Expo Trailer Electrical System Question

Hey guys ive been on this forum for a while getting ideas for my M416 and finally "finished" (read: just began) it this fall in time to take the family on a few camping trips.


My plans this winter is to get the wiring done, and 12v systems are not my cup of tea. I could use some advice and for someone to check over my laughable diagram. Basically, I plan on putting a deep cycle battery (is that needed) in my tongue box. This will power my fuse box to power my lights/pump/usb and any future items I add. All accessories will be grounded back on the fuse boxes negative connections. The trailer battery will be charged by my Jeep while I am driving, and disconnected when at camp or stopped for long periods of time.


Here is where I am getting confused. I have a small inverter that I would like to hook up in case i have something i need to run that needs 120v. Where would this connect in my system? It has heavy leads, prob 6/8ga.

Secondly, I want to install a shore power plug for the times I take my family to the nice camp sites. Where would that connect to the system? Would I need a battery switch to eliminate the battery and only use shore power? Can I use the shore power to charge my battery while on site or when I am at home?

Any and all answers would help me a lot as I am getting turned around a lot trying to plan this system out. Im trying to keep it fairly basic but with the flexibility to expand in the future.


Thanks so much for the response. I have been piecing together my parts and have been hung up on those issues. Would you recommend using a simple battery switch in line with the charging wires coming from the Jeep? Can i use my shore charger for double duty to regulate the charge from shore power and my Jeeps battery power or is there no such thing.


typically i would suggest that you put the inverter on the truck and use it when running, since the inverter can drain the main battery pretty quick and does have some static draw on it as well (usually)..
For shore power i use a NoCo charger which has a plug on the trailer front box, i need to rig up a direct connection for 120v to the fridge but haven't yet. A modern fridge when cold will draw minimal amps running, if you could i would split the 120v and run a connection to the fridge they will default (depending on who makes it) to 120v when plugged in. But my Voltage needs are kept up with the charger while on shore power.

I try to keep everything 12v on the trailer and am now just using 1 G31 battery + 100w solar in my setup.


Pardon my ignorance (as I am working on a similar system) but if one were to ground the trailer battery to the trailer frame, is there any potential issue with the ground of the vehicle and ground of the trailer connecting through the hitch? Shouldn't these two be isolated?


If you want to integrate your shore hookup with your 12VDC system so that your battery charges while plugged in to 120VAC then I would recommend going with something like the Progressive Dynamics 4000 Series. This unit contains an intelligent charger for your 12VDC deep cycle battery, a fuse block for your 12VDC accessories and the ability to integrate 120VAC circuit breakers so you can have 120VAC plugs. This is a little more than most people typically do for an expo trailer but it definitely makes for a clean install.



I'll throw my 2 cents in. I have a jeep trailer set up. My thinking is don't mix the 2 my reasoning is if your trailer kills your jeep ( alternator, regulator or battery ) your stuck. It has always been my understanding that an alternator will never fully charge deep cell battery ( 70% at best ) so your charging system on jeep will always be charging as long as your plugged into trailer. I'm not fond of solar so I went generator. I grounded battery to trailer to save running ground wires to everything. I used genius battery charger and plug in on side of box for shore power or genset. image.jpgimage.jpgimage.jpg


Genius charger less than 100 bucks and tells your your battery state. Use a master switch between battery and fuse box and if you use inverter connect it straight on top of your battery. They can be tricky and if u plug into cig lighter that can be a lot of heat running threw jeep system. I'm sure there will be people disagree with me but I keep it simple and separate and I've had no probs also used master fuse right off battery. I also run my fridge straight to battery with inline fuse. 8 gauge wire


/dev/yj tow vehicle
How do you see install this in a typical Harbor Freight tongue box situation? I can't imagine that cover being weather proof, but perhaps you have another mounting option in mind?
Thanks for all the help guys. I think im going to make it easier on myself and do this system in phases. I plan on doing more off the grid camping than campsites, so I want to be able to charge my battery while driving and not require any shore power. This would mean that I would more than likely have to connect my inverter to the jeep. I can incorporate a shore charger in the near future. This would simplify my set up and installation.

Can anyone recommend a good "bang for the buck" deep cell?
I plan on using 10ga from my jeep battery to the trailer for the battery charger. What gauge would you use to run from the battery to my fuse panel?


I almost didn't click that link as those things are usually super expensive but you can get one for <$200, that seems too cheap so what is the catch?
No catch that I know of. There's a 4045 installed in my Oregon Trail'r Terradrop. They've been using them for years without any issues. In fact, I added a circuit to the 12VDC side for some additional USB charging ports in the cabin of my trailer. The 45 amp charge rating is pretty small but is more than enough to run everything in my trailer and continue to charge up the battery.