What Should the Voltage Be At Trailer Battery Charge Line Circuit on 7-Way
Question:
I was told that when towing my camper trailer the automobile would charge the camper batteries through the 7 pin plug. The voltage at the seven pin plug maxes out right at 12.25 V although measuring the voltage at the cigarette lighter inside the automobile shows as much as 14.25 V when initially charging the automobile battery. The 12.25 V is insufficient to cause charging of the RV batteries. The plug was wired by an automobile dealership. I suspect he wired the red wire incorrectly. Where should the red wire be connected?
asked by: Dan C
Expert Reply:
In regards to the battery charge line circuit, the exact voltage will vary from vehicle to vehicle and the state of the battery but it should be anywhere from 12 to 14 volts. That said, you'll lose voltage the more resistance you have between the power source and since the trailer connector is at the rear and the battery is at the front, you're likely going to be on the lower end of the somewhere closer to 12 volts. This will still work great to keep your trailer batteries topped off but the circuit in general isn't really designed to charge a large battery or battery bank. For this, you'll need an actual charge separate of the circuit like the Redarc In-Vehicle BCDC Battery Charger part # 331-BCDC1225D.
Product Page this Question was Asked From
Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp
- Battery Charger
- Battery Charger
- RV/Camper
- Trailer
- 75 Ah
- 200 Ah
- Charges/Maintains
- 12V
- Solar Panels to Auxiliary Battery
- Vehicle Battery to Auxiliary Battery
- Redarc
more information >
Featured Help Information
Instructions
Continue Researching
- Shop: Roadmaster Battery Charge Line Kit for Towed Vehicles
- Q&A: Recommended Charge Line For Jeep Battery Using Brake Buddy Supplemental Braking System to Flat Tow
- Q&A: Full 12 Volts Not Reaching Roadmaster Battery Charge Line Kit for Towed Vehicle
- Shop: Roadmaster 4-Diode Universal Wiring Kit for Towed Vehicles - 7-Way to 6-Wire Hybrid Cord
- Search Results: tow bar wiring
- Shop: Vehicle Tow Bar Wiring
- Shop: Hopkins Multi-Tow Trailer Connector Adapter - 7-Way to 5-Wire Flat/4-Wire Flat and 12-V Power Socket
- Shop: 12 Volt Outlet with Waterproof Cap - 10 Amp - Black
- Shop: Furrion RV Tankless Water Heater - Gas - Automatic Pilot - 60,000 BTU - 16" x 16" Door
- Shop: Pollak 7-Way to 12 Volt Power Outlet Adapter
- Shop: Furrion RV Tankless Water Heater - Gas - Automatic Pilot - 60,000 BTU
- Video: Pollak 7-Way to 12 Volt Power Outlet Adapter Review
- Video: Pollak Wiring - Wiring Adapters - PK11896 Review
- Q&A: Recommended Adapter to Plug Portable Air Pump into Trailer Connector
- Video: Choosing the Right Trailer Wiring
- Q&A: Choosing Between the Brake Buddy Select 3 and the Blue Ox Patriot Supplemental Braking System
- Search Results: rm~88400
- Shop: Base Plate for Tow Bar
- Article: Trailer Wiring Diagrams
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Video: Roadmaster Tow Bar Wiring - Splices into Vehicle Wiring - RM-15267 Review
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Shop: Trailer Wiring
- Search Results: tow bar
- Q&A: What is the Difference Between a 4-Way and 7-Way Trailer Connector
- Shop: Trailer Hitch
- Search Results: base plates
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Video: Roadmaster Battery Charge Line Kit Review
- Shop: Vehicle Tow Bar Brake System