Upgrading a Trailer From a 4-Way Flat To a 7-Way Connector For Adding an On Board Battery

Updated 02/06/2023 | Published 02/04/2023

Products Featured in This Question

Trailer Wiring Junction Box

(823)

$34.63

Pollak 7-Way to RV Socket LED Circuit Tester - Vehicle End

(156)

$42.78

Hook Probe Circuit Tester

(65)

$13.35

Question:

I have a utility trailer with basic four wire flat connector with two brown so five in total. I want to change to 7 pin blade and run a lead with all the wires into the trailer to not only power the lights around the trailer but also provide 12 volts to a deep cycle battery someday. Is the 12 volt blade coming off the truck able to provide charging voltage to top off the deep cycle battery while driving. Is the 12 volt blade in the 1 oclock position powered all the time or switched on/off with truck running or sitting. I am considering the Bergman 7 way product you sell. Thanks

asked by: Bruce

Expert Reply:

For your trailer I recommend the Junction Box # 38656. This will allow you to add the Wiring # HM20048 as needed inside the junction box. I have added an image below showing the wiring terminal positions for the 7-way. Depending on your vehicle your 12 volt power may run all the time or only when the ignition is turned on. You can use a Tester # PK12741 to check all your circuits or a Test Light # PTW2993 to check each circuit individually. The charge line will be able to recharge your trailer battery.

expert reply by: Bud M