12-Volt Air Compressors – What To Look For, How To Use Them

How many times have you been driving, got a flat, changed the tire to your spare, only to realize that it has been there so long that it too has gone flat? Even if that is only once, it is one time too many. However, on the other hand, how many times have you wanted to do something like DIY and needed compressed air, but you only have your vehicle? Well, that is why, in this article, we will look through what to look for in a 12-volt air compressor, and a few of the other options that you have available. We will also cover the basics of how to use them. 

What To Consider When Buying A 12-Volt Air Compressor

Of course, the first thing that you need to do before spending any of your hard-earned money is to make sure you are considering all of the variables that come with them. While you may think that all air compressors are the same, they are not. Yes, they all compress air for you, but they don’t all do it in the same what, and nor do they all have the same features. 

What Will You Use The Compressor For?

Tires are the initial thought when buying any 12-volt air compressor. That is because you are going to be able to use it in your vehicle, and your tires need air. However, when you are spending your money on something, you need to know what it is capable of. Therefore, you may want it solely for tires, or you may want it for other things, too. 

You may already know what you want it for, but if you are unsure, here are a few of the options that you may have when you buy a 12v air compressor:

• Tires. – Car, truck, bikes, etc.
• Balls.
• Swimming accessories
• Camping. – Airbeds, PVC boats, etc. 

Most of the 12v compressors available on the market will cover these things. However, there are some, more specialized variants available that can do more than that. For example:

• Air tools.
  • Pneumatic impact wrenches
  • Drills
  • Grinders
  • etc.
• Spray guns
• And more

Of course, there are more things that you can do with some compressors. However, you need to decide what you are likely to use it for, as you do not want to buy one that will not fulfill your requirements, and nor will you want to spend more than you need to. 

If you have tools, I would highly suggest that you buy one that is capable of running them, even if you think that you do not need it. 

Does It Have A Tank?

On the same note as using it for tools, you may want a compressor with a tank or a receiver. Having one can be very useful for things such as horns, or extended use of tools. However, again, it is not only the fact of having a tank that is important. You also need to think about these aspects:

• Tank capacity
• Are they attached?
• Is it portable?
• Can you use it without the receiver?

One thing that you need to consider is that most of the compressor tank combos, are onboard systems, meaning that you have to mount it somewhere, and hardwire it to your vehicle. With a little preparation, though, you can turn them into portable units. We will not be covering that in this article, as it is a bit more in-depth, and you need to have some knowledge about electrics to do it. 

Maximum Pressure

If you have ever looked into pneumatics at all, you will see that there are very few times that you will need over 100psi. Even tools run on that pressure. The problem that some people have thought is that almost all compressors will have a maximum output of 150psi+, leading you to believe that they are all capable of your requirements. 

Unfortunately, that is not the case. I have seen extremely cheap compressors that are “capable” of reaching 150psi, but they will never get to even a percentage of that pressure. 

When we come to the recommendations, we will have gone through and made sure that the compressors are capable of what they state. But, if you go looking for them yourself, ensure that you do check. 

Power Supply

Although we are focusing on 12-volt air compressors in this article, you may still want to know that the one you buy can run off other power supplies. Furthermore, you want to know how it will attach to the vehicle when you want to use it. 

Most people reading this are going to have an in-vehicle 12v power socket that you can use to power them. However, some vehicles don’t have them, so you will need to know if you have one or more in your vehicle before buying one that only runs from them. Alternatively, you can buy one that has a battery connection, or one with both.  Others have a twin motor configuration, which will also allow you to plug your compressor into the mains if you want to use it in the house, shed, or garage.

Alongside the power supply, you need to consider the length of the power cable. You will want to ensure it is long enough to reach where you need it to. That is especially true if you are going to need it for the tires of a larger truck, if you need to use it away from your vehicle for camping equipment, etc. 

Auto Cut-Off

Gone are the days of keeping your watchful eye on the gauge, making sure it does not over inflate your tires. Now you have the option, like at garage forecourts, to set your required pressure and wait till it stops. This option is certainly something that you should consider, as the benefits far outweigh the risks of over inflation. 

There are some sites that I have seen, and even some item descriptions, that claim you can just turn it on and leave it, even if you do not know what pressure you need in the item you are inflating. Unless I am completely behind the times, that is simply not true. You need to know what pressure you need in the thing you are filling to set it up before you start.

Gauge Type

If you want a compressor that will turn off automatically, you are limited to owning one with a digital gauge. However, not everyone is a fan of them, so you need to decide between having a digital or analog gauge and the pros and cons that go with it. 

Analog Pros

• Easy to see no matter the lighting – if you have a torch.
• More robust.
• Sometimes more reliable.
• Often easy to replace.

Analogue Cons

• Hard to see in the dark if you have no torch. 

Digital Pros

• Easy to see in any lighting.
• Ability to have an auto cut-off function.

Digital Cons

• Hard to replace.
• It can be prone to faults.

Weatherproof 

Not all compressors are weatherproof, although nowadays, most are. All that that means is that you need to check that it can withstand the weather that you are going to be operating in, whether that is the extreme rain or very high or low temperatures. 

Accessories

Some compressors will have more accessories in them than others. Some examples that you should look out for are:

• Flashlight
• Carry case
• Tools
• Hose type
• Spare fuses (for compressors not powered by the internal vehicle power socket)
• Inflation speed
• Cordless

I won’t go into too much detail about these things, as they are pretty self-explanatory. However, you should consider them when you are looking for any 12-volt compressor. 

How To Use A 12V Air Compressor

Using 12v air compressors is a straightforward task. 

1. Check if there is a power switch. (if there is, ensure it is off)
2. Fit the correct attachment to the hose for what you are inflating/tool you are using.
3. Attach it to the tire/tool/inflatable, etc.
4. Connect the power (in-car socket, battery, wall socket)
5. Turn it on (you may need to set the required pressure, then press a “go” button, or you may need to toggle the power switch. If it is an analog gauge type, it will start running as soon as you turn it on)
6. Keep an eye on the pressure or use the tool.
7. Turn off the compressor when the desired pressure is reached (auto shut-off will turn off on its own)
8. Remove the power
9. Remove the connection to the tire, tool, etc. 

Repairing A Compressor

If you have ever learned anything about compressors, you will know that in these smaller, 12v compressors, there is not a lot to go wrong with them. Even the larger ones are pretty similar, but they have the receivers with them to maintain too. 

The most likely faults you are going to encounter are all pretty simple:

Power cut out

• If your compressor has suddenly stopped working, you first should check your power supply. – The easiest way to do that is to plug something else into the 12v power socket. 
• Next, check for broken wires. – Providing you have power to the socket, it is not uncommon to break the cable by shutting it in the vehicle door. 
• Reset the overload switch. – Some compressors will have an overload switch that will trigger when the unit gets too hot, or too much power is drawn from a broken wire, etc. Reset it if it has activated. 
• If you still have a power problem, you probably own a digital gauge compressor, and the circuit board has a fault. In this case, it is probably more economical to pay for a new compressor, unless you have electronics experience. 

Reduced Pressure/Flow

• Check for kinks in the airline. – Kinks in airlines are one of the most common reasons for reduced pressure and flow; they are also the easiest to rectify. 
• Check for air leaks. – Some compressors are pretty loud, so hearing a leak, especially a small one, can be difficult. Use diluted washing up liquid to pour over connections and hoses while the compressor is running. If you see bubbles, you have found the leak. (Do not apply cold water to hot metal parts, it can cause cracks.) The two leading causes are:
  • Split hose. – Replace the hose.
  • Joints are working loose. – Remove the connection, apply PTFE tape, replace, and recheck. 
• Check for a filter. – If you have a filter, it may be blocked up. Clean it if there is one. 
• Check for a pressure relief valve. – If there is one, it may be operating at a lower pressure than what it should. That is often because something has got inside it and is holding it open. Other times, you may find the spring is worn, or the valve seats are pitted. However, they are usually hardened steel ball bearings and faces, so this is uncommon compared to dirt and debris, or spring failure. 

Other faults are likely to be more expensive and time-consuming, thus meaning they are probably not economical to repair. 

Conclusion

12v air compressors are useful items to have. However, as with any other machinery, you need to ensure you look after them properly. Remember that, if you want to use tools, you will probably need to have a receiver to hold the air pressure and volume. 

Check the rated duty cycle. A lot of compressors are made with cheap aluminum parts, and they can deteriorate from the heat if you run them for too long. If you need a compressor that will run for a long time, ensure you ask the question.

Finally, do not buy cheap! You will regret it.