12 volt Battery wiring

This is a typical 30A Wiring Configuration for the RV Trailers. This is bit larger than your 1994 Jayco Eagle 10-foot base POPUP but the concept is the same...


INVERTERs really eat up your battery power especially if you are thinking about firing up an electric coffee maker. I am quite certain your only chance to have this is to use a Camping type percolator that is heated up with your propane cook stove.

This is my layout for a my 2008 OFF-ROAD STARCRAFT 14 R/T showing where most of my appliances and electronics and batteries are located. To make it through just one day/night run off the batteries I need at least 255AHs of on-board battery capacity.

Just to give you an idea of what we had to do to be able to camp off the power grid for extended times...




Any leads coming from the tow vehicle should only be considered a DC trickle charge. The cables bring this 12VDC to your trailer is very small... Probably a maximun of 5-6AMPS DC current is all you will attain by doing this...

This is our love camping off the power grid places...


Our game plan is to do all the things we want to run inside our POPUP for the one day/night run off of the batteries then recharge the battery setup back up to their 90% charge state by connecting the POPUP TRAILER shore power cable directly to our 2KW Generator the next morning. This takes us three hours of generator run time during breakfast time using the POPUP trailer on-board SMART MODE converter unit. We use our electric coffee maker during the time the generator is running. Our GRIND and BREW Coffee maker only needs five minutes of 120VAC to make us fresh ground bean coffee then pours up into a thermos karafe...


To be somewhat successful you will have to plan for something very similar to this...

Of course it all depends on what you want to have running when off the power grid...

Roy Ken

I think either you're confused about the wiring, or perhaps something isn't quite making the trip from your brain to words to my brain without a breakdown.

A four pin trailer connector would not be used to charge the battery or power anything in the trailer other than the running/tail lights, the stop lights, and the turn signals. There is no constant power available on the connector--if the lights and brakes and turn signals are off, there is no power at all to any of the pins. The 7 way (and some but not all 6 way) trailer connectors do have a constant 12V power feed, but it would not provide sufficient power for any but a quite small inverter.

Usually the inverter would be connected to the trailer's battery with heavy cables, hopefully short ones, and the battery would also be connected to the breakaway switch for electric brakes, and of course to the other trailer house loads like interior lights etc. The lights and so forth often are controlled by a main shutoff switch of some sort. That said, the sky's the limit for how the wiring could have been mucked up by a previous owner of a used trailer.

Are you maybe looking at a common ground connection? Do you have 12V power in the trailer when connected to a tow vehicle and none when disconnected, or are you just trying to trace the wiring? Does the trailer have brakes, and if so what activates/powers them?

Here is how they did it on our 5er, as an example.



Don't forget the required breakaway set-up. Note that wire is not fused.

camper, had a 4 pin connector, and no battery, I'm adding this...
as the camper has a built in 12v to 110 converter, and is wired of the light circuit of the 4 pin connector, and I don't like that Idea.. I've found the answer to that is a 7 pin connector,
the adding a battery is so the coffee maker, and radio,etc can be used if the tow vehicle isn't hooked to camper, like on an ice run, beer run food run.. or just out..
and also keep the fridge powered, if need be..

"I'm trying to figure out the best way to wire in a battery to the
trailer.It has a 12v to 110v ac converter and it "looks" like that
gets fed from the tow vehicle"

I doubt that it's wired that way, All TT I've owned have the battery wiring already installed. Usually the battery at the front in the A frame. You should 2 heavy duty cables (ground and +ve); The +ve should go all the way back to the 120/12 converter/inverter.

"if anything to have 2 batteries hooked to tow vehicle ,one in it, and one on trailer."

Not sure why you want to do this - if you need to charge the TT batteries, there is a pin in the 7-pin connector which is used for this purpose.

"I'll also want to add a low voltage cut off";

Again, not sure why you want to do this; I have digital voltmeter attached to the dual batteries and just keep an eye on the voltage; I have a battery cut-off which disconnects the battery from everything. I have a solar wired in, so my batteries never go belo2 12.7V.