I have a travel trailer and would like to know if while moving the trailer's battery/s are being charged by the truck. Is this normal? And does my truck do this? And can I check to see if it is doing it.

And do you know if it is a fast charge or more like a trickle?

Thanks!!!
Chris

 

put a meter on the trailer battery and read the voltage. Start the truck and read the voltage again. If its higher the truck is charging the battery. No change, no charge. I have a 2000 and I had to install 1 or 2 relays to get it to charge on mine.

 

I have a 2002 F-350 and had the same problem with my trailer not getting charged. Take the access panel off from under the steering wheel, then remove the black plastic cover that covers the fuse panel. Look for the numbers on the panel and the fuse number is 115. It is labled " Trailer tow battery charge". If you don't have the cover or owners manual, the fuse you are looking for is a light blue square unit, not the normal blade type fuse. It is on the BOTTOM ROW, and counting from left to right, it is THE THIRD FUSE. It is square and powers the round socket you plug the trailer into. One word of warning...if you attempt to plug the trailer into the truck while the camper is still plugged into shore power---(110 volt outlet) it will blow that fuse because you are sending 12 volts through the battery charger TO the battery and also sending DC back out through the umbillical cord toward the truck. As it sends 12 volts back into the truck it will blow the fuse if you start the truck cause you are trying to send 12 volts the opposite direction. I am not sure which connection you can check on the round connection but it should have a diagram of what wire does what on it. Hope this might help a little. I went through the same thing last summer...Take care, Dave

 

There are two relays that should be installed as previously mentioned, one is for the aux/back up lights, the other for trailer tow charge. At most it is a small step above trickle. You can maintain the batteries and charge some, but if they are dead, it is going to take a while to get them fully charged.

 

My trailer circuit was not charging last summer (I have a 2000 truck), and it ended up being one of the big maxi-fuses under the hood that was blown on mine. If I remember, it was a 30 amp fuse.

 

What's happening here is that the combined power converter and trailer battery (nominal 13.6 volts when plugged into shore power) are sending current to the truck battery to help start it, and this current exceeds the rating of the fuse. This current is equal to the voltage difference between the truck and trailer batteries divided by the resistance of the battery charge wire.

When cranking, the truck battery drops to a low enough voltage to cause a high enough current to blow the fuse. My solution was to go to Ford dealer a get a 30 amp circuit breaker which is normally used in the power window circuit, and use it to replace the conventional trailer charge fuse. If I forget and start truck with my trailer still plugged into shore power, this breaker trips, and then resets so I still have trailer charge function.

 

The circuit breaker definately sounds like the route to go in this situation.

 

jtharvey- do you remeber which one it was under your hood? i havent looked under mine yet, is ther only one 30 amp under there?

im being lazy right now but i will look soon

 

I can't remember at all which one it was. I had to look at either the cover or in the book to tell me which one was even the trailer charge circuit. I'd have to check the owner's manual to be able to tell you for sure.

 

The 30 amp trailer charge fuse is #16, looking in from the drivers side, it's the 4th one to the right in the first row, which starts on the bottom left.

I suggest replacing the conventional trailer charge fuse with a 30 amp circuit breaker which is normally used in the power window circuit. Look at the one in position #25 which is the 5th one on the right in the center row. They have a silver colored metal case!

 

well heres what i have found, i have no fusebox under the hood, just three little black boxes in place where the fusebox shuld be, i checked inside the cab and i have the #115 fuse in place but it seems it may have come out a little cause i pushed on it and it went in about 1/16-1/8", i took my volt meter and checked the volts at the 7 pin plug at the back of the vehicle and at first i was getting 5v, but i think i had a bad ground cause after messing around i got a 14.5v reading. so it seems i dont need the relays or whatever under the hood, i dontknow why i dont have the fusebox under the hood, my truck being a 2002, they maybe changed a few things around.

anyways thanks for your guys help, and in another month i will be able to make sure i infact will have my camper charging now.

the charging pin on the 7 pin connector it the pin that is located at 1 o'clock if you want to check the volts coming from it, just make sure you have the truck running while you are checking the volts