Hot outlet power switch from aux battery

[Milesar]

I've installed a loom to run from an aux battery straight to the fridge in the back. I thought it would be nice to have the ability to use the other 12V outlet with or without the car running, maybe through a simple switch to select between the existing wiring and the new wires to the aux battery.
I'm not much of an electrical genius and have poured through some other threads, can't seem to wrap my head around this one. I have seen Antmans 12V mod up front, but I was hoping to use the AUX battery for the always on.

Here is a diagram, sorry it looks like a 3yr old drew it. I'll add some photos when I put it all together, if it works out.

 

[eddiebx]

Before you start, please double check with a multimeter, but I am pretty sure the white wire is constant ground at the factory outlet and the green is the switched +12v.

Basically what you want to do is cut the green wire and connect the outlet end of the green wire to the common terminal of an SPDT switch; connect the harness end of the green wire to one of the switched poles; and tap into the +12v of the fridge wiring and connect it to the remaining switched pole. Since the factory outlet already has a constant ground, you won't need to tap the ground from the fridge wiring. I don't know what gauge wires you have running back from the aux battery and how your fuse situation is along the route, but it would not hurt to throw an inline fuse between the SPDT switch and the aux +12v connection--you don't want to burn up the factory outlet...

I recommend a 2 position
("ON-ON") SPDT switch for this because logically speaking you would probably only want to select one or the other, and not completely off? This link to the schematics of the switch I am talking about might help you visualize it better:

http://www.delcity.net/images/linedrawings/7700018.pdf

If you wanted to be able to completely switch the factory outlet off indefinitely, just find a 3 position SPDT switch and flip it to the middle. For example like this one:

http://www.delcity.net/images/linedrawings/7700028.pdf

Here is your diagram, converted from something that looks like a 3 yr old drew, to something that a 1 yr old drew

 

[Milesar]

Here is your diagram, converted from something that looks like a 3 yr old drew, to something that a 1 yr old drew

Awesome, thanks for the input. This looks like what I had imagined, a simple on/on switch to select one or the other. The diagram lines up with what I read earlier from the 12v mod upfront. I did test the lines and you are correct about the green/white lines.
I'm running 10 gauge wire with a 15amp inline fuse at the battery, it is the wiring loom from ARB for their fridge. My concern now is splicing the positive line from the aux battery, Is this ok with no protection between the two outlets? If the fridge is plugged in and I'm using a device plugged into the other outlet, if they could potentially damgage each other.
I'm not exactly fluent in electricity so I want to make sure I don't miss any gotchas before I send power down the line.
Thank for the help.

 

[harper7]

Awesome, thanks for the input. This looks like what I had imagined, a simple on/on switch to select one or the other. The diagram lines up with what I read earlier from the 12v mod upfront. I did test the lines and you are correct about the green/white lines.
I'm running 10 gauge wire with a 15amp inline fuse at the battery, it is the wiring loom from ARB for their fridge. My concern now is splicing the positive line from the aux battery, Is this ok with no protection between the two outlets? If the fridge is plugged in and I'm using a device plugged into the other outlet, if they could potentially damgage each other.
I'm not exactly fluent in electricity so I want to make sure I don't miss any gotchas before I send power down the line.
Thank for the help.

You would have to splice on the DC side of the inverter on the rear fender as it is AC at the outlet unless that's what your talking about already. Why don't you just wire a fuse box back there from the aux battery and you can run the fridge,inverter and any future lights ,ect. stuff back there.
Here's the blue sea 5025 one I bought for back there that will handle 100a per block and 30a per circuit and bought some 4 ga to run from the aux with a 100 amp fuse.It was like $40 on Amazon. http://www.amazon.com/Blue-Sea-Systems-Circuit-Ground/dp/B000THQ0CQ/ref=pd_sim_sbs_e_1
Where's Antman!?!?

 

[eddiebx]

Awesome, thanks for the input. This looks like what I had imagined, a simple on/on switch to select one or the other. The diagram lines up with what I read earlier from the 12v mod upfront. I did test the lines and you are correct about the green/white lines.
I'm running 10 gauge wire with a 15amp inline fuse at the battery, it is the wiring loom from ARB for their fridge. My concern now is splicing the positive line from the aux battery, Is this ok with no protection between the two outlets? If the fridge is plugged in and I'm using a device plugged into the other outlet, if they could potentially damgage each other.
I'm not exactly fluent in electricity so I want to make sure I don't miss any gotchas before I send power down the line.
Thank for the help.

I think the factory cigarette sockets are fused at 15A, so technically I guess you can just tap the +12V from the fridge harness straight to the SPDT switch and not risk burning anything without an additional inline fuse, and assuming you used thick enough wire (~16-18AWG). But let's put it this way, it will definitely not hurt anything if you threw in an inline fuse at the tap, and put in a slightly lower amp fuse.

As far as interference between the fridge and the cigarette socket mod, you should not experience any issues that can cause permanent damage. At best if you drew too much power at the socket and the fridge at the time time, the 15A fuse by the aux battery would blow.

Personally though I would go with Harper's suggestion and just get it over with all at once and run a fuse block setup back there; and then distribute the power as you please. This way you can neatly add to it in the future.

 

[Milesar]

I like the idea of a fuse box. This is my first dual battery setup so I am not too familiar with adding circuits and additional power, I was planning on figuring out the fuse box idea for other items in the vehicle at some point.
Eventually I hope to be able to move more items to the aux battery. There is enough room in the rear wheel compartment for a fuse box that would serve as a power source for items in the back. I am assuming they are fairly straight forward to install?
I know some fridges recommend a direct line from the battery to the fridge, I dont think throwing a couple items along the way would hurt. I just figured since I was back there the switch would be an easy addition.
I was just focusing on the 12V outlet since it would be the simple way to go, but if there is a way to hit the inverter and get AC as well, that would be bonus!

 

[eddiebx]

I like the idea of a fuse box. This is my first dual battery setup so I am not too familiar with adding circuits and additional power, I was planning on figuring out the fuse box idea for other items in the vehicle at some point.
Eventually I hope to be able to move more items to the aux battery. There is enough room in the rear wheel compartment for a fuse box that would serve as a power source for items in the back. I am assuming they are fairly straight forward to install?
I know some fridges recommend a direct line from the battery to the fridge, I dont think throwing a couple items along the way would hurt. I just figured since I was back there the switch would be an easy addition.
I was just focusing on the 12V outlet since it would be the simple way to go, but if there is a way to hit the inverter and get AC as well, that would be bonus!

If you plan to add a fuse box later on you might as well add it now instead of having to rewire everything down the road. It is in fact a very straight forward installation as you imagined; you basically just run one heavy gauge wire (fused at the battery) straight to the back and then distribute power from that point (through the auxiliary fuse box).

Electronically speaking, this would be no different to the fridge than connecting it straight at the battery (okay very minor differences, but nothing that would really matter ).

You can still do the cigarette lighter mod you originally planned to do with the fuse box installed; it just makes things even neater.

Lastly, the AC inverter mod might be a bit more involved than it is worth (there's a bunch of extra wiring with the switching between the 100w and 400w modes, etc.); I took a peek at the wiring diagrams and you might not be able to swap it over to the aux battery and back as easily as the cigarette lighter.

I was actually thinking about these same mods for myself, but I think I am going to skip the AC inverter and probably just get another aftermarket ACinverter hooked straight to the aux battery.

 

[Antman]

Here's an easy way to mount a fusebox along with some tips on installing it.
You can mount it wherever you like- doesn't have to be under the hood like in my install- BUT- it must be fused, and the fuse should be close to the battery.

Link:

Auxiliary Fuse Box Install