Desert Snow

Hey guys...I wasn't certain where to post this, but this seemed like a logical place.

I'm wiring up the JKU to an M1101 trailer and in the process have determined I'm an idiot when it comes to 12v electrical setups.

I put together a schematic of what I think is the right approach, but really need someone smart and experienced to get their eyes on my plan. I'm attaching/uploading the schematic.

My questions are the following:

Based on the watts used what gauge wiring should i use for each circuit? And, what size in line fuse should I use?

Also, you'll see I'm looking to use 2 deep cycle AGM batteries and I'm not certain if running them in parallel is wise or not.

In general, am I on the right track based on my schematic?

Thanks in advance!

countrydude1992

For the batteries, wire them parallel (red to red, black to black) as long as they are both 12v and are both the same battery. If one is larger than the other, they will constantly be trying to send power to each other and its just a big hassle and reduced lifespan. If they are different batteries, install a battery isolator between them.

As far as the diagram goes, it all looks pretty good but since you have the fuse panel coming right off the battery, you do don't need more fuses after the switches. But better to have too many fuses than not enough.

I personally would have all of your lights and accessories wired to relays even though the amp draw is pretty low for each device. This way should you ever need to change it out, you don't have to worry about whether or not the switch can handle the amperage of the new device.

And for wire gauge, I'll attach a chart that I love to reference.

countrydude1992

Oh and be sure to add a volt meter to the panel or directly to the battery. This way you can easily see what voltage your batteries are running at so you know when they need to be recharged.

*edit*
Just saw one on your diagram so nevermind!

14Sport

I would go with a 20A fuse for the inline fuse. And place it as close to the battery as possible. Any wire between the battery and fuse is unprotected and can cause a fire so you want to make it as short and secure/protected as possible.

Desert Snow

Thank you! Ok, a few questions:

When running in parallel how do the batteries drain? How should I wire in the 100w solar charger in this configuration--will both batteries split the charge when wired up to just one?

When referencing the chart you provided (awesome btw) and determining the length of my wire runs do I calculate the length based on battery to the energized device and then back to battery or just one way?

Totally grateful. Thank you so far.

Desert Snow

Ok, am in understanding you correctly: you're saying replace the 55A fuse I display between the battery and the fuse panel with a 20A? Also, there will be less than 18" of wiring between the batteries and the fuse panel.

Andy_PHA

I would suggest using at least a 10 awg wire from the battery terminals. Certainly if you are using that large of a fuse. Remember the fuse is there to protect the wire in the event of a short so a 50 amp fuse does not mix with 18 awg wire. Even if you drop down to a 20 amp fuse as was suggested you would still need to bump up to a 12 awg wire minimum even if the distance is short.

Desert Snow

Thanks for the response. The diagram shows an 8AWG wire not 18. The 18" depicted in the diagram represents the length of the wire from battery terminal to fuse box.

Andy_PHA

My bad misread the diagram.

countrydude1992

When in parallel, it basically turns them into one really big battery. they will both drain at an equal rate.

For the solar panel, be sure to get a solar charge controller. Solar panels typically will output a higher voltage than is safe to pump into 12v batteries so this prevents any damage and prolongs battery life.

For the wire runs, just calculate from the battery to the device.

And as others have mentioned, be sure than your main fuse coming right off the battery is rated to handle the load you have coming from your fuse panel (and not much more), and that your wire gauge is bigger than necessary. I personally like to go at least 1 step up just to be safe, and 2 steps up if there is a possibility of adding more devices in the future. Always have to plan ahead!