Introduction: Install an Auxiliary Power Outlet in a Vehicle

About: I have worked in industry for 25+ years and have learned a lot from a lot of good people. I hope to pass a few things along and continue to learn new things!

With all the electronic devices we use today, there never seems to be enough Power Outlets in a vehicle, especially if the car is a few years old. If anyone rides in the back seat, they are usually at a loss for some power. You can purchase aftermarket sockets that plug into your power outlet, but many times these end up being bulky and you have a tangle of cords to deal with. I like to hard mount the power adapter in a central location, and I like to include a device with several USB charging ports. This Instructable will show how to mount and wire in a 2 socket power adapter with 2 USB charging ports in a 2007 Honda Fit. At the end are some pictures of outlets mounted in other vehicles.

Step 1: Gather Tools and Determine Location

The tools you will need are:

Screwdrivers, Wire strippers, Soldering iron, Drill and bits, Volt Meter or test light

Material required

Power Adapter (I like one made by Bestek sold on Amazon)

Solder, heat shrink tubing, electrical tape, connectors, small machine screws and nuts

The first thing I do is find a location to mount the Power Adapter. In this vehicle, there was a real nice spot along side the Parking Brake handle. It was centrally located in the car and easy access from the back seat. There were also several compartments molded in the housing near the parking brake that would be ideal to hold a cell phone or Ipod. I put it in place to eyeball it up to make sure there was still good access to the brake handle and it would not pose a safety hazard or pinch point. Once I determined that this was the location, the console needed to be removed.

Step 2: Remove Center Console

To remove the Center console, I had to take out a couple of Philips screws in the back. The front was held on by two plastic push pins that needed to be pulled out. Typically you can find a video somewhere on line that shows how to remove the console on almost any vehicle. I was very lucky in this case because the existing power port was mounted in the front of the console. It had a connector on the bottom of the port that could be disconnected and then the entire console could be removed from the vehicle and worked on outside of the car.

Step 3: Modify the Power Adapter

These power adapters do not have a provision for mounting and the only way I have seen it done was with double sided foam tape. I like to mechanically mount these devices. It is permanent and they stay in place.

Take out the screws holding the adapter together. Separate the two haves of the Adapter and drill two holes in the piece that receives the screws you just removed. I drilled 3/16 clearance holes for 8-32 screws. Once the holes are drilled, cut off the adapter on the supply end. Since I am hard wiring this in, I do not need the adapter.

Step 4: Mount the Adapter

Place the adapter piece you just drilled holes in on the location of the console where you want to mount it. This will be used as a template to mark the holes. Use the holes as a reference and drill two holes in the console to for the screws to go through. Once the holes are drilled put a nut on the backside and tighten the screw. Be careful not to over-tighten and crack the plastic housings. Once the housing half is in place, eyeball down it and determine where the wire will go through. Once you determine the location for the wire, drill a hole in the console that is large enough for the wire to go through. Once the wire is fed into the hole, reassemble the power adapter.

Step 5: Prepare the Adapter Wires

I stripped about two inches of insulation of the end of the power adapter cable. This particular cable has a braided shield on the outside which is hooked to negative and a red conductor inside this shield which is hooked to positive. I soldered some Male spade connectors on to these and tidied up the ends with heat shrink. The reason I used connectors was to enable someone to disconnect the wires if they ever had to remove the console again. On most applications I wire directly to the fuse box, but in this application it was much handier to wire to the existing power connector. These wires were not long enough to reach the power source, so I had to make up a couple of extension wires. On these wires I soldered the Female spade connectors. Once finished, I connected the extension wires to the Power Port cable. I slid a piece of clear Tygon tubing over the connectors to insulate them and keep them from vibrating apart.

Step 6: Prepare Vehicle Wiring

Check the connector that plugs into the existing power outlet with a meter. This will tell you a couple of things. First determine if the power turns on and off via the ignition switch. You should see around 12 volts with the power on and 0 volts with the power off. Also observe which wire is positive and which one is negative. In this case, negative is black and positive is yellow. After I verified the power was off, I cut off the existing connector about 2 inches from the connector. I stripped about 1/2 inches of insulation from the wires, slid on a piece of heat shrink tubing and wrapped my extension wire around the existing wire. I soldered 3 wires together. One was the source from the harness, one went to the existing power outlet and the other was the extension wire for the new power adapter. After they were soldered together, I sealed the connection with heat shrink tube and also taped it for additional security.

Step 7: Final Connections

Once all wires are soldered, plug the spade connectors together. Make sure that the wires are connected correctly. The positive is typically red and negative is typically black. In my case the positive from the harness was yellow and it went to red on the new power adapter. The negative was black and it went to the bare shield wire on the power adapter. I slid the Tygon tubing over my connectors to insulate and protect them. I also checked to make sure that no wires would be pinched or become entangled in any moving linkages. I secured the wire on the underside of the console with some good quality electrical tape to keep it routed correctly.

Step 8: Finished Product

The new power outlet is installed. There are now two new 12 volt outlets and 2 USB outlets. They are centrally located and convenient for any occupant of the car to get to. You also have the ability to use the original power outlet.

The most important thing to remember is always wire into a fused circuit. This will protect the wiring in the event of a short circuit and help prevent a fire. Be safe and enjoy the convenience of the additional power sources!

Step 9: Other Installations

Here are a couple of other installations I have done using similar techniques. The biggest difference with these is they are wired to the fuse box. The common feature is they are mounted near the center of the cars.

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