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Old 07-28-2015, 08:01 AM   #1
Join Date: Jun 2014
Posts: 56
Add 12v outlet question

I would like to add a 12v outlet outside to run a coleman powerchill cooler to keep my bottled water cool (I don't like using the 120v power supply for the cooler. It doesn't seem to work well and gets hot). I think the draw is only 4 amps (84 watts) when on DC.

By looking on this forum, I THINK I learned I could do it easily by tapping into the fuze panel and running the wire to the outside. I'm thinking I can do this by using a "littlefuze add a circuit" and tapping into the free 15amp fuze slot and grounding to the chassis.

So two questions for you:
1. Is this a sound plan? I don't really know if the converter wiring will allow that to work.
2. Will the 12v outlet work with the camper on battery only, or will the camper need to be plugged into the 30amp power to run it? I don't plan to run it dry camping. I just want to be able to test it when I'm done installing it. I don't have easy access to power in storage.


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Old 07-28-2015, 08:13 AM   #2
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Join Date: Jul 2014
Location: Sherman Illinois
Posts: 711
If you have a free fuse position just use the fuse to directly connect to your set up. Your arrangement should work directly off of the battery so no shore power will be required to test this arrangement. The converter will allow you to do this. I would use a 16 gauge wire as this can handle 20 amps slight overkill but a 18 gauge can only handle 10 amps. The most common problem with add on DC arrangements is that too small of wire is used for the application.

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Old 07-29-2015, 01:34 PM   #3
Join Date: Jun 2014
Posts: 56
Thanks. I realized the littlefuze add a circuit I had was a mini circuit, so it won't work. But I found the right size at Advance Auto yesterday. Interestingly, even though the wire is 16 gauge, the fuse tap is only rated to 10 amps. That's plenty, though, based on 4 amps for the cooler.

I bought two. I might add a 12v outlet in the trailer to recharge my phone if I'm dry camping.
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Old 07-31-2015, 06:33 PM   #4
Join Date: Jun 2014
Posts: 56
clr, or anyone,
I installed the outlet today. It was pretty easy overall. I ran the hot wire through the floor where there was already a wire bundle going down and I attached the weather-proof outlet under the trailer on the frame with self tapping screws. For ground, I used another self-tapping screw and ground it directly to the frame next to the outlet.

For power, I went to install the fuse tap, but when I took off the fusebox faceplate to run the wire, I found the connection screws (which I couldn't see before). So I didn't use the taps. If you look at the picture, you'll see the black wire I used on the screw 3rd from bottom. I used a 10amp fuse to make sure I don't load the wire too much.

I have a lot of experience doing 12v accessory installs in my truck, but since this has 120v and a converter involved, can you tell me if this is done correctly? I want to make sure I understand the wiring correctly, and that where I attached it will stay 12v once I hook up to shore power. I assume it will, since the wires are all fused with blade fuses...but electricity and I have a love-hate relationship.

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Old 08-09-2015, 03:06 PM   #5
Join Date: Apr 2012
Posts: 75
Looks good. It's all connected to the 12v side
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Old 08-09-2015, 04:07 PM   #6
Join Date: Jun 2014
Posts: 56
Thanks wicked.

I installed a couple of 12v sockets inside yesterday. I tapped them to the two posts under the black wire and fused them with 10 amps, too. My plan is to put in 2 x usb mini chargers for cell phones, kindles, etc. That's why I ran them with separate wiring.

Here's a pic of the final install. I put them there so I could easily replace the wood panel if I ever decide to remove the outlets. I just need to color the screws black to make them look a little better.
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Old 08-09-2015, 04:42 PM   #7
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Join Date: Jul 2013
Location: Akron, Ohio
Posts: 1,222
If doing electrical work it is important to get your components (wire & connectors) properly sized and your math correct.

84 Watts on 12 V is not 4 amp but is 7

16 ga wire is rated for more than 7 AMPs but this chart and calculator shows more than 1 volt drop if you are 10' run distance or more from the 12 v source.

Low voltage can cause overheating or poor performance for some appliances.

I trust you used properly sized connectors at every step and soldered and shrink tube any splices. Hardware store solderless crimp connectors are not designed to handle vibration. I have always used properly sized brass or copper solder ring or spade connectors with heat shrink tub to support the sire as the solder will make the wire stiff and the flex failure point occurs at the end of the solder. Shrink tube supports the wire and transitions the vibration.

Note I have done wiring on race cars that have survived the equivalent of 50,000 mile durability testing with no electrical failures using the above guidelines.

Write a blog on RV tire application 40 years experience as tire design engineer. Freelander 23QB on Chevy chassis is my RV. Giving seminars on RV Tire applications (not selling) in Elkhart May 17-19, Allegan MI June 6-9, & Gillette WY July 18-21 RV Tire Safety Blog
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