12-Volt RV Accessories

There are lots of 12-volt accessories for your RV.    Most come with a plug to fit in a standard 12-volt receptacle which is like a cigarette lighter socket.  You will probably want to add some sockets at convenient locations where you want to use your accessories.  When choosing a location, your primary criteria will be the convenience of using accessories, but there are installation requirements you need to consider too.  First, will there be a source of power available or can you safely run wiring from a nearby source?  Next, is there room to mount the socket?  You will need a flat surface with enough room in a cabinet behind it to accommodate the depth of the socket and wiring connections.  It should be located where it won't be in the way or damaged by contents in the cabinet.  In many cases the bottom shelf on RV cabinets is hollow. Y ou can usually pry up the paneling inside the cabinet and gain access to the space.  Take it easy and work your way along the whole edge so you don't make unwanted holes in edge of the panel.  Often there will already be 12-volt wiring inside for under-cabinet lights you can tap into.  There may also be room to mount the socket so it is inside the hollow space and doesn't intrude into usable cabinet space.   When I haven't been able to use the hollow bottom shelf, I usually mount the socket high in the cabinet and as far into a corner as possible to get it out of the way as much as I can.   12-volt sockets are  handy for using a "car charger" to recharge cell phones, I-pads, etc.

If you need a 12-volt socket outside, use a marine-grade waterproof socket.  You may have to go to a marina or boat supply store to find one.  I use such an external socket on my motorcycle trailer to plug in my strobe lights.  Before I installed the socket, I had to run the wiring through an open window to an inside socket, which was always a bit of a nuisance and not good at all in inclement weather.  Note:  these sockets are only water proof when the attached cap is closed so use in rain is not recommended.  The covers only keep the weather out when nothing is plugged in.   For that reason I have installed permanently mounted and wired strobe lights on the roof of my motorcycle trailer.

Many RVs come with general purpose area lighting under the cabinets.  You may want to add some high intensity reading lights.  You will probably need to cut a hole in the bottom of the cabinet to accommodate the new light fixtures.  Then wire the new lights to the wires that feed the existing area light.   Most reading lights will have a built-in switch.   If yours doesn't, you'll need to put a switch in the hot feed between the source and the light.  The best place to put it would be beside the new fixture, but you may want to mount it through the face or side of the cabinet instead if that would make it easier to use.  Just make sure the wires and connections are protected so they won't be jarred loose or shorted out by contents in the cabinet.  Mounting the switch adjacent to the fixture should allow all the wiring etc to be safely concealed inside the hollow shelf.

With a little research you can probably find 12-volt versions of most common household electrical appliances including radios, TVs, VCRs, corn poppers, hair dryers, mixers and blenders, just to name a few. 12-volt appliances can be used in RVs and you can run them off your cigarette lighter in your vehicle when tent camping.   If you plan to use 12-volt appliances, make sure you have sufficient battery capacity to handle the load and monitor your appliance usage and battery state.  It will be very disappointing if you turn on the blender and all it does is hum softly and perhaps even more disappointing if you wake up cold in the middle of the night because you ran the batteries down watching TV all afternoon and the furnace has stopped working and is only blowing cold air! And the ultimate nasty surprise:  you drained your batteries and can't get your vehicle started to go home!  Motorhomes usually have separate isolated battery banks for the engine and the coach, reducing your chances of running down your starting battery.   But if you're using the cigarette lighter in your car or tow vehicle to power 12 volt appliances while tent camping, you will need to closely monitor the level of battery charge to avoid getting stranded.

If you can't find a 12-volt version of a 120-volt appliance you want to use you might be able to use an inverter to supply 120-volt power using  your battery bank.   Inverters convert 12-volt DC from batteries into 120-volt AC power.  You can get small ones (100-400 watts) that  plug into 12-volt receptacles to power a single small device (like a laptop) or hard wired ones (up to 3000 watts) that can run several outlets.  About the only down side to inverters are there is some loss of energy in the conversion process and keep in mind that 120 volt appliances will use 10 times the energy of 12 volt appliances of the same amp rating.  Inverters are sometimes a good way to run your TV and entertainment system without running the generator -- if you have a enough battery capacity.

Most RVs come with one or more auxiliary power sockets (12-volt receptacles like cigarette lighter sockets). Why would you need more auxiliary power sockets?  Think about what you will be using them for.  Do you need a portable fan near your bed?   Do you need a convenient place to plug in your cell phone charger?  How about chargers for re-chargeable lanterns and entertainment devices?  Portable air pumps?  You can buy 12-volt TVs, DVD and VCR players for use in your RV and you'll need a place to plug them in.  You may want to install a weatherproof socket on the outside of your RV where you can plug in air compressors to pump up OHV tires, 12-volt work lights, even 12-volt fans to cool the "patio" under your awning.   If you add an exterior socket, be sure to use a waterproof, marine-grade fixture.

Wiring your accessories.  If you don't need accessories to be portable or don't need the ability to use multiple accessories in the same place you can hard wire them.   Lights are almost always hardwired. Permanently mounted fans should be hard wired too.  If you need a socket to plug in your cell phone charger or plug in a portable fan, install a cigarette lighter socket.  Regardless of what your are wiring, pay close attention to the polarity -- connect hot leads of the accessory or socket to the 12-volt power supply and the ground leads to a vehicle ground.  RV 12-volt wiring usually uses red wires for hot and black for ground, but test your wiring to be sure.  Owners (and even mechanics) often use whatever they have on hand when adding accessories so wiring could be any color.  Connect the ground clamp of a test light to a known ground and touch the probe to the wire to be tested, making sure to contact the metal conductor and not just the insulation.  The test light will come on when you touch a hot lead but will not light when you touch a ground wire or other non-powered wire. Connecting accessories backwards can damage some electronic components or create a potential shock or fire hazard. 12-volt DC electricity isn't as dangerous as 120-volt AC power.  You probably won't even get an unpleasant tingle but it may create a situation where arcing can occur and cause a fire if you cross-wire things.  For most 12-volt connections you can use wire nuts -- plastic cones that twist onto the ends of the two wires to be joined.  Strip about 1/2" of insulation from both wires, twist the wires together, then twist on the wire nut.  Twist the wires and the wire nut in a clockwise direction for installation.  Turn the wire nut until it is snug, but don't over-tighten or you'll risk twisting off the wires.   For even more permanent and secure connections you can solder the wires together and wrap the connection with electrical tape or use heat-shrink insulation.

Whenever you add accessories you want the installation to look good.   If you're adding a cigarette lighter socket, make sure you drill the right size hole so it fits snugly.  Automotive style receptacles are designed to install through a thin metal or plastic dash panel.  Installing them through thicker wall panels in RVs may require some modification.  Receptacles designed especially for RVs come mounted in a chrome or other metal finished plate about the size of a residential light switch plate that simplifies installation and gives a nice, professional appearance.   Since they are already mounted, it gives you more latitude in drilling the hole and they can be installed on thick walls.  Look for 12-volt wall outlets at your favorite RV supply store.  When adding surface mount lights on walls or ceilings make the opening in the surface beneath the fixture where you run the wires large enough to push the wire nuts back inside so the fixture will mount tightly if there isn't room in the base of the fixture.   For best appearance, align ceiling fixtures to be parallel to adjacent walls.  You can usually do this by eye-balling them, but to be certain, you might want to measure and mark alignment. When mounting items on the wall, you may be able to use a level -- assuming your RV itself is level at the time.  Or measure from adjacent walls, ceiling, windows, or cabinets.   If you have to run exposed wiring, you may be able to disguise it with plastic wire guides or tracks.  These are available in various colors at home centers and usually have a semi-circular cross-section that is open all along one edge so you can push the wires inside.  There is an adhesive strip attached to the flat back surface. Be sure to clean the area where it will be attached so the adhesive strip will stick.  Rubbing alcohol is usually a good way to quickly clean the area.  You run your wires first, cut the guide to fit the length of the exposed wires, remove the covering from the adhesive strip, carefully slide the guide over the wires, keeping the adhesive away from the surface until you are ready to press it into place. Slip the wires into the guide, then press it tightly against the surface so the adhesive strip will hold it in place.  Usually keeping pressure on for about 30 seconds is enough to make it stick.  Use rubber grommets to protect wires wherever they pass through metal surfaces, rough wood openings, or where you want to make a professional looking penetration that will normally be visible.

Warning indicators.   Single 12-volt LEDs are easy to install as indicators to remind you when things are turned on.  One innovative RV owner wired one to the on/off switch of the water heater and installed it right next to the switch so he could tell when the hot water heater was turned on.  Most RV water heaters have a red light that lets you know when the water heater isn't working but should be (that is, it is turned on).  Most hydraulic or electric leveling jacks have indicators to let you know when they are in the extended position.  Another common place to add an indicator is on the electric step to let you know when it is extended and remind you to retract it before driving off (most motorhomes have an interlock to prevent this, but it is a nice addition to travel trailers).  The water pump usually has a lighted indicator, but if it doesn't this is another good place to add one.   you have an auxiliary electric heating element on your water heater you might add a 120-volt LED to let you know when it is powered.   If you can't remember if your TV antenna is up or down, try adding an indicator light to that too.   I have several outside lights on my RV and trailer and have added LED indicators inside so I can tell if the lights are on or off, even in the daylight.  You can also use illuminated switches that glow when in the "on" position.  Since battery power is a limited and quite precious resource when camping, being able to detect and eliminate unnecessary light usage can significantly reduce battery drain.

Plug it in!