Solar Panel Connect to Battery Through 7 pin plug

RayJim
RayJim Member Posts: 148
in Battery/Electrical & Solar

Anybody hooking up their solar through the 7 pin plug? My solar controller is not detecting the battery for some reason, any thoughts? The battery switch is on position. Solar panels connected directly to the battery works. Could the battery shunt be the problem?

Screenshot 2026-08-21 170155.png Screenshot 2026-08-21 170015.png
2021 T@B Boondock 400. 2021 Toyota SR5 V6

Comments

  • pthomas745
    pthomas745 Administrator, Moderator Posts: 4,637

    What you need to check these sorts of things is a simple multimeter. And, yes, it is possible to charge the trailer battery through the 7 pin plug. Before you start plugging things in that way, the meter will tell you if you have the 7 pin wired properly from the solar controller. You can just start trying it out, but have a handful of 30 amp fuses available if you go that route. There are several Forum threads that discuss using the 7 pin plug for attaching an extra battery, things like that. It can be a good way to do what you want to do.

    Assuming you are trying to connect to the "SAE" port on the trailer? Or some different connector?

    The meter will show you how the "port", of any type, is wired to the battery: which "side" of the port is positive or negative. Once you establish that, wiring the controller to the port is straight forward. The meter will also tell you if the port is even wired at all.

    This is a multimeter (inexpensive at Harbor Freight, etc) that will show you what you need. In the Tabs, You can see the "positive" wire from the battery to the port is on the "top" of this connector, the negative on the bottom. If you look at the SAE cable, the part of the cable "inside the plastic" is supposed to carry the positive output from the solar controller. The "big metal part" is the negative output. Doesn't matter if that "red cable" is on the "negative" output from the controller that has that metal part on it. The meter is the final authority!

    And, of course, there are the "adapters". We can show you how those can be used, also.

    image.png

    You would need to check your 7 pin adapter in your photo also. Not sure if you built that one yourself, or have found it "premade". A quick check with the meter will help you see if the wiring is correct.

    So, find a meter. Figure out the SAE port, or whatever port you happen to have on your trailer. Wire it properly. Trace the positive and negative output from the solar panels, into the solar controller, and do the same thing for the cables out from the controller.

    Take some more photos, we can help with all this.

    2017 Outback
    Towed by 2014 Touareg TDi
  • RayJim
    RayJim Member Posts: 148

    Thank you for taking the time to respond will use a multimeter to check for proper wiring the 7 pin connecter that was purchase online.

    2021 T@B Boondock 400. 2021 Toyota SR5 V6
  • RTWCTS
    RTWCTS Member Posts: 206
    7-pin-RV.jpg

    Don't know if you need this to help with troubleshooting @RayJim, but posted it just in case. Black and white should be path to the trailer battery.

    'Racing the Wind and Chasing the Sun'

    In a 2023 T@B 400 (former T@B 320 owners)

    Relentlessly Pursuing a Silverado EV

    Homeport - Virginia Beach, VA

  • Ikanizer
    Ikanizer Member Posts: 20

    Yes I connect one of my suitcase panels to the 7 pin connector. I also plug my Starlink mini into the charge controller. All you have to do is make sure you wire it up correctly as described in the above comments.

    IMG_0033.jpeg
    2023 400
    2021 F150 2.7l 
  • pthomas745
    pthomas745 Administrator, Moderator Posts: 4,637

    @Ikanizer This is one of the rare uses of the Load outputs in this group. That is a really good idea. What is the power draw of the Starlink?

    2017 Outback
    Towed by 2014 Touareg TDi
  • Ikanizer
    Ikanizer Member Posts: 20
    edited August 24

    @pthomas745 -Starlink mini draws 1.5 - 2.5 amps.

    2023 400
    2021 F150 2.7l 
  • pthomas745
    pthomas745 Administrator, Moderator Posts: 4,637

    @Ikanizer I thought it was pretty light, but that is smaller than I thought.

    How have the Dokio panels and solar controller held up for you? I have suggested them to many owners, since they are so very simple to wire up.

    2017 Outback
    Towed by 2014 Touareg TDi
  • Ikanizer
    Ikanizer Member Posts: 20
    https://tab-rv.vanillacommunity.com/discussion/comment/222804#Comment_222804

    Yes the Starlink mini doesn't use much power. The only drawback with the 7 pin hookup is I have to go outside to turn it off/on. There is a sleep setting but I always seem to set the time wrong when I use it.

    I have 300W and 160W Dokio panels to support my 3x100ah batteries (Battleborne 😱).

    The 300W panel is a little bit too big and flexible and for that reason I don't get it out much. I usually connect that one through a port I installed in the Nautilus bay. I have 4 of the folding metal frames I lean it against.

    The smaller one I've been using for about 2 years and it works fine. It is much easier to lean against the trailer/truck/tree/picnic table. Wind can cause problems. I have left the smaller controller out in the rain a few times and I seems to keep on going. We spent more than 2 months on an Alaska trip this summer mostly boondocking and never had a problem with power.

    2023 400
    2021 F150 2.7l 

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