12 volt

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janpaul

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Easton, Maryland
If you were to stop somewhere just to sleep while towing a 5er, do you need to unplug the trailer from the truck? The trailer battery will be running the heat blower and whatever else is on, although very minimal. If you do not unplug will it drain the truck battery? Does the truck system charge the rv battery going down the road?
 

N Smock

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Long Branch, NJ
Need to check the big center pin in the truck hitch before I can answer. If the center pin is hot with 12V then the answer is disconnect the truck since you could drain the truck battery, if not on 115 VAC. If the center pin is hot then the trailer house batteries are recharged during travel. Of course if the truck center pin is not hot then no need to disconnect and no the house batteries will not be charged during travel.


Nelson
 

janpaul

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Easton, Maryland
I checked that when I installed the plug in the bed wall and it is hot. If I remember correctly, I installed a fuse for that when I hooked up my trailer brake.
 

Lou Schneider

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It's not always the center pin that charges the battery.  On a Pollak7-way plug, pin 4 is labeled as 12 volts and the center pin is for an auxiliary circuit - usually the backup lights. 

http://www.marksrv.com/wiring.htm

I pull the plug when I overnight.  It's easier than waking up to find the both the house and truck batteries dead.

Whenever I start driving, whether it's after getting gas, an overnight stop, or whatever - I make it a habit to flick the truck's parking lights on and off.  Sometimes I'll do this while driving down the road, too.  The reason is I can see the trailer's front clearance light in my side mirror.  If I see it come on, I know the trailer cord is connected properly.  If it doesn't, I know I have to carefully pull over and double check the connector.
 

janpaul

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That's the way my pin config. is. I knew one was hot, just didn't remember which one. My memory is about as long as my hair ;D
 

Marsha/CA

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There is a "one-way pole" connector that can be added to the truck to prevent the truck battery from being discharged while you use the trailer battery.  We had a slide in camper on our truck.  As we drove the camper battery would be charged; but when we stopped and turned off the truck, we could still use the camper.  By using the one way pole, the alternator would charge the camper battery, but not draw from the truck battery.  The cost in '93 was $2.50 for the connector.  It's a simple add on.

Marsha~
 

Marsha/CA

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janpaul,

I'm not sure what it's called.  It's been a long time since we had it installed.  All I know is that it's a simple thing to put in.  It was installed in the truck on the line that went from the truck battery to the camper battery.  When we got it the man who installed our truck camper called it a "one-way pole", meaning it would charge; but not draw from the battery thus the name "one-way".  I can look on the truck and see if I can see a name or number of some sort; but it may have all faded after this many years.  I also pulled a gooseneck living quarter's horse trailer and didn't worry about that LQ's battery dying and then using up the truck battery either.

I'll look at the truck and see if I see any reference numbers etc.

Marsha~
 

2006F350

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Memphis TN
You didn't mention what your truck is, but most newer ones that are already wired for towing have a relay that will only supply power to the battery pin in the 7 pin connector when the ignition is on - at least Ford does from 2000 on.

Larry
 

Marsha/CA

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2006350,

My truck is a 1993Chevy dually Crew cab.  They might definitely have that one way thingie on the newer models with tow packages. 

Marsha~
 

kbfeip

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Dec 24, 2006
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Discovery Bay, CA
Anyone know if I have a "one-way-thingy", or where to look on my 2006 Dodge Ram?  I had the dealer install the tow package, which included the receiver and wiring.

How does one inspect or check to make sure?
 

janpaul

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Easton, Maryland
Mine is hot with the truck off. I took a test light from the +pin to -pin on the plug. The face of the plug may have the configuration on it, or look at the link in one of the earlier posts. I would imagine a diode would work as it conducts in one direction and is open the other direction.
 

Lou Schneider

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The problem with diodes is they introduce a voltage drop into the charging line.  They'll substantially reduce the charging rate of your trailer battery while you drive, unless you compensate by raising the charging voltage of your alternator.

It's simpler just to unplug the trailer when you stop for the night, then plug it back in when you leave.
 

Karl

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How does one inspect or check to make sure?

1. Shut off the engine and remove the key.
2. Make a test light by soldering a normal automobile stoplight bulb (or something similar) to a couple pieces of wire; one to each end of the filament.
3. Ground one of the wires to the frame.
4. Touch the other wire to each connector pin on the tow vehicle wiring plug. 

If the bulb lights when touching any pin, that pin is hot (12V), and that pin is not controlled by the ignition switch. HOWEVER, that doesn't necessarily mean the two batteries are connected together. While there is an "accepted standard" for tow/toad wiring, that doesn't mean everyone follows it.You still have to check the wiring yourself, or have a qualified person do it for you.
 

janpaul

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Easton, Maryland
Unplugging is pretty foolproof and the level of difficulty is right up my alley. ;D No more than I will do it, I'll just pull the plug.
 

wylecoyote

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Nov 21, 2006
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I thought he had a camper not a cotton picking trailer, I didnt know they even had lights.  ;D ;D
 
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