Solution for Charging Auxiliary Trailer Battery Through Truck's 7-Way Connector

Question

Question:

Hello! So i have been putting together the supplies ill need to wire up my 6x12 enclosed moto hauler/camping/work trailer. So far, I have a blue sea systems fuse block and a manually operated relay switch. I am going to pickup a 12V battery and extrerior mount box shortly. My questions are in regards to connection to the trucks main battery through the 7 pin connector. Currently, the trailer only has brake and running lights. I am planning to add lighting, 2 solar panels and charge contoller, a couple of usb ports and maybe setup for a in fan and dc powered fridge. I understand the operation and wiring up of the fuse block and load souces downstream but I need guidance getting from the trucks main battery to the aux battery through the current 7 pin connector.

asked by: Brent

0

Expert Reply:

In order to activate the 12V circuit on your truck's 7-Way so that you can maintain the charge on the trailer's auxiliary battery, you just need to run a length of 10 gauge wiring like # 10-1-1 (sold by the foot) through a breaker like # 9510 from the truck battery's positive post to the 12V pin on the 7-Way. This is the pin located at the 1 o'clock position (or 11 o'clock when looking at the backside/inside of the connector). Then from there you would wire the corresponding pin on the trailer's 7-Way to the auxiliary battery.

It's important to keep in mind though that this type of setup is only good for maintaining the charge on the trailer's battery, meaning it likely won't provide enough amperage to actually charge it up from a depleted state.

For the type and amount of accessories you're looking to power from the auxiliary battery, I'm wondering if a better option will be with a DC to DC charger like the Redarc # 331-BCDC1240D. This on-board system will actually boost the charge from the truck's battery so that you can charge up the battery during travel, ensuring that it's ready to go whenever you stop for work or play.

Redarc recommends using the 60-Amp MIDI Fuse Kit # 331-FK60 for protection and the Quick-Connect Set # BDW20047 will work perfect for creating simple plug-in connections.

I have attached the full installation guide below, along with a comprehensive video so you can see exactly how everything would be wired.

expert reply by: Chris R

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Answer 1

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Answer 2

You would not be able to charge your battery through the wiring on your 4-way trailer connector. Since your truck has a 7-way connector, you could maintain the power to the battery but not charge it. To begin, you would need to cut off your 4-way…

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Answer 3

Typically the black wire on a trailer 7-Way like the Hopkins #HM20048 is for 12V power. It will run from the positive battery terminal on your tow vehicle back to your trailer battery or whatever you're needing to power (like interior lights).…

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Answer 4

The only pin that should be continuously showing 12V power on the 7-Way connector on your vehicle is the 12V power circuit which is normally the black wire but not always. In 7-way wiring the 12V auxiliary power feed is carried on the contact at the…

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Answer 5

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Answer 6

Hey Michael, it actually sounds like the battery in your Wrangler is the issue. If it was holding a charge just fine when you first started towing and nothing has changed yet it's now dead when you stop that to me would indicate the battery is on…

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Answer 7

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Answer 8

You can put a maintenance charge on your trailer battery with the 12 volt accessory circuit of the 7-way. The 1:00 position of your 7-way carries this circuit. You would just need to run a length of 10 gauge wire like part #10-1-1 (sold by the foot),…

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Answer 9

I recommend a 12 volt car battery rather than a breakaway battery because you may end up needing the larger battery down the road. What you will do is attach a battery box (see link for options) to the trailer frame. From the trailer side 7-Way…

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Answer 10

The auxiliary 12-volt wire that runs from the 7-way connection to 7-way trailer plug will supply 12-volt power from the vehicle to the trailer. The 12 -volt power will allow interior or exterior lights to run that are not wired in to the…

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Answer 11

First it is important to know that the battery on the Engager break away kit #20099 will only be charging as long as the 12 volt circuit is providing power. If you shut off the vehicle and disconnect the trailer it will not be charging. When there is…

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Answer 12

Hey Gary, For the wiring you'll need the Roadmaster Diode 7-Wire to 6-Wire Flexo-Coil Wiring Kit #RM-15267. This will transfer your motorhome's traffic signals to the tail lights of your Bronco. If you find that you have variable voltage tail…

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