Home Forums Truck Camper Adventure Forum 7 way charge line saga

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    • #37041

      I thought others who are considering using the factory charge line that runs into a seven way trailer bumper hitch might be interested in this story.

      I have a ’06 Duramax with factory trailer wiring.
      I’ve had four campers on this truck, all using the factory charge line to the bumper for battery charging. One camper was installed at the factory, where the owner said no problem to use factory hitch charge line; they used a line off the back of the pop up, to the bumper socket.

      Currently I have a canopy on my truck and some lighting and other little (<3amps) pulling on that charge line. Well I started to see flickering lights. I saw voltage all over the place, but eventually stabilizing at 12.7 volts. When I tried to draw more than an amp out of the charge line, voltage would drop below 10 volts.

      I concluded connectors or 7 way plug or Y to bed mount plug were bad. Well I tested all that and they were fine. So my issue was in the factory wiring. I was surprised to see this line is protected by one 60 amp fuse… and guage seemed to be pretty stout on the charge line (12?). Plenty to send a few amps back to the camper or canopy.

      I took truck to dealer explained situation…they punted. They could only test voltage with no load at the bumper. Said it was fine. They could not tell me how many amps you might reasonably draw off the 7-way charge line.

      So I concluded at one point or another I probably pulled alot of amps through that charge line to try to charge a couple of deeply discharged batterys in a camper…a very common situation…and burned up the charge line. Note I checked the grounding. It was fine.

      I clipped the line into the bed mount and ran an new 8 gauge wire protected by a 30 amp fuse from the alternator to that plug. It took longer than I would have thought. Things working now.

      I concluded Lance was right. Do not use factory charge line or even seven way plug for any kind of serious amp draw.

      Any thoughts?

    • #38060

      Given this does not seem to be a commonly reported problem, I am not sure what to make of it. I have had zero charging or related issues with either my past Hallmark or my current NorthStar. Speaking as retire RV tech, normally when I see drops like that under minimal load I expect to find a corroded or loose connection. Measuring amperage is often more helpful is diagnosing this type of problem as if it was a connectivity issue, replacing the entire line would have eliminated any such problem if it existed.

      Although I know Lance favors heavier charge lines, the appliances and amp draws are common to a multitude of TCs which do not seem to be reporting similar issues.

      Just my thoughts.

      Steve and Andra
      2012 F350 6.2 gasser SRW LB
      Fab Fours front and rear in case we run into a rhino
      2019 Northstar Laredo SC

    • #38070

      Just my 0.2 cents from afar. Based on your findings insofar as the charge line (I presume OEM?) from the alternator to the 7 pin connector is protected by a 60a fuse, this might suggest that a serviceable 7 pin connector is good for 60a (or slightly more), and it also might suggest that the camper’s batteries were quite heavily discharged (likely near maximum current receptivity)…

      Bad connections (which add even more resistance) may have been downstream of the protective fuse, while contributing their fair share of additional resistance, culminating in a ‘Perfect Storm’ making matters worse…

      My guess is that both your alternator and charge line were under an fair amount of a load for an extended time…Just Saying


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