wiring:

First: I make sure my camper and tow vehicle plug and jack is wired correctly. The right wire connected to the right connector.

Then I take one of those portable battery (Starter) packs and connect the black lead of the starter pack to the camper ground (White wire) of the Plug that connects to the tow vehicle. Note: It is not plugged into the tow vehicle to do this.

Then I take the red lead, connect a probe to it and individually I insert it into the plug to individually test each circuit. Left Turn, Right Turn, Running lights then I connect it to the wire that is to charge the camper battery (Battery disconnected) and test to see if the 12VDC lights in the camper work. Then I disconnect the battery pack and connect the camper battery and see if the camper 12VDC lights work then take a millimeter to test the plug that goes to the tow vehicle to see if I have 12VDC on the hot wire and white ground wire.

Note: The Scamp I have uses the camper frame as the ground and that the white wire is connected to the frame also.

If all reads well then I proceed to the tow vehicle and I use a millimeter to see if each connection of the tow connector is working. One item at a time, L Turn, R Turn, Running lights and the hot wire.

Note: Some tow vehicles will not supply the HOT lead with 12VDC unless the key is on. This is a good thing because should you leave the vehicles connected as on my 2007 Silverado, the tow vehicle battery may run down. I was told on this form that Ford products have a relay that turns the 12VDC off when the key is off.

Foreign Branded Vehicles: Many foreign branded vehicles require a special device to convert their yellow turn and red stoplights to the red turn/stop lights of the American campers.

[Don N]

Whoopee Got my wiring fixed. I had rewired the trailer and tested it all before I decided to replace my axle. Except the axle ended up with replacing the frame as well. When we pulled the shell off the frame, I had to remove the plug on the end to get the wiring out of the frame. When I reinstalled the plug this week, I mixed up the black 12V wire from my truck with the green running light wire, thus powering the markers constantly . I just removed all the wire from my junction box and then started with a test light on the 7 wires that came from the tow vehicle. When I had power at the wrong stud, I realized what I had done. Pulled the plug apart, corrected the wiring and put it all back together. Everything is working correctly now, even the trailer brakes. Thanks all for the replies...