Can I Charge My Trailer Battery Using 7-Way Trailer Connector on Truck
Updated 02/28/2024 | Published 09/18/2011
Products Featured in This Question
Question:
My truck is equiped with a 7 way plug. Is there any way I can use one of the leads to charge a battery in my trailer? Currently, the trailer has a flat four plug that I connect to the truck using an adapter. Any help is appreciated. Thanks,
asked by: Dennis P
Expert Reply:
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 trailer connector and install a 7-way connector on the trailer like the Optronics 7-way, part # A7WCB. You would need to connect the appropriate wires. White is ground, Yellow is left turn and brake, Green is right turn and brake, and Black is the hot lead that you will tap into later. If your trailer does not have brakes or reverse lights you would not connect these pins (see picture).
To maintain power to the battery, you would need to run a wire from the positive terminal on the trailer battery to the power wire on the 7-way. I would recommend using 10 gauge wire, part # 10-1-1, and connecting to the Black wire on the trailer 7-way, or the pin in the 11 oclock position when looking at the front of the connector to the positive battery terminal (see FAQ). You would then connect the negative terminal to a clean metal surface on the trailer frame for a ground connection.
I have linked an FAQ on wiring and a diagram showing the wiring pin out for the trailer side 7-way.
Rich B.
7/8/2020
On a 2011 Pilot does the 7 Way also control the trailer brakes on a 2020 RP-190 travel trailer?
Chris R.
7/13/2020
Featured Help Information
Miscellaneous Media
Continue Researching
- Shop: Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp
- Shop: Trailer Wiring
- Shop: Trailer Hitch
- Q&A: How to Charge a Trailer Battery Through a 7-Way Connector
- Shop: Brake Controller
- Article: Trailer Wiring Diagrams
- Video: All You Need to Know About the Redarc In-Vehicle BCDC Battery Charger
- Shop: Vehicle Tow Bar Brake System
- Shop: Gooseneck Hitch
- Shop: Vehicle Tow Bar Wiring
- Shop: Base Plate for Tow Bar
- Search Results: trailer hubs and drums
- Search Results: dc to dc battery charger
- Search Results: trailer lights
- Search Results: lug studs
- Shop: U-Bolt Kit for Mounting 5,200-lb to 7,000-lb, Round Trailer Axles - 7" Long U-Bolts
- Search Results: helper leaf springs
- Search Results: helper springs
- Search Results: rear sway bars
- Shop: Roadmaster Battery Charge Line Kit for Towed Vehicles
- Shop: OptiMate Smart Battery Charger - DC to DC - 12V - 2 Amp
- Shop: Dometic PerfectPower Battery Charger - DC to DC - 12V - 10 Amp
- Article: How to Charge a Trailer Battery While Driving: 3 Common Problems (And How to Fix Them)
- Shop: Roadmaster 4-Diode Universal Wiring Kit for Towed Vehicles - 7-Way to 6-Way Coiled Adapter Cord
- Shop: Blue Ox Patriot Portable Flat Tow Brake System - Proportional
- Q&A: How to Wire 12V Battery in Enclosed Trailer to Power Trailer Lights Independent of 7-Way Connection
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Video: Review of the Redarc In-Vehicle BCDC Trailer Battery Charger
- Video: A Closer Look at the Demco Trailer Stake Pocket Spare Tire Mount with 4" Offset
- Video: Review of the CargoSmart X Track Trailer Shelf Bundle
on Custom Fit Vehicle Wiring
Sean D.
6/19/2020
i want to do the same. my trailer has a 7 pin and a brake box. i want to use battery for lights and usb charging at the track. i just want the TV to charge the trailer battery while we are traveling and not drain the tv battery while we are parked