Truck wiring to charge camper battery?

Discussion in 'Power - Site Power/Batteries/Generators/Solar' started by Allan Unger, Nov 13, 2019.

  1. Allan Unger

    Allan Unger New Member

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    I have a 2007 Tundra with a 150 amp alternator. The camper is a 1994 Scamper PUP. I want to wire the truck to charge the camper battery (there is no battery currently installed on the camper). What is the best place to locate the battery in the camper? What gauge cable should I use? What is an appropriate isolation solenoid to use for this configuration? Appreciate any responses!
     
  2. Raycfe

    Raycfe Waterford Ct.

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    Usually on the tongue of the camper. Too much weight in the rear leads to sway. 10 gauge wire.
     
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  3. rabird

    rabird Howdy!

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    Check your Tundra for an existing charge line!

    I used a 40A 'short stop breaker' (auto parts store) @ the batt+, 10g (8g would be better), plastic loom to protect the wire and zip ties to keep it in place along the run to the rear.

    I found a fuse holder (hot with ignition) not being used (sun roof), added an 'add a fuse' and wired a relay to turn on/off with the key. With the add a fuse you can add a circuit to almost any existing fuse.
     
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  4. Anthony Hitchings

    Anthony Hitchings Active Member

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    There is a lot of info on your questions on this site and on the web, especially discussing wire gage. Isolation solenoid is an essential part of the system.
     
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  5. Anthony Hitchings

    Anthony Hitchings Active Member

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    Since you asked about wire gaqe, let me toss this out to the active readers, purely as an FYI. A while back I bought the OEM 7-pin harness for my 200 Jeep Liberty. I have not installed it. I have looked it over a few times, and the wire gages are quite small, even the largest is nothing close to 10 GA, or even 12 Ga. Its most surprising. Ditto the wire gage on the back of the "cigarette lighter" outlet on the front dashboard. Heading in the opposite direction, the alternator on my 1969 Chevy V8 was 55 Amps, the alternator on my 2008 Liberty is 140 Amps. Loads are the same being engine, lights and AC unit.
     
    Last edited: Nov 13, 2019
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  6. GreyFox

    GreyFox Well-Known Member

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  7. tombiasi

    tombiasi Well-Known Member

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    Some people think they need a very large gauge wire to charge the battery. You only need the same gauge as the OEM charge line. Maybe if you were going to run the line a hundred feet you would need heavier wire.
     
  8. Anthony Hitchings

    Anthony Hitchings Active Member

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    My guess is that there are two scenarios for a TV charging the Pup's battery:

    1) Maintaining charge or light charging of the PUP battery (PUP voltage is not low) - smaller gage is ok, voltage drop in the charging line is not too big a deal

    2) largely depleted PUP battery - you either need heavier wire gage to minimize voltage drop or get a longer charging time - but be careful of overheating the wiring or connectors in the TV. Auto alternators are designed for auto use (voltage-wise) , so they likely won't offer as much voltage to your depleted PUP battery as a stand alone or PV charge controller, this situation, to a degree, limits the current (as current = function of voltage difference) in the charging line from the TV. Which is likely why some folks say you can't run the 3-way frig and recharge a depleted battery at the same time while towing a PUP.
     
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  9. rabird

    rabird Howdy!

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    OEM 16g is not adequate. Voltage drop is the issue over 20 feet or so even at 10A.

     
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  10. tombiasi

    tombiasi Well-Known Member

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    Vehicle alternators are not designed to charge a dead battery, they are designed to maintain them.
     
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  11. tombiasi

    tombiasi Well-Known Member

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    Do you know of a vehicle that uses a 16 Ga. charge line? If so 8 Ga. wire after that will do no good.
     
  12. rabird

    rabird Howdy!

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    Yes, my 2015 ford truck, wired just like the '16 in the video. One does not use the dinky charge line, one rewires with ample size wire all the way to the battery.

    On my S-10 with no charge line I added as stated above, the 4 to 7 blade adapter did have 10g wire for Aux, 12v- chassis common and 12v+ charge line.
     
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  13. tombiasi

    tombiasi Well-Known Member

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    Surprised to hear that but I do agree with your solution.
     
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  14. Econ

    Econ Active Member

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    IF, you believe in operating the 3 way refrigerator on 12 volt while traveling, The charge wire on most is too small to supply enough to keep from depleting the camper battery. If, you come over and join the dark side, you can use propane. Join the dark side, we have candy.<GG>
     
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  15. Allan Unger

    Allan Unger New Member

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  16. Allan Unger

    Allan Unger New Member

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    After some more research, I found that my factory 7pin connector has a 30A, 12V Pin. Would this be adequate to supply voltage to the camper battery, provided that the wire is at least 12 ga?
     
  17. tombiasi

    tombiasi Well-Known Member

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    For 30 Amps you should use 10 Ga.
     
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  18. GreyFox

    GreyFox Well-Known Member

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    Regardless of wire gauge your vehicle will never be able to fully charge a discharged deep cycle battery as it's incapable of supplying an adequate bulk charging voltage of at least 14.4 volts and for a sufficient length of time - it was never designed for this purpose. The solution, as I mentioned earlier, is to equip the vehicle with a DC > DC charger which is specifically designed to overcome this issue.
     
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  19. tombiasi

    tombiasi Well-Known Member

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    True.
     
  20. rabird

    rabird Howdy!

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    Yes, that will work as well as many others. No it will not fully charge a battery. I know nothing of you computer's way of regulating alternator voltage, but you should get some charge to the battery just don't expect too much!

    So add a battery tray to your tongue, add a battery, wire the batt+ into the trailers 'charge line' that goes from the trailer/TV connector to the back of the power center, fuse this at the battery, wire the 12v- to chassis common IE the frame of the trailer (certainly not earth ground). Buy a few feet of 10g in red or black for the + and white for the -.
     
    Last edited: Nov 13, 2019
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