How to Wire a truck to Charge a Camper Battery

Discussion in 'Power - Site Power/Batteries/Generators/Solar' started by lightfoot, Sep 16, 2011.

  1. lightfoot

    lightfoot New Member

    Dec 22, 2009
    just bought a 1990 Toyota pickup, how can I wire a 6 or 7 pin connection to my truck to receive the existing 6 or 7 pin connector on a pop-up camper so it will able to charge the camper battery when driving?
    Thanks in advance!
  2. dackley

    dackley 1999 Jayco Heritage Laurel with popout

    Dec 24, 2010
    There are two ways one costs more money and time, the best wat is to buy an isolator, inline fuse, 1o gauge wire. The isolator goes between the alternator and battery, keeps battery in vehicle from ever being discharged by camper, fuse goes in line to camper near isolator, 10 gauge goes back to 7 pin connector. second way to do it is hook 10 gage directly to battery, then fuse near battery, 10 gauge back to the 7 pin. Second way will kill the tow vehicle battery if camper is left plugged in to it when camping.
  3. smoreking

    smoreking Member

    Sep 15, 2009
    Small Town, Middle TN
    I bought a 7 pin plug for my Ford that had a harness on it to connect at the frame of my truck replacing my old 4 pin connection. The only other thing I had to do is add a relay or some type of fuse into fuse box under hood. Very easy with no cutting or splicing. had the kit and online video instruction.
  4. robctry69

    robctry69 New Member

    Jul 24, 2011
    i put a switch and relay on mine so i would have full control of it
  5. marcham

    marcham New Member

    Aug 2, 2011
    +1 for the switch and relay. Your vehicle being 1990s vintage, the alternator probably has a few fixed voltage output points. If you use a battery isolator, it will cause a voltage drop in both batteries and thus your vehicle's battery will never be fully charged.

    If you use a relay, then there is virtually no voltage drop associated with the device. I wired mine so that whenever the vehicle's position lights are on, there is power to the trailer. Make sure you use a relay that's rated for constant-on.

    Another item to keep in mind is that unless you run some rather large wires to the trailer, you won't get much of a charge. I ran 26' of 10 gauge and my battery takes at most 3-4 Amps, which is not enough to run the DC refrigerator (10A), but is enough to keep the battery charged and top it off a little while driving. It also helps keep a charge on the battery that runs my brakes should the trailer disconnect.
  6. johnsagraves

    johnsagraves New Member

    Feb 1, 2010
    I used one of those cigarette lighter chargers where you plug one in your cigarette lighter and other in another car lighter to charge your battery when dead. I added a cigarette lighter adapter to my battery in the PUP and cut and hooked it up through my 7 pin plug. If that makes sense. I did find that it did not provide enough electric to keep my fridge running without drawing current from the battery (depleating the battery), i but it did help reduce the draw on the battery making it last longer. John.
  7. studio960

    studio960 New Member

    Nov 27, 2010
    I think Lightfoot just wants to know how to wire the connector for the pup connector to get power only while driving. Shouldn't need any isolator, etc if only drawing while plugged in and driving.

    I found a wire diagram online for the connector poles but you can probably just use a test probe to see which pin is the battery plus pin on your pup. Then match up which pin (wire) needs to be the supply power from your truck. Your biggest problem then is finding a hot lead near the rear of your truck to attach to the truck side connector (receiver) power pin. You may have to run a wire from the engine compartment.
  8. marcham

    marcham New Member

    Aug 2, 2011
    And don't forget to fuse it close to the battery. The reason for the relay is that in the event you park your vehicle with the wiring plugged in, you wouldn't want to desicharge the car's battery. Most trucks that come pre-wired for a 7 pin will use the ignition to turn on/off 12VDC power to the 7 pin connector. For a retrofit, it's easier to use the position lights ( brown wire ) to switch the 12VDC from the battery.
  9. Raycfe

    Raycfe Waterford Ct.

    Oct 3, 2007
    Waterford, Ct
    [​IMG] from Connecticut, happy camping, enjoy.

    Simple ...... 10 gauge wire, 30 amp circuit breaker, terminals and wire ties. Mount the 30 amp breaker with a short piece of 10 gauge to the positive battery terminal of the TV (tow vehicle), then run a 10 gauge wire form the breaker to the 7 pin at the rear bumper. You will need to position and secure this wire away from the exhaust etc.
    If more info is needed ..... please ask away ........
  10. austinado16

    austinado16 Proud Starcraft Owner

    Jun 9, 2007
    Since you're running wire, just run 8 gauge and be done with it. Fuse it near the battery. It'll go to position #4 on the 7pin round Bargman.

    Also, make sure that the white ground wire on that same Bargman is at least 8ga. If it's not, replace it. Same rule goes for the ground on the camper's 7pin.

    Think of electrical current as water flowing through pipes. Run big pipes and you can get a lot of flow. Run small pipes and you get a lot less flow, and a lot of electrical, that means heat.

    So run it all in 8 gauge, and fuse it up at the battery with a 30amp fuse.

    It WILL be plenty enough power to both charge the camper's battery and run the camper refrigerator on the 12vDC setting should you choose to run the fridge that way. We do this all the time. I have a remote temp sensor in my fridge, and one of those weather stations that I keep up on the cab while towing. Our fridge actually drops in temperature the longer we're on the there's plenty of power being sent back......and that's with dual air conditioners running, and sometimes manditory headlights on during the day.

    I recently had a little situation with a resetting circuit breaker that's making me change my tune about using them. Had one on the cigarette lighter socket that we use to power things while driving. I pushed a power connector to something into it, the lighter socket failed and started to dead short. Guess what....the resetting circuit breaker kept turning the power back on! So about every second I had a loud crackle, followed by sparks and smoke coming out of the lighter socket. I had to quickly pull over and start yanking wires from the back of the socket because I couldn't get to the circuit breaker. It was kinda scary there for a minute, and I'm glad I was driving, and not my wife......may have cost us the Suburban.

    Regarding whether you relay the 8ga or not. Mine isn't and I've never had an issue. a) No one stays plugged into their camper while they camp. b) Having the camper plugged into the truck, while nothing is "on" in the camper, isn't using any battery voltage. c) Let's say you left the camper plugged into the truck, and the fridge on 12v and wandered off. It'll take 3-4hrs for the fridge to drain the camper battery, so you've got longer than that since the batteries are working together.

    So whether you relay it or not is up to you, but not relaying it isn't putting you at any risk for killing the truck's battery.

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