Installing A USB Socket

Story and Photos By John Adey

Make it easier to charge your mobile devices on board by installing a USB outlet.

Photo of a USB socket with phone plugged inKeeping cell phones, tablets, and other portable electronics topped up is easy with a USB charging socket installed.

In this day and age, everyone has a mobile device of some sort. But keeping those devices charged up while on the water can be something of a trial. Many boats have a cigarette lighter or a 12-volt plug where it's possible to plug in an adapter. But the electrical contact is often far from ideal, and I'm not the only boater who's plugged in a phone to charge only to find it flat at the end of the day. A better option is a dedicated, dual-USB socket.

These sockets are a common sight in cars these days, and with the rising use of tablets for navigation and the evolution of decent waterproof/water-resistant cases for phones, USB-charged accessories are now commonplace aboard boats of all sizes. One advantage of the dedicated USB charger is that it's always there, never forgotten, never borrowed. And the USB charger socket, without an adapter protruding beyond the face, presents a very low profile.

Installing a charger isn't complicated; you should be able to complete it within two or three hours. To avoid repeated trips to the marine store, think the project through, then go and buy the necessary bits. Right is the list of parts I used to install one on my boat; these parts will work for most similar installations. Pay particular attention to the length of the wire you need. Measure the run of the wire carefully so that you buy enough. It's better to buy a couple of feet too much rather than a few inches too little.

You don't need a lot of specialty tools; you're likely to have most of what you need in the toolbox already. However, investing in a set of ratcheting crimpers will make this, and future jobs, more enjoyable.

The first thing to do is to turn off or, better yet, disconnect the battery. If you have AC circuits on the boat, disconnect these also. To protect you and the boat, there should be nothing live. Don't reconnect the power until you've finished the project. Next, (see photo 1) drill the hole for the socket. I used a spade bit, but a hole saw would be better because it cuts a cleaner hole and creates less dust. The drill bit should be just a little larger than the threaded portion of the USB socket. My bit was a little small, so I had to open out the hole with a rotary tool in my electric drill. Incidentally, this part of the job is a little dusty, so wear goggles, a dust mask, and gloves.

Clean up any dust and debris, then run the wire. Allow about 12 inches at the plug end, and tape this to the outside of the hole so it won't be lost as you run the remainder of the wire back to the breaker or fuse panel. Use a wire clip (see photo 2) to support the wire at least every 18 inches from the drilled hole to the circuit-breaker panel. It's OK to use a nylon wire tie to attach the wire to an existing bundle, but aim for a neat and tidy appearance, and make sure that the wire doesn't hang down, where it might get inadvertently snagged. On no account should the wire be attached to throttle lines, gearshift cables, or fuel lines.

When the wire is run, begin the connections. Starting with the source of power, you'll need a positive connection on the switched side of the main breaker, a negative connection to the negative bus bar behind the panel, and overcurrent protection in the form of a fuse (see photo 3). For both the positive and negative connections, use crimp-on ring terminals and heat-shrink tubing. It's extremely important that the ring terminals be the right size for the stud or screw. I hooked up the yellow DC negative via a ring terminal to an open No. 8 screw on the DC negative bus. I connected the red positive to one side of the ATC fuse holder, then hooked up the fuse holder to the switched side of the main-panel board breaker, in this case a quarter-inch stud. I used a butt connector to join the short pigtail on the fuse holder to the wire that runs to the socket.

With the connections made, (see photo 4) I screwed the fuse holder to a wood panel adjacent to the breaker panel. I used a permanent marker to note the size of the fuse I installed so I'll choose the correct size if it ever needs replacing.

When the electrical hookup has been completed at the main panel, turn your attention to the socket. Make the connections to the back of the socket in the same way that you made the connections at the panel, after first trimming the wire to length if it's a little long. But instead of using ring terminals, (see photo 5) use female spade connectors. The back of the socket is marked, (see photo 6) so make sure that the red goes to the positive terminal and the yellow to the negative. Note, too, that you need to slip the threaded ring over the wire on the inside of the panel; this helps hold the socket in place before you make the final connections.

Slide the socket into its home, make sure it's straight and level, then drill a couple of pilot holes for the self-tapping screws that come with the plug.

After adding a bead of suitable mastic under the flanges, (see photo 7) pop the socket back into place and install the screws. Finally tighten up the ring nut on the back of the unit. Clean off any sealant that's squeezed out, then reconnect the power. Make sure all is well by plugging in a phone or other suitable device and determine that it's charging. 

John Adey is president of the American Boat & Yacht Council.

— Published: December 2015


Parts List

  • 1X Blue Sea Dual USB 2.0 Charger Socket P/N 1016 (Mastervolt also makes a comparable one)
  • 15 feet 16AWG Ancor dual-conductor stranded/tinned wire red/yellow
  • 2X quick-connect female spade terminals (to match the wire and connections on the back of the socket)
  • 1X Blue Sea ATC fuse holder, (1X 12-16AWG butt connector to connect to the 16AWG wire to the 12AWG provided on the fuse holder)
  • 1X 3 Amp ATC style fuse
  • Heat-shrink tubing and nylon wire ties to support the wire
  • 2X #8x3/4 pan head self-tapping screws for the socket faceplate

 

A Color-Coding Option

Yellow is an acceptable alternative color for the usually black DC negative wire. This is allowed by the American Boat & Yacht Council in order to eliminate confusion with the AC hot lead, which is also black. Cutting into a DC negative is really no big deal; cutting into an AC hot lead is a different story. If there's no AC system on the boat, go ahead and use red (+) and black (-).

 

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