Disconnect 12volt From Tow Vehicle

cid69
cid69 Member Posts: 25
in Battery/Electrical & Solar
2017 320S....I switched to Lithium battery and want to disconnect the 12 volt feed from the TV into the trailer. My old TV had an aftermarket hitch so it was easy to pull the fuse on the 12v lead on the TV side. Not easily possible to do this on my new to me 2023 Nissan Frontier so I want to disconnect the 12v on the trailer side. The hitch wiring on trailer side goes into a black box on the frame below the exterior storage box....see pic. The black wire should be the 12v feed and attaches where the arrow points. My question is, can I just disconnect the black wire here without any unforseen "gotchyas"?
2017 T@B 320S, 2023 Nissan Frontier, Parker, CO
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Comments

  • AnOldUR
    AnOldUR Member Posts: 1,728
    edited December 2025
    I did the exact same thing a while back and have not had any problems. Solar keeps my LiFePO4's charged while on the road. No worry about disconnecting the 7-pin to prevent tow vehicle battery drain. No conflicting charge profiles between the trailers lithium and the tow vehicles AGM.
    Stockton, New Jersey
    2020 nuCamp T@B 320S * Jeep Wrangler
    60,865 camping miles through the end of 2025

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  • MuttonChops
    MuttonChops Member Posts: 1,940
    cid69 said:
    . . . want to disconnect the 12 volt feed from the TV into the trailer.  
    . . . can I just disconnect the black wire here without any unforseen "gotchyas"?
    As @AnOldUR noted, YES.  Removing the +12V Wire (black) at the junction box will achieve your goal.

    Suggest you fully 'electrical isolate" the +12V wire so it does not cause issues when traveling.
    '18 320 S,  pitched axle, 3020HE; PNW based
    TV: '17 Colorado V6 Z71 4x4, Tow Package, GM Brake Controller
    TV: '25 Canyon AT4
    Adventures:  58   Nights:  405  Towing Miles 50,180
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  • Horigan
    Horigan Member Posts: 864
    edited December 2025
    I think a simpler way would be to pull the fuse on the tow vehicle.  Whether it's an after market or OEM brake control wiring, there should be a fuse for the trailer 12V wiring, and another for the brake controller.  I just pulled the 12V fuse on my aftermarket firewall fuse when I went to lithium.  
    Rich
    2019 T@b 400
    2025 Toyota Highlander 2.4L Turbo
    Bellingham WA
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  • cid69
    cid69 Member Posts: 25
    Thanks, all. I'll disconnect that wire this week. 
    2017 T@B 320S, 2023 Nissan Frontier, Parker, CO
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  • SLJ
    SLJ Member Posts: 646
    edited December 2025
    The BMS on my batteries protects from over voltage charging and my Ford with the factory tow package disconnects the seven pin 12V charging line when the ignition is off. No need to mess with it. Nice to keep the 12V fridge running off the tow vehicle when on the road so the batteries don't drain at all. The Ford supplies around 8A @14.6V while driving so plenty for the fridge. 
    2021 T@B 320 S Boondock
    2025 KZ Sportsmen 130RD
    2025 Ford Ranger
    The Finger Lakes of New York
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