Forum Discussion

GordonThree's avatar
GordonThree
Explorer
Sep 22, 2013

Ram 1500 - 12v power to trailer

I've upgraded my tow from a 290 hp station wagon to a 395 hp truck and it's really made a difference pulling my little Sportsman.

One thing the Ram lacks, and it's minor, is the ability to charge the trailer batteries.

My wagon had an after market trailering package installed, and once I upgraded the ground wire in the car side of the 7 way, it provided almost 30 amps to the trailer. 30 amps isn't huge, a drop in the bucket to my 800 AH battery bank, but still better than nothing.

The Ram, a 2013 1500 "Outdoorsman" (factory 7 way setup and factory brake controller), on the other hand provides a measly 10 amps to the trailer. The gas solenoid on my fridge takes 3 amps, the inverter's electronics on standby takes another amp or so, leaving 6 amps to charge the batteries.

The trailer safety lights all work, and shine brightly. The 10 amps is measured across a precision shunt by the battery management controller which is part of my inverter setup.

Have other Ram drivers noticed a low charge current through the factory 7 way on their truck?

Only mention I find of power supply for the trailer battery is fuse F30, 30 amp, named "Trailer Tow Receptacle". The fuse is intact. I next opportunity I have to fiddle, I will pull it and see if BAT+ goes out on the 7 way.
Tow Vehicles
  • KD4UPL's avatar
    KD4UPL
    Explorer
    Sep 23, 2013
    The only thing that would limit the current is the resistance in the wiring. It sounds like the truck's charge wire is long and small. Changing it out for some larger gauge wire should make a big difference.
  • DougE's avatar
    DougE
    Explorer
    Sep 23, 2013
    On my Chevy van I mounted a small fuse block next to the battery then ran a #6 wire to the fuse block from a side post adapter I added to the battery. Then ran #10 from the fuse block and the first battery ground connection to the trailer receptacle. Fused it at 30 amps.
  • APT's avatar
    APT
    Explorer
    Sep 23, 2013
    10A "charging" is pretty typical for modern TVs. How many hours are you driving that you need to restore 25Ah of net charging given you have 800Ah of capacity?


    IMHO, charge at home, travel and maintain (or slight charge), consume while boon-docking. No need to charge @ high rate while driving.
  • GordonThree's avatar
    GordonThree
    Explorer
    Sep 23, 2013
    APT wrote:
    10A "charging" is pretty typical for modern TVs. How many hours are you driving that you need to restore 25Ah of net charging given you have 800Ah of capacity?


    IMHO, charge at home, travel and maintain (or slight charge), consume while boon-docking. No need to charge @ high rate while driving.


    I'm a heavy user of electricity and would rather use some of the truck's fuel to recharge the batteries while I drive, rather than listening to a generator when I get where I'm going.

    ---

    I'm going to price out having a car stereo shop run a 2 or 4 ga battery cable from the alternator, through a fuse and battery isolator, back to the hitch area, along with a similarly sized pigtail grounded to the frame somewhere near the hitch. Then I can use something like a fork-lift DC interconnect and a similar cable setup on the trailer to connect to the battery bank.
  • APT's avatar
    APT
    Explorer
    Sep 23, 2013
    Why not charge at home before leaving, AC/DC converter you already have? If the batteries are nearly full capacity before you leave, you don't need any "charging" while driving.
  • GordonThree's avatar
    GordonThree
    Explorer
    Sep 23, 2013
    APT wrote:
    Why not charge at home before leaving, AC/DC converter you already have? If the batteries are nearly full capacity before you leave, you don't need any "charging" while driving.


    This is not relevant to the original topic.
  • DougE's avatar
    DougE
    Explorer
    Sep 23, 2013
    GordonThree, I think you're going a little overboard there with wire size. The alternator charge wire is at most 10 gauge. I used 10 gauge for mine with a 30 amp fuse. I guess you could go overkill with 8 gauge but don't see any gain going up to 4 gauge. By the way, the voltage drop of 20' of 10 gauge wire delivering 12 amps is 0.263 volts.
  • APT's avatar
    APT
    Explorer
    Sep 24, 2013
    GordonThree wrote:
    APT wrote:
    Why not charge at home before leaving, AC/DC converter you already have? If the batteries are nearly full capacity before you leave, you don't need any "charging" while driving.


    This is not relevant to the original topic.


    You can ignore my comments, but you are creating a solution to a problem that does not exist IMHO, all the while spending your money to do so. Think outside your box.
  • wanderingbob's avatar
    wanderingbob
    Explorer II
    Sep 24, 2013
    I do not think that you have a problem ! My Dodge keeps my TT batts right where they ought to be . Maybe you are trying to charge while idling at your campsite , that may be a problem .
  • frank_henn's avatar
    frank_henn
    Explorer
    Sep 24, 2013
    If it has a factory tow package pull the top off of the fuse box under the hood and put a fuse in the spot that says trailer this wil enable your truck to charge the battery

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