Last Updated on May 7, 2022 by Jessica Lauren Vine
One of the most useful, and most frequently overlooked tools for RVs is the portable 12V air compressor. Like any great RV tool, portable air compressors have several uses around the RV.
First, they are ideal for maintaining proper tire pressure on your RV or tow vehicle. This is important for safe travel, improved fuel mileage, and decreased tire wear.
Portable air compressors are also great for inflating the things you take with you on trips like toys, balls, pool floats, bicycle tires, golf cart tires, and ATV/UTV tires. They can also be indispensable for air mattresses and inflatable boats, kayaks, and paddleboards.
Finally, a portable air compressor can be critical for keeping you on the road when tire problems like leaks and flats arise. Here we’ll take a look at what a portable 12V air compressor is, how to use one, what to look for when buying one and why every RVer should have one.
What is a Portable 12 V Air compressor?
A portable 12V air compressor is a small air compressor that can run on 12 Volt DC power. While it may look like a typical tire inflator, there are some very important differences that make them much better choices for RV use.
Portable air compressors move air by compressing it with a reciprocating piston, just like the larger air compressor you may have in your garage. Unlike your garage air compressor, most portable units do not have a storage tank, although there are some units that do.
The advantages of piston-driven compressors are threefold.
- First, they can move air much faster than a non-piston-driven tire inflator.
- Second, piston-driven units are capable of reaching much higher pressures. RVs and tow vehicles generally have larger tires that are inflated to higher pressures than your typical passenger vehicle. This makes portable compressors the superior choice over tire inflators for RV use.
- The last advantage is durability. Piston-driven compressors tend to be built with an exceptionally sturdy construction which will provide years of service even with frequent use.
What Should I look for in a Portable 12V Air Compressor?
There are several things to look for when considering the best portable 12V air compressor for your needs. Let’s take a quick look at those items.
- RV-specific units. Some manufacturers have caught on to the usefulness of these compressors to the RV community and have begun selling “RV Specific” units. In most cases, it’s a standard model with “RV-specific accessories.” This may or may not be the way to go for you, depending on your needs. Look at the whole package and see if it includes things you don’t need or like. For example, Viair sells several “RV specific models.” My RV is a long travel trailer attached to a full-size SUV. The RV-specific units include things like dually inflators which I don’t need. Some models also have coil hoses, which I don’t like. I opted for a standard model instead with regular hoses and the extension hose I need to reach my trailer tires. This is better suited to my needs, saved me a little money, and works just as well.
- Size. When choosing a portable air compressor, it’s important to emphasize the “portable” while maintaining the performance you need for your situation. Smaller units will not include integrated storage tanks. Storage tanks are only necessary if you plan to inflate things away from a 12V power source. If you don’t see that as a necessity (which it usually isn’t), opt for a smaller tankless unit.
- Weight. Weight goes with size. Larger units will be heavier. Heavy things and RVs generally don’t mix, and having to lug a heavy compressor around a campsite or on the side of the road won’t be an enjoyable experience. Try and find the lightest unit you can that will meet your needs. With that in mind, don’t skimp on quality for lighter weight. A unit with more metal will be more durable but weigh slightly more than one with more plastic. The extra weight on the metal unit will pay off with a longer service life.
- Max Inflation Pressure. Look at the items you plan to inflate and choose a compressor capable of exceeding those pressures by a fair margin. The inflation rate will decrease rapidly as you get closer the maximum inflation pressure. Choosing a unit capable of inflating 20 or more PSI over your greatest need will ensure your compressor will never be too stressed during operation while still efficiently inflating your tires.
- Inflation rate. Inflations rates are given in CFM or Cubic Feet Per Minute of airflow. The CFM will drop as the pressure increases in the item you are inflating. This is why CFM for a given compressor is often given as a table showing CFMs at specific pressures. At the very least, most manufacturers will at least provide the CFM at a low pressure and another at a higher pressure. Many manufacturers will also provide a table listing how long it will take to inflate specific tire sizes from x psi to y psi. You can use all of this information as a relative measure of how fast a compressor will inflate compared to other compressors.
- Power Usage. One drawback to piston-driven compressors is they are power-hungry. Expect a solid performing RV grade compressor to draw 20 amps or more at 12V. It’s important to note this for proper operation. High current draw compressors will quickly draw down a battery if it is not being resupplied by a running engine, generator, or solar system. If you plan to use the compressor without a resupply source, you should consider units with lower power draws.
- Duty Cycle. The duty cycle is how long the unit can run continuously without being shut off for a cool down period. Piston-driven compressors generate a lot of heat, which can damage the unit if it is left running longer than its duty cycle. You’ll want to find a unit that can inflate your largest tire within the duty cycle time frame. Otherwise, you’ll have to take a break during inflation to let the unit cool. This can dramatically increase the time it takes to inflate a tire. Duty cycle is usually listed in minutes with longer being better.
- Valve Compatibility. Most units are designed for use with standard automotive type Shreader valves. If you want to inflate tires (like bike tires) with Presta or other valve types, you’ll want to check that the particular unit you are looking at can do that out of the box. If it can’t, what available accessories (if any) are available to work with those valve types?
- Hose Length. Each compressor will come with a section of hose for connection to whatever you are inflating. Make sure that the hose is long enough to reach where it needs to go. If you tow a trailer and your compressor needs to be connected to the running tow vehicle battery, then make sure the hose can reach the trailer wheels from the front of the tow vehicle. If it cannot, look for accessory lengths of hose that will extend your reach.
- Hose Type. There are two types of hoses available for these compressors. Coil hoses and straight flexible hoses. Which you choose is a personal preference. Coil hoses retract on their own for easy, compact storage. However, they won’t extend to be straight, so the hose has to be longer (and heavier) to reach a given distance. They can also turn into a mess if you happen to get them tangled up. Straight flexible hoses have to be manually rolled up for storage, and longer lengths can be unwieldy and hard to store.
- Hose connectors. Look for units with brass or metal screw type connectors on the ends of the hoses. These allow you to connect to standard Shreader valves as well as make secure connections to extension hoses if you need the extra length. The metal construction adds durability for long-term use. Look out for hoses that have the permanently attached bicycle-type flip lever compression ends. Those won’t allow reliable extension hoses to be attached.
- Included and Available Accessories. Look through what accessories the unit comes with and what else is available. Storage bags, hose extensions, Presta adapters, dually tire inflators, etc., are commonly available from most manufacturers.
- Construction. Look for a sturdy unit with quality construction. There usually isn’t a huge cost difference between the cheap junky units and the study quality ones. The small amount of extra cash buys much better durability and longer service life.
- Warranty. Always pick a unit that the manufacturer is willing to back up.
How to Use a Portable 12V Air Compressor.
Every unit may have slightly different operating instructions, so always consult your owner’s manual for the manufacturer’s official operating procedure. In general, the process is to connect the battery clamps to your battery terminals using a battery that has an active charging source like a running engine or solar charge system. Assuming you’re running it from your tow vehicle battery, once the battery clamps are connected to the battery then connect the hose to the tire or item you would like to inflate. Start your engine and turn the compressor on. Start a timer, or at least make note of the time you turned the compressor on. These can pump things up pretty fast so don’t walk away from it while it’s running. Once the item you are filling reaches the target pressure (or fills to full) then turn the compressor off. Disconnect the hose, disconnect the battery clamps and turn your engine off. Keep track of the time because you should never exceed the duty cycle of your specific compressor. If time runs out, simply turn the compressor off and let it rest a few minutes before restarting.
When you are all done, carefully return the compressor to storage. If you can, set it aside to cool off first, they can get hot, and keeping it in a safe place while it cools is always a good idea.
Why Should I Carry a Portable 12V Air Compressor in My RV?
I have done a lot of RV traveling over the years, and our Viair 88P portable air compressor is one of our most used tools. It is indispensable for inflating toys and bike tires. If you travel with kids as I do, there will be enough of that to justify the cost. However, the real use comes in RV maintenance while you travel. Improperly inflated tires on your RV, tow vehicle, or extra car are the leading cause of tire issues while you travel. That can include low fuel mileage, excess or uneven tire wear, or in the worst case, blowouts. These range in importance from benign annoyances to critical safety issues. We always include a tire pressure check as part of our pre-departure procedure when we travel. More often than not, at least one tire on our rig will need to be adjusted. Without the compressor, we would have to risk traveling with low tire pressure or find a local source that provides air that can also take in a large RV.
In the case of a tire leak, a portable compressor can be a lifesaver. With a slow leak, the compressor can be used to inflate the tire (as many times as needed along the way), so you can make it to a repair facility. This can save you from significant towing fees and from being stranded on the side of the road waiting for help to arrive. Of course, your spare tire can be used for the same purpose. However, I can tell you from personal experience that your spare will not always be enough. While traveling in the Pacific Northwest we experienced a blowout on the trailer. Shrapnel from the blown tire put a pin hole in the neighboring tire. We only carry one spare, and we were about 50 miles from our destination campground. By stopping every 10 miles or so and using the portable compressor, we were able to keep the second tire from deflating to a dangerous level. We hobbled into camp a little later than expected but without the need to wait for and pay for an expensive tow.
A quality portable 12V air compressor is a tool that every RVer should travel with. It brings with it the convenience of being able to inflate toys, inflatable boats, air mattresses, and tires on bicycles or your motorized toys without leaving camp. More importantly, it allows you to properly maintain your RV and tow vehicle tire pressures regardless of where you are located. In the long run, this will save you money and allow you to travel with greater safety.