Can you Use Hitch Power (4 pin or 7) to connect FWC for charging?

[BBZ]

Curious if there is a way to do this? Just want to add a way of trickle charging while driving without adding an isolator?? Is it possible? recommended or not? Why?

We have a set up that only power used is for led lights and fan, doesn't use much power. Spent 3 weeks in Baja and set up very small solar charger twice. Got home and had 50% battery life. Would be nice to get a little charge while on the road...

 

[OffTheGridMaps]

I can't speak to your setup, but I have a 2003 Tundra that I could charge the batteries using a 7-pin connector as we drove. I just had a local RV shop set up extend the wiring and change it from a 4-pin (original) to a 7-pin. Even at that age, the trailer charge was isolated from the main vehicle battery.

 

[esimmers]

Interesting idea: Charge camper battery while driving by using the truck's RV style trailer plug wiring. That's basically what people are doing when they tow an RV trailer, but there are several things to keep in mind.

First, what's your source of power? You need a plug receptacle on your truck with a 12V charging circuit. One of the pins in a 7-pin receptacle provides this constant power but a 4-way doesn't (it only has brakes, turn signals and ground).

Next, check to see if the 12V charging circuit is on any time the truck ignition is on but off any time the truck ignition is off. If the charging circuit is still on when the truck ignition is off, you'll just run your truck battery down unless, of course, you add an isolator to the circuit.

Finally, remember that you'll be charging your camper battery through a very long set of wires that run all the way from your truck battery to the rear and then forward again to your camper battery. There will be a voltage drop that will not let your camper battery be charged anywhere near all the way.

Here's my situation: 2011 F-250 with 5th-wheel package including a bed-mounted 7-pin receptacle. I tested with my voltmeter and confirmed that the 12V pin on the receptacle goes dead when the ignition is off - no isolator needed. I bought a 7-pin plug and connected up the power and ground for the camper. I also connected the camper running lights to the tail/running lights pin on the plug.

This works great for my needs but, honestly, I think my roof-mounted solar panel does a better job of charging the camper battery, even while driving. During daytime, of course.

It sounds like BBZ has a portable solar system that's not deployed while driving. So a connection to the truck's charging system is easy to try, assuming you have a 7-pin receptacle already. Even if it keeps the camper battery at 70%, that's something.

Good luck

 

[ntsqd]

I spent a bunch of time and money setting up to charge from the alternator, then I later added fixed solar to the roof. Had I it to do all over again I'd do the solar first and then assess how much, if any, charge I needed from the alternator.

With the new to us camper already having solar on it the decision was taken away from me and I've not yet needed to set up the alternator charging. I will do so, but I need to upgrade the wiring between the batteries and the load panel, and access to do that isn't easy.

I'd first put in a battery monitoring system of some sort. Both Trimetric and Victron seem to be popular here.
After you've had some experience with the monitor in place you can size the solar panel(s) appropriately.
Then you can decide on if you need an alternator connection.

Hint: If you suspect that the solar can do most of the job and you'll only need to "top off" with the alternator you might have a look at the Ctek Duo 250SA for your charge controller. The reason for mentioning this option is that it can handle two different charge inputs. One from the solar panel(s) and one from the alternator. This will naturally disconnect the batteries when the engine is off, and it will do a better job of charging your camper batteries than will the alternator's regulator.
https://www.ctek.com/products/on-board/d250sa

 

[esimmers]

Good points there by ntsqd, especially if you're willing to put some serious money into roof-mounted solar panels, battery monitoring and an isolator, CTEK or otherwise.

If you're just trying to get a bit of charging for minimal cost, your choices are limit to finding the easiest way to connect your truck charging system to your camper battery and installing an isolator (or remembering always to unplug the connection to the truck when not driving).

 

[ckent323]

I tried using the power from a 7-pin hitch connector to connect to the camper pigtail. My camper has an Iota DLS-30 power converter connected to an IOTA Distribution/Breaker panel. I had OEM 6V Golf Cart type house batteries connected to the power distribution panel which I have since upgraded to 6V Deep Cycle AGM batteries. I used a custom made pigtail with appropriate connectors on each end to connect the 7-pin socket to the camper plug.

I found that the small wires that come from the truck to the 7-pin socket did not allow adequate charging of the batteries although it did manage to send some power. For powering lights it is fine but it will be hard to keep up the batteries if you have a 12v refrigerator based on my experience.

I have since added 200 W of solar panels and a Victron charge controller along with a Victrron BVM-712 battery monitor setup which has kept the batteries fully charged. I also ran 6 ga wires from the truck through a Blue Sea Ml-ACR to the camper house battery bank. However, I have not needed the direct connection from the truck yet and the ML-ACR switch has been off since I installed it.

If I were doing the Solar knowing what I know now I would use a set of panels providing at least 300 W and use a Victron Blue Solar 100/30 or 100/50 controller and a Victron BVM-712 Smart battery monitor.

Craig

 

[Colorado Mark]

This what I am going to use for my new Grandby. I have a GM truck.

In the under hood fuse & relay center, there is a 40 amp fuse and if you remover the cover, terminal lug #1 is for the rear 7 pin charge wire. That 40 amp fuse is for terminal #1, trailer tow charge wire.

I added a new 10ga wire to the lug and ran it to the new connector in the bed of my truck for the new camper.

I don't tow a trailer that needs a battery charged. If I ever do, I just need to be aware that it could pull too many amps and pop the fuse.

Key off and terminal #1 turns off. Only activates with engine running.

 

[ntsqd]

A thought, mentioned here a lot on this topic, is what seems like it should be a large enough charge wire probably isn't. The reason is the length of the total charge circuit, have to include the ground path in the voltage drop calculation. I use this page and work for less than 3% Voltage Drop on charging circuits.
http://www.ancorproducts.com/en/resources/three-percent-voltage-drop

An insidious loss is trying to use the chassis as the ground path with high current. Every weld in the chassis has resistance. At low amperages this isn't usually too big of a deal. At high amperage it is a big deal and this is why the camper charge circuit from the alternator should include a ground wire/cable of the same size as the hot.

 

[smlobx]

Plugging a truck camper into your 7 pin connector is what most truck campers do.
I’m not familiar with fwc wiring but the rest of the industry uses this method and it will charge the house batteries very easily, usually in just a couple of hours of driving.

 

[esimmers]

ckent323 and others correctly point out that long wires and small diameter wires will severely reduce the amount of power sent from the alternator to the camper battery and certainly won't send enough to power a refrigerator running solely on 12V. Ask me how I know!

The original poster only uses the camper battery for LED lights and a small fan. If those are the only loads, it probably isn't cost effective to spend a bunch of money on solar panels, battery monitoring, etc. So powering off a 7-pin connector is an economical way to provide at least a fair amount of charging.

 

[BBZ]

Thanks for all the replies..

Now, how do I do it.. haha..

 

[Advmoto18]

Yes, one can charge a house battery with a 4 or 7 pin connection.

But, not really a good idea for a standard equipped vehicle.

If your truck came with a single alternator, without any additional options for a travel trailer or camper, then you will be asking a lot of your alternator if wanting to charge house batteries.

First, an alternator in single installations is designed to maintain the crank battery and power the vehicle's electrical bus or distribution panel. An alternator scales its output based on demand by the bus and condition of the crank battery. Further, an alternator produces constant voltage for charging, 13.5 - 14.5. Not 3 or 4 stage charging as with "smart" battery chargers. As such, internal temperature of the alternator can stay relatively high for an extended period of time while charging vehicle and house batteries and powering the bus/distribution panel. Heat is the enemy of the stator in the alternator. Operating at a high temp for an extended period of time will ultimately lead to early failure of the stators. While the alternator operates at a constant voltage, resistance in the electrical system determines the amperage output of the alternator and its operating temperature.

For this reason, many of the HD domestic trucks provide for a second, or dual, alternator setup. Such a setup reduces the load on both alternators allowing each to operate at lower internal temperatures.

In dedicated overland vehicles, upfitters will often install a second alternator wired to a dedicated distribution panel for the travel trailer/camper house batteries/electrical system.

For the purposes of the OP, with his small electrical demand in the camper, going through a 7 pin would be the easiest method.

 

[wildlife2019]

I use the factory 7 way rv power feed. I spliced in another line (with appropriate rated dpdt* switch) from the plug feed so that I can isolate it if I should need to charge the trailer from time to time instead of 35ah agm batt. that's in truck bed. I use it for the one LED dome light under cap that burns less than 1ah, and one fan-tastic endless breeze ~3ah, and one phone charge socket.

With such a small load I'm putting on this relatively inexpensive battery, I have had no problems getting 6+ years running like this. Trust me.

To repeat what others have stated. Isolating it from your vehicle battery could save you future worries of being stuck.

*using it as a spdt switch in actuality

 

[craig333]

Like advmoto said, you'll get a constant voltage (check it with a volt meter to be sure ) which is okay for a bulk charge but for adequate battery "life" you should put it on a good smart charger whenever you can.

 

[Machinebuilder]

Let me throw a flag on some of the info in the last couple posts.

On newer vehicles the alternator is not putting out a constant voltage. they have a battery management system built into the vehicle electronics that lower the voltage.

I used the trailer connector from my 2011 F150 to my Granby, and it was adequate charging for using the lights in the camper.

When I added an Engel fridge I found out about the vehicle BMS. I don't know if it would have ever recharged the house battery adequately.

That's when I added solar, which is great.........until I went camping for a cold rainy weekend.

I'm still working out a good reliable way to keep the hose battery charged with minimal driving and minimal solar, and be able to run the heater and fridge for more than 1 day.

 

[Vic Harder]

Even with the onboard BMS in newer trucks, when you add the house batteries into the equation, the BMS now "sees" the combined battery status and will adjust itself accordingly. To do that well, it needs to have the two batteries as "close" together as possible. Not talking just distance here, but distance and wire gauge = perceived distance (or voltage loss if you like).

Machinebuilder, I wonder if a CTEK 250 might work well for you?

 

[Machinebuilder]

Machinebuilder, I wonder if a CTEK 250 might work well for you?

I've considered it, I'm trying to get some things worked out and better monitoring installed. I'm kind of busy at work and the early darkness this time of year has really slowed my progress.

 

[Colorado Mark]

When I ordered my Grandby, I went with the bigger 160W panel. I really want to be able to rely on what I have but, for longer trips pick up a used Honda EU2000 generator on craig list to take along.

I really, really don't want to use a generator but. . . . .

Now you don't have to worry about cloudy days or starting the truck. I picked one up for $800. Looks & runs like brand new.

Of course you would also now have to carry a spare gas can. I have a 3.5 gal Rotopax. My truck burns gas. Dump the gas in the spare can in the truck when heading home.

 

[rando]

Mark,

Unless you are planning a lot of time in Alaska or the like, I doubt you will need or want the generator. I also have a 160W panel and in the Rockies and Southwest, solar and the alternator can easily keep up. If you do have issues with shading, you may do better to go with an additional portable solar panel. Lighter, easier and most importantly quieter than a generator.

Congratulations on the new camper, and welcome to the cult!

 

[Colorado Mark]

Thanks Rando,

A portable solar supplement sounds like a much better idea. Light as a feather and easy to store. And even though its a Honda, I really don't want to listen to a generator.

My wife & I really do not want to take the generator. That's the whole reason we wanted our Grandby set up like we ordered it.

If we wanted to stay in campgrounds or listen to generators, we would have bought a 40' triple slide-out ultimate behemoth with, the fake gas fireplace and marble floors.

YUCK!