Parts Needed for Adding a Charging Circuit for a Trailer Battery while Towing with a 2008 FJ cruiser
Question:
Hi, Have converted from 4 pin to 7 and everything is working fine. Question is, is all I need is #10 wire and inline circuit breaker? Do I have to do anything at the fuse block on the Fj? and Will the in-line circuit breaker prevent my truck battery from being run down? or do I need something to prevent drainage?
asked by: dana
Expert Reply:
You have it figured out. You will need an appropriate length of 10 Gauge Wire, item # 10-1-1, and a 40 amp circuit breaker, item # PK54540, to provide 12 volt power to the trailer connector at the rear of your FJ. This will provide a maintenance charge to the trailer battery while towing the trailer. You will not need to make any changes at the fuse block on your vehicle. The 12 Volt power wire connects to the number 4 position inside your 7-way connector, see the photo in the trailer wiring diagrams FAQ linked here.
The power wire is connected from the trailer connector to the Auxilliary side of the circuit breaker and from the Battery side of the circuit breaker to the positive terminal of the vehicle battery. You should remove the ground cable from the vehicle battery before connecting the power wire from the circuit breaker.
The inline circuit breaker will protect the vehicle and trailer from any type of short circuit or power surge that may occur, but will not isolate the battery from the trailer connection when the the trailer is connected to the vehicle. Most people simply unplug the trailer from the back of the vehicle when they get to their camping destination, to keep the vehicle battery from being discharged.
We do offer the Battery Isolation Solenoid, item # PK5231201, which will shut down the connection from the vehicle battery to the trailer connector when the vehicle ignition is off. It would be a good idea to install the battery isolator if you plan to leave the trailer connected to the vehicle for extended periods, when the vehicle is not running. The isolator also installs inline with the power wire to the trailer connector. You will need a switched ignition source to attach to the 12 volt source on the isolator and the isolator needs to be mounted to the vehicle chassis for a ground connection.
Products Referenced in This Question
Starter Solenoid - SPST - 12 Volt - 100 Amp - Continuous Duty - Grounded
- Accessories and Parts
- Battery Boxes
- Switches and Solenoids
- 100 Amp
- Pollak
more information >
Pollak Circuit Breaker - Cycling/Automatic Reset - 40 Amp - Straight Mount Bracket
- Accessories and Parts
- Wiring
- Circuit Breaker
- 40 Amp
- Pollak
more information >
Product Page this Question was Asked From
Adapter 4-Pole to 7-Pole and 4-Pole
- Trailer Wiring
- Wiring Adapters
- Multi-Function Adapter
- 4 Flat
- Plug and Lead
- 4 Flat
- 7 Round - Blade
- Hopkins
more information >
Featured Help Information
Miscellaneous Media
Continue Researching
- Shop: Timbren Axle-Less Trailer Suspension - Heavy Duty - Long Spindle w/ 4" Lift - 4 Bolt - 2.2K
- Video: Curt T-Connector Vehicle Wiring Harness Installation - 2023 Hyundai Tucson
- Shop: etrailer Electric Trailer Brakes - Self-Adjusting - 10" - Left/Right Hand Assemblies - 3.5K
- Shop: Timbren Axle-Less Trailer Suspension - Heavy Duty - 4" Lift - 4 Bolt Flange - 2,200 lbs
- Search Results: axleless spindles
- Shop: Timbren Axle-Less Trailer Suspension - Heavy Duty - Long Spindle w/ No Drop - 4 Bolt Flange - 2.2K
- Q&A: Should Lighter Off-Road Trailer Have Brakes Added
- Q&A: Timbren Axle-Less Suspension System For A Homemade Overlanding Off Road Trailer
- Q&A: Timbren Axle Less Kit for Trailer that Can Use Toyota 6 Lug Bolt Pattern
- Shop: Brake Mounting Hardware Kit for 7" and 10" Brake Assemblies
- Shop: Trailer Wiring
- Search Results: max coupler
- Search Results: swivel hitch
- Shop: Adapter 4-Pole to 7-Pole and 4-Pole
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Video: Hopkins 4-Pole to 7-Pole and 4-Pole Adapter Installation - 2018 Chevrolet Express Van
- Search Results: hitch extender
- Search Results: etbc7l
- Search Results: hitch stabilizer
- Search Results: lug nuts 1 2 20
- Article: Trailer Wiring Diagrams
- Article: Brake Controller Installation: Starting from Scratch
- Shop: Roof Rack
- Q&A: How to Determine if Vehicle Has Smart Alternator for Using REDARC Battery Charger
- Shop: Brake Controller
- Video: Trailer Wiring Harness Installation - 2013 Mazda CX-9
- Q&A: Adding an In Line Fuse to a 12 V Power Lead from a Vehicle Battery to a Trailer Connector
- Article: How to Charge a Trailer Battery While Driving: 3 Common Problems (And How to Fix Them)
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)