How Much Power Should I Make Available To Charge My Trailer Battery

Question

Question:

I have installed this kit onto my trailer. Now Im installing a seven pin connector to the RV that will be pulling it. The RV doesnt have any wiring in place yet. For the black power supply 12 volt wire, how much capacity should I give it to charge the battery? I will be wiring directly from the RV engine battery and will be putting a circuit breaker or fuse close to the batteries. What size breaker or fuse should I ? I would like to use 12 gauge wire or smaller for the run.

asked by: JD

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Expert Reply:

You will have to use 10 gauge wiring, part # 10-2-1, because the wiring run you need will be longer than 25'. You will also need to install a 4-way connnector on your motorhome before you are able to install the 7-way connector. The Upgraded Heavy Duty ModuLite Circuit Protected Vehicle Wiring Harness with Installation Kit, part # C59496, will work for your motorhome. Once you get this installed, you can install the Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires, part # ETBC7, you will get a 20 amp, 30 amp, and 40 amp circuit breaker with the kit. The 40 amp circuit breaker will go between your RV battery and the 12V hot lead of your 7-way connector. You will use either the 20 amp or 30 amp to go between the battery and your brake controller, if you install one. Your setup will not provide amperage to charge your RV battery.

I have included product description links, a weblink to wiring your vehicle with a 7-way connector, and video review links below.

expert reply by: Mark Smith

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Recommended Wire Gauge For Length Of Run
(click to enlarge)

Answer 1

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 2

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 3

If you just need a 4-pin to 7-pin trailer wiring adapter, then you can use part #C57672. This will plug into the 4-pin trailer connector on your brother's vehicle and give him the 7-pin socket for the trailer. Keep in mind, this will only…

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Answer 4

When wiring a trailer connector, it is best to wire by function, as wire colors can vary. We have an excellent wiring diagram on our website, I will provide you a link so you can look at it. If you are looking at the inside of the trailer connector…

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Answer 5

The only difference between 7-Way Utility and 7-Way RV is the color of the wires. The pin outs are the exact same so either would work just fine with the other. If you check out the picture I attached you'll see that the functions are all the…

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Answer 6

Since wire color codes are NOT universal, we always recommend wiring by function, rather than wire color. If you look at the Trailer Wiring FAQ article I have linked you to, you can see some diagrams showing the proper way to wire a vehicle and…

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Answer 7

It's a wire color difference but not a function difference on the pins of the 7-way. The difference comes from the fact that the two different styles are representative of two different areas that uses trailers. Traditional is usually seen on…

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Answer 8

It could be a tow package fuse on the vehicle. Use the owners manual to find the locations of fuses/relays related to the tow package wiring to check them and replace as needed. If the issue is not a fuse or relay then you can test the vehicle side…

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Answer 9

On a 7 pin round which is the common connection on a semi trailer, the clearance/marker lights are at the 10 o clock position when you look at the trailer wiring connection. When looking at the connector on the back of the truck, that will put the…

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Answer 10

You have it right so far, the 4-way connector is just as you have stated. Remember that Yellow has a L in it so that is the left side brake/turn signal and green has a R in it so that is the right side brake/turn signal. The colors for wiring a 7-way…

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Answer 11

On a 7-Way connector the suggested minimum wire gauge for the White (ground) wire, the Red or Black (power) wire, and the Blue (brake power) wire is 12 gauge. The minimum wire gauge for the remaining Green (right turn/brake) wire, the Yellow (left…

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Answer 12

You can certainly add a 7-way trailer connector to your trailer with 6 wires. You would simply have 1 pin on the 7-way connector that did not function. I recommend adding a 7-way molded trailer wire connector like part #H20046, and a junction box…

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