12 volt USB Charging Port

by Greg Zimmerman
Published: Updated:

Having a 12 volt USB port gives us more charging options.  We can charge devices on battery (no hookups or AC power).   The lone 12v outlet for the TV wasn’t enough so I added a dual USB charging port.

To access the area I mounted it, the furnace grate was removed by drilling the 2 rivets out.  The charger is a Seadog marine version for boats.  With dual 2.1amp ports it can charge tablets and phones.  It needs a 1 1/8″ hole to fit.  

For power I tapped into the furnace 12 volt wires.  The wires coming from the furnace are red positive and yellow negative. Casita splices them into different color wires. On ours the white is the negative and red is the positive.  For the splices, I used “posi-taps” which are more secure than the crimp on splices.   They’re also re-useable.


Lee December 27, 2018 - 11:08 am

Nice looking installation. Where did you get your wire taps. They sure look a lot better than that crap Casita uses.

Greg Zimmerman December 27, 2018 - 11:21 am

Amazon sells them in all kinds of assortments. I’m sure they’re too expensive for production lines, but they’re the best splices I’ve found. They screw on by hand and can be re-used. https://amzn.to/2CyZcMY

Dan Casey January 1, 2019 - 3:49 pm

Nice install ! What gage wire taps did you use ?

Greg Zimmerman January 1, 2019 - 4:23 pm

Yellow taps which are good for 10-12 gauge wire. I used 12 gauge wire which is a little overkill, but I like things heavy duty.

Kevin June 16, 2020 - 11:45 am

I tried hooking up Red positive and white negative coming off the furnace, using Posi ties, all I get is 6 volt….any suggestions.

Greg Zimmerman June 16, 2020 - 11:51 am

Email being sent!

Kyle Kuh June 24, 2023 - 5:32 am

Thanks for this! What are your thoughts on the approach you laid out here vs. wiring a 12V outlet into the existing DC panel? If you were to wire into the DC panel, were would you run the ground wire? Thanks!

Greg Zimmerman June 24, 2023 - 6:49 am

There’s enough DC wiring running all around the Casita that you can put a 12v outlet wherever you want. Just tap into one of the many lights that go in all the cabinets. No need to run new wires all the way to the power center.


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