Battery protection

[Eagle6.7L]

If I connect my 5th wheel harness to the truck bed connector,and park for the night with no hook ups.Does the truck protect itself from the RV and allow it not to run down the trucks batteries.Or is the order the RV runs down it's batteries and then the trucks batteries,with no protection.I have hear both no it won't,and some say just unplug the 5th wheel at night because it will...

 

[kthaxton]

It will not run down your truck battery, it is on a relay/solenoid that disengages when the key is not in "run".

 

[Mingoglia]

It will not run down your truck battery, it is on a relay/solenoid that disengages when the key is not in "run".

That's good to know. When I had a '99 Ford years ago it would drain the truck battery if I didn't unplug it. At the same time though if I was disconnected and I ran my batteries down in the trailer to the point where I didn't have enough juice to start the genset I'd just hook the trailer to the truck (not turning the truck on, or putting the key in) and let it stay connected for a few mins to get just enough juice to get the genset started.

 

[kthaxton]

That's good to know. When I had a '99 Ford years ago it would drain the truck battery if I didn't unplug it. At the same time though if I was disconnected and I ran my batteries down in the trailer to the point where I didn't have enough juice to start the genset I'd just hook the trailer to the truck (not turning the truck on, or putting the key in) and let it stay connected for a few mins to get just enough juice to get the genset started.

That was a risky move (letting your truck battery charge your trailer batteries without the truck running)!

Your Ford didn't come from the factory wired like that did it?

 

[Tuesdak]

Get a voltmeter out and be sure. Point of fact you never know if someone changed this plug and ran it direct to the truck battery with a 30A auto reset breaker.

Turn the truck off, doors closed, and all the lights off. Ground one side of the voltmeter to the truck. Unplug the 5er and probe the connector on the truck - specifically the upper right blade for 12v -see pic from etrailer.com. if you have 12v on the 12v power you are supplying 12v to the 5er and will drain the truck batteries with the RV. Wait 15 min with the truck off and doors closed and probe again as power protection may shut it down like the dome lights after x number of time. Note you can probe all the connectors, but, the brake controller can show up as having 12v for the brake controller to see if anything is connected.

 

[endoscott]

My 2014 ram 3500, factory outlets for RV, did run down truck batteries after I left AF 24-5n fifth wheel plugged in far a week. Now I always unplug.

 

[GAmes]

Maybe the newer Dodges have a relay but mine doesn't. All batteries will discharge at the same time. The trailer just puts one or two more batteries in parallel. I strongly suggest you do as JDoremire describes and check the 12 volt wire in the plug with the engine off.

 

[kthaxton]

Are you referring to your 97 or something newer?

My 2000 had the relay.....I had to bypass it when I plugged a 12 volt cooler into the trailer connection in order to have the cooler run with the key off.

 

[GAmes]

I'm talking about my '97. But for an overnight stop there isn't any problem even if they don't disconnect. I don't disconnect any of the trailers I pull when I stop for the night. One time I was hooked to an RV with a bad battery that discharged my batteries overnight, so I disconnected the RV battery. I seldom overnight in my own RV without hookups, but with four batteries total, running out of juice isn't an issue.

 

[Eagle6.7L]

Mine truck was a ordered truck with a factory installed 5th wheel prep kit puck/ 7 way bed connector.As for the the upper right blade wouldn't you will have running lights/clearence running lights with the key off,so in that sense that would be always hot.Kthaxton ,not sure about the relay solenoid you are talking about.Doesn't the truck IPMS (Intergrated Power management system) look at the trucks batteries and sensing they are charged,start releasing a charge to the 5th wheel batteries,and top them off as well.

 

[kthaxton]

It appears as though I was way off, my apologies, I was wrong. I just went and checked mine and sure enough, it has power with the engine off. I then looked through wiring diagrams for my 2000 (yeah, I kept the FSM, but sold the truck), the relay I assumed was for 12v charging, is actually for the trailer lights, it is simply labeled "Trailer Tow".
Going off of memory, I suppose the bypass I did many years ago was to connect the 12v trailer charging circuit to the second, deep cycle battery I installed and not as I said earlier. I also 'suppose' I've never left my truck plugged in over night.....at least not when I had much power draw.

I was wrong once before.

 

[Eagle6.7L]

Looking at a Bergman 7 blade plug outlet,assuming this is the vendor for RAM Truck division,I see on my Forest River website that someone posted a circuit similar to JDoremire post but that the upper right blade shows it to be "Battery Charging",this in my Owners manual shows that the upper right blade is just"Battery".
View attachment 95750

 

[GAmes]

If you remove the batteries from your trailer the battery terminal will allow you to use the 12 volt powered items in your trailer, whether the truck is running or key off. If a battery is installed in the trailer it will get charged while the engine is running. So, either label is accurate.

 

[kthaxton]

Yep, they are the same thing.

 

[Eagle6.7L]

I am not sure still weather the truck protect itself's from draining the trucks batteries,on a overnight were there is no hook-ups.GAmes I have a list from Forest River on what is available from the trailers batteries,everything except refridgerator which switch's to propane once shore power is disconnected.

 

[GAmes]

Nothing in the trailer prevents drawing down your truck batteries. As stated previously it only takes five minutes with a multi-meter or a simple 12 volt test light to determine if the battery terminal is hot with the key off. More than likely it is.

 

[Dieselnerd]

I have the 2014 factory wiring diagram in front of me as I write. The 12 volt terminal on the 7 way receptacle goes directly to the battery through a 30 amp fuse.

 

[Eagle6.7L]

Dieselnerd I to agree because,with the key off I still get trailer lights,so I know it is powered for sure,I just thought that the Intergrated Power management would prevent that draw,after the key was turn off.I say this because it you leave certain lights on it shuts them off automatically.Diesel Nerd can you post that portion of the diagram,thanks for the post up....

 

[Dieselnerd]

Here it is.

 

[Kirwin]

I think we maybe looking 2 separate things. Trailer running light power vice trailer battery supply power. Fuse 30 is rated at 30 Amps and connects directly to the 12 volt hot terminal in the 7 way plug. It is fed directly off the battery bus in main fuse box under the hood called a Power Distribution Center or PDC. This will drain the trucks battery via the trailer connector. The parking/running lights are fed through the trucks Power Distribution Center (PDC) fuses but is controlled by the Body Control Module(BCM). This is a complete separate circuit set up and will turn off when the truck lights go off after the preset time with the truck not running and the headlight switch on to conserve battery power. See the wiring schematic above.