How to Upgrade RV Power with USB Charging Ports

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When living life on the road, reliable access to power is essential. Whether you’re boondocking off-grid or camping at a well-equipped RV park, having versatile power options makes a world of difference. In this guide, I’ll walk you through how to install 12v USB charging ports in your RV, a practical upgrade that ensures your devices stay charged without relying solely on 110/120v shore power.

Drawing from my experience of over six years as a full-time RV dweller and four RVs later, I’ll share the step-by-step process to enhance your RV power setup and make life on the road even more convenient. This is my fourth travel trailer since getting on the road; I started with a 21-foot 1996 Thor, moved to a 23-foot 1997 Coachmen, then to a 27-foot 2000 Skyline, and finally to a 32-foot 2016 Heartland.

I performed this upgrade on every one of the first three rigs and had the presence of mind to document the process fully on the first. So, I’ll share that process here, rounding it out with some smart ideas I learned since then. The only difference from that first installation is that when I do it this time, I’ll install a hybrid of USB-A and USB-C outlets because the devices I’ll use with them use both cables.

Let’s start with understanding 12v power, as opposed to 110 (or 120) volts, which is what you generally find in a sticks-n-bricks dwelling.

Understanding RV Power Systems

12v power is DC or a direct current system. You may be familiar with this in your car or truck. The cigarette lighter outlet (more properly referred to as a “bayonet” port) is a 12v DC outlet. You probably use yours most with a phone charger or a dedicated GPS navigation system. 110/120v AC is the type of high-voltage power you find in a stationary dwelling.

Here are their differences, in a nutshell:

• Power: AC systems typically operate at higher voltages and frequencies, whereas DC systems maintain a steady voltage level. If AC is considered 120 volts, it operates at ten times the power of 12 volts.
• Transmission: AC power can be transmitted across long distances without much energy loss, unlike DC. You want to eliminate long wiring runs with 12v because it’s low power, and every foot of wire it must traverse causes friction that effectively steals some of its power.
• Applications: AC power is used to operate a wide range of appliances in homes and offices. DC power is widely used in low-voltage applications, such as charging digital devices, batteries, automotive accessories, and aircraft applications.
• Conversion – AC is easier to convert and more efficient in stepping up or down functionality in voltages.

Recreational vehicles contain both 110/120v AC and 12v DC systems. The beauty of the 12v portion of the system is that it can and does operate free of outside electrical hookups or “shore power.” The pain is that you must find a way to keep your house battery(ies) charged up because they power your 12v system.

This is an important concept if you do a lot of boondocking because you need devices and accessories that can work without 110/120v outlets.

Your 12v system charges via your tow vehicle’s alternator through the 7-pin plug that also operates your RV’s brakes and external safety lighting (in a trailer); or via an internal connection (in a motorhome) while you’re driving.

This is great free power from something you’re already doing anyway. Still, that charge only lasts a few hours, especially if you use lots of interior lighting, charge your devices, or operate 12v accessories such as fans or radios. Plus, you’ll not always be driving every day, so without shore power, you’ll need to depend on your house battery.

The two most popular methods to charge house batteries are the use of a gas or diesel-powered generator (internal in larger RVs or external in smaller ones) or a solar panel power system.

I’ve always had smaller trailers, so I carry a gas-powered external generator just in case, while my main charging source is a robust solar power system. Properly wired and connected, both of these methods can charge both 12v and 110v systems.

Locating the 12v Fuse Panel

This article will deal mainly with a set of two matching 12v USB-A charging ports I installed on an otherwise fairly useless ledge I came to think of as the Foredeck of my first small trailer. It began as the back of the dinette but was basically just empty, wasted space. I quickly turned the ends into a book library on one side and an insulated cooling area on the other while the center console housed the new 12v ports.

I first had to figure out where to attach the wires to tap into the trailer’s existing 12v wiring system. That would obviously be through the fuse box, so I located that amidship near the floor and beneath the microwave oven in my galley kitchen cabinets.

As with most RVs, the 12v fuse box was co-located with the 110v circuit breaker box and sat atop the onboard electrical converter, which turns the power generated by the tow vehicle’s alternator into usable forms inside the RV cabin. I just had to release and drop the top half of the steel access panel cover to reveal the fuse and circuit breaker panels.

To use either type of power, you must access the back of the fuse box, to lead each wire to the proper circuit breaker or fuse for each circuit. In this case, you’ll use a 12v fuse connection for the positive wire and what’s called a “bus” — a metal bar screwed, in this case, into the floor of my trailer beneath the kitchen cabinets.

This serves to ground all circuits to the steel frame of the trailer, which ensures—as it does in a house—that I won’t be electrocuted when I use any of my electric appliances. The negative or ground wire (usually black, but that’s your call) attaches to that bus bar with a set screw.

I matched the 18 ga. wire provided with the ports when I needed more than they came with. I used spade-type crimp-on connectors to attach to the fuse back. Always give those a pretty good yank to ensure they’re solidly connected before moving on to the next task.

Fusebox Access

In this installation, the fuse box’s previous hookups used fairly short wires, limiting how far I could pull the panel back out to see and reach it to attach the new wires (see photo).

I knew it would be very easy to get confused about which wire was which, which can be extremely dangerous when working with electricity. So even though I was working with the battery disconnected and no shore power, you can bet I worked very slowly, methodically, and triple-checked every connection before I made them.

I knew it would be very easy to get confused about which wire was which, which can be extremely dangerous when working with electricity. So even though I was working with the battery disconnected and no shore power, you can bet I worked very slowly, methodically, and triple-checked every connection before I made them.

I was also pretty focused on labeling the lines with my label maker. It has probably saved me, more than once, from accidentally killing—or at least maiming—myself.

I love my label maker and use it to keep me safe whenever I work on any RV electrical system.

When I sold them later, the buyer always appreciated my thoroughness, and I think it gave them confidence that I’ve kept up with the maintenance pretty well.

Under-Sink Wiring

That silvery tube in the previous photo is the onboard furnace ductwork. The furnace ignites, and its blower runs on the 12v battery system, meaning it will work whether I have external electrical hookups or not.

To give you an idea of the tight quarters I was working in, this photo shows how the wiring for both 110v and 12v had to run beneath the kitchen sink, inside the cabinets, and finally out beneath the port-side dinette bench.

This all served as a chase to keep the wires together and relatively protected from damage while also keeping them out of sight for good looks. It was very useful, but not easy to work inside!

Running Wires and Installing New Ports

The port-side dinette bench carries all the foredeck wiring underneath. This area also opens to the outside via the cargo hatch seen here because it’s a storage compartment.

This meant I had to keep all wiring running along the top so it wouldn’t get accidentally torn out when pulling items out or when stored stuff moves during travel.

You can see in the photo here that there are no existing 12v wires I could have tapped into to save myself from having to run another long length of wire back to the fuse box.

You can only see green wire (which I used to match the existing negative or ground wires to avoid confusion for myself and future owners) here because I had not yet run the positive power wires back yet.

I always hook up negative wires first for any new circuit because that way, I’m less likely to get shocked if a circuit happens to close accidentally. But be aware that a shock from 12v sources isn’t hazardous, just a little painful.

It’s not like taking a shock from a car battery while jumping it or from a dangerous 110/120v source.

Positioning the New Ports

I chose a hybrid double-USB/bayonet model for these ports because I wanted to be able to run the bayonet plug of my tire inflator through the window at that end of the trailer and charge phones and tablets.

I pre-drilled the individual holes for the 12v charging ports. One of each was attached to a two-hole cover plate, which I used as a template to position the holes (see photo).

The positive wire running from each circuit included an inline fuse. That is, they SHOULD consist of such. Some of those delivered in my orders already had them.

As you see in the photo below, I had to splice the fuse holders into others. This ensures that if one outlet goes bad, it doesn’t drag the whole system down, and there is good protection against fire.

The photo below shows how the double 12v outlet is wired. You can’t see it once it’s installed because the wires are underneath the foredeck top shelf panel.

There are four circuits (or, if you’re picky, two pos/neg circuit pairs) wired to each 12v outlet grouping I installed. This was a nice configuration because I could swap out the positions of each if desired, which was in one case.

The cover plate or escutcheon I used as a template to locate the drilled holes for each outlet also acts as a backstop, which will be placed first. It will locate the outlets and keep them in place while looking pretty nice.

Then each outlet was dropped into the top, and a thin nut was screwed around the port body back to snug it in place.

I was glad I had screwed, not nailed, the console cover in place because after the first few weeks of travel, some of these nuts had worked loose, and I had to go back in to tighten them.

After installing the second set of 12v outlets, I was ready to try them out!

I was so insanely glad to be able to plug in a 12v fan to move some air around in the hotbox my trailer had become in the early summer swelter! It was a well-deserved treat for a job well done!

Tools and Parts You’ll Need:

• A Phillips and standard screwdriver on the small to medium size
• Wire cutters/strippers / crimpers, preferably with appropriate-sized gauge holes
• Needle nose pliers
• Hole saw and/or jigsaw/plunge saw
• Flashlight or headlamp, depending on the space you’re working with
• Electrical tape and/or heat-shrink tubing
• 18 ga. insulated copper stranded wire (I used green and red, but you can use whatever colors make sense for you)
• Hybrid USB-A/USB-C ports

In Conclusion

Upgrading your RV’s power system with 12v USB charging ports is a simple yet effective way to improve your on-the-road experience. By following these steps, you ensure that your devices are always charged and ready, whether you’re enjoying a remote boondocking adventure or settling into an RV park. The convenience of having reliable charging stations within your RV not only enhances daily living but also adds a valuable touch for future resale.

With a bit of planning, the right tools, and attention to safety, you can transform underutilized spaces in your RV into functional power hubs. Now it’s your turn—start your own installation project and see the difference first hand. For more RV power tips and upgrade ideas, explore additional resources here at RV Inspiration.