How to Choose an Air Compressor

There’s a huge range of air compressors on the market. Larger units, powered by a mains supply of petrol or diesel fuel, are found in construction sites, factories and processing facilities, workshops and agriculture to power things like air tools, pumps and irrigation systems. There also might be one just outside your window, and spooling in cool air from the air con. In addition, a compressor is what keeps food in the fridge fresh and cooled by circulating the air.

But you can also find small, portable compressors that come in handy when you’re off-road or camping. Here portable 12volt air compressors are simple tools used to inflate tyres, set up camping gear, clean the campsite or bring life into a deflated rugby ball. These types of compressors can run off the car’s battery, or if you don’t feel like running that risk, off a secondary battery that most of us have anyway when we’re far from home.

For primary use, getting tyres back to the right air pressure after a long bout on more technical terrain, a 12V compressor is more than up to the task. It will inflate tyres quickly, and with the right gauges, to the correct PSI. You won’t be using this to power more demanding air tools, like impact guns or hammer drills. They just won’t be powerful enough, and (excuse the pun) would soon run out of puff.

What to Look for When Buying Your Next 12V Air compressor

Not all small compressors running on 12V DC power are created equal. There are considerable differences in prices among different models. This all boils down to size and overall power, operational speed, featured accessories and the care taken in the build.

General Use vs Heavy Duty Air Compressors

Just like their bigger brothers, smaller 12V compressors will be tuned for a specific task, or set of tasks, and built (and sized) as such. Small, light, general use compressors can more than handle inflating any type of tyre in a reasonable amount of time. They come with a hose and connectors to fit different types of valves.

But that’s about it when discussing their abilities. Where more air is needed, and in higher pressure, a heavy-duty compressor is what you want. This can be used in adjusting things like airbags in air suspension, or for powering smaller air tools, like nail guns and pressure cleaners.

Power Rating – HP

To get the work done, air compressors will have different power ratings that impact the amount of air they can push into the tyre, and the pressure of that air. Horsepower figures range from 2 to 10 hp, and even less powerful models will be enough to inflate a bigger tyre.

Airflow – Litres Per Minute (LPM)

This is the volume of air the air compressor can push at a defined pressure (usually 100 PSI). For countries using the metric system, like Australia, it is denoted in Litres Per Minute, and Cubic Feet Per Minute (CFM) elsewhere. The higher rating means faster inflation times, as well as efficiently powering smaller air tools. Look for compressors with over 100 LPM for quicker results, and more versatility. A compressor with an included air tank will also be able to provide higher volumes of pressurised air, so run times are longer.

Air Pressure – PSI

How fast you get a tyre inflated also depends on the air compressor’s maximum air pressure rating in Pounds Per Square Inch, or PSI. This will also determine whether the pressure is sufficient to run air tools, like pressurized water jets for cleaning your 4WD after a run in the bush. Bigger air tools will push the limits of most 12volt air compressors, so look for at least 150 PSI if you intend to use the compressor for more than just tyres. This comes at a slightly higher cost, but the added convenience pays off.

Power Sources

Most air compressors can run off a !2V cigarette lighter socket, some will include packaged clamps to attach directly to the car or secondary battery, while others can have rechargeable batteries that also fit in cordless tools. Those sourcing power from 12V sockets tend to be slightly cheaper, but directly clamped compressors are generally more efficient with a higher current draw, and as such they’re more powerful and get the job done quicker. If you use a lot of cordless tools, then a sensible choice might be a 12V compressor running on rechargeable Li-Ion batteries.

Duty Cycles

This is the time a compressor can operate at a set air pressure. Higher duty cycles mean that you can get more work done in one bout. Duty cycles are directly related to airflow and air pressure, so 12V compressors with included tanks should last longer, work consistently without the need for downtime, and be quicker at what they do.

Hoses and Attachments

The length of the hose can make or break a compressor. Look for hoses that are at least five metres long, and fitted with a precision gauge to measure air pressure. Alternatively, you can get separate gauges to get a better picture of the pressure at which the tyres are inflated. Also, look for longer alligator clamps in clamped 12V air compressors.

Most kits will have enough leverage for longer vehicles, but longer hoses and clamps are useful in inflating tyres in towed vehicles, like caravans and trailers. Accessories like interchangeable nozzles, built in regulator valves for auto-shut off and carry cases help in usability, safety, and storage.

Size and Weight

The 12V compressors are small, portable, and easy to use. They won’t take up much space in the boot, canopy, tray, or tub, but are indispensable tools that will see regular use. Smaller units weigh less than 10 kilos, while faster and more efficient compressors, with better build and an included tank, hover around 15 kilos if weight and handling are a concern.