Air compressors are extremely useful tools that are common to find in homes and shops across the country.

They enable their owners to do things like tire inflation, painting, and driving nail guns. One of the most common things air compressors use is to air up tires. So, a lot of people are wondering if a car should be running when using an air compressor.

While it may seem reasonable to assume that it would be best to run an air compressor with the engine on to prevent draining your battery, that is actually incorrect. In fact, most manufactures actually recommend that you don’t run your engine while running an air compressor. 

The reason for this is the fact that 12 volt air compressors are, well, designed to run on 12 volts. The problem is, your alternator will supply your battery with about 14.5 volts to keep it charged.

So, it’s best to run a cigarette lighter powered air compressor with the engine off. They simply don’t consume enough power to be able to kill your battery when filling up a single tire.

What Are The Things That Can Drain Your Car Battery?

A dead battery can be more than just an annoyance. Depending on your situation, a dead battery could cost you your job or cause problems in other complex ways if you are not able to get where you need to be. Here are some of the most common reasons why a vehicle battery will end up dead:

The Parasitic Draw

The number one reason a car battery will die is due to parasitic draw. A parasitic draw happens when there is a failed component or bad wiring somewhere in your system. In some cases, the battery itself can be the parasitic draw.

So let’s say you have a radio with a burned out component. In this example, let’s say that your left speak channel stopped working. Depending on how it fails, the chips responsible for producing sound in the left channel may be drawing a little power from the system as a result of their failure. 

In these situations, you will only be annoyed by the lack of sound from the left side of your car during normal operation. This is because while the engine is on, the alternator is always charging the battery. But in this example, the moment you turn off the key, you risk draining your battery.

Headlights 

Headlights are one of the heaviest-weight components of your car when it comes to electrical usage. Depending on the health and size of your battery, just a few minutes with your headlights on can cause your battery to drain to the point where it’s no longer able to start your vehicle.

Extreme Temperatures

Regardless of what type of battery technology it is, extreme hot or cold temperatures will negatively impact its performance. While newer batteries are more resistant to wild temperature swings than old ones, it still affects them. 

As a general rule of thumb, the colder a car battery is, the last amperage it is able to provide. That is why they are rated in Cold Cranking Amps.

Loose or Corroded Battery Terminals

Car battery terminals are often the culprit when it comes to a drained battery. If the terminals are loose, you may be able to start your car, but as you drive they can become disconnected and prevent the battery from being charged.

Old Car Battery

Even if nothing else is wrong with your vehicle, at some point, the battery will die. Yes, they can last for years but when they go, they go. Remember, the more times you let your car battery die from running the radio or headlights with the engine off, and the more extreme temperatures that your car battery is suggested to will impact its life and performance.

With that being said, a car battery generally lasts about 5 years if properly cared for.

Bad Alternator

As the car depends on the battery to start the engine, the battery depends on the alternator to keep it charged. So, if your alternator goes out, it will not charge your battery at the rate it’s supposed to. In fact, if your alternator completely fails, it wont charge your battery at all.

So, Should The Car Be Running When Using An Air Compressor?

As you can see from the list above, there are several things that can cause your battery to die. Fortunately, running a 12 volt air compressor or mini air compressor, that was designed to operate from an electric cigarette lighter is not one of them. 

This is because it simply does not take long enough to air up a tire and car air compressors do not consume enough power to completely drain a car battery. You do, however, run the risk of burning up your air compressor if you run it at a higher voltage than what it was designed to operate at. 

Why Is My Car’s Voltage Higher When It’s On?

Passenger cars and light trucks are designed to operate with 12 volt batteries. The thing is, however, in order to keep a lead acid battery charged, you have to put more than 12 volts into it. 

This is where your alternator comes into play. An alternator is a device that converts mechanical energy into electrical energy. Alternators put out somewhere between 13 and 14 volts to keep your 12 volt lead acid battery charged. 

While all your car’s electronics are designed to operate at both of these voltages, incorporating that level of voltage compatibility into any system often costs more than not doing so. 

For this reason, most low-cost air compressors are designed to run at just 12 volts.

Frequently Asked Questions 

Can I Run A Vehicle While The Inflator Is Operating?

You might be able to but you really shouldn’t do so. Even if you have a weak, low cost car air compressor, it’s not going to take that long to inflate a tire.

So, you are going to be able to air up your tire far before your battery goes dead. In contrast, your air compressor may not be designed to operate at the higher voltages that are experienced when an engine is running.

Can A Car Run On Compressed Air?

No. With all of our current technology, the simple fact is that there is just no way to store enough compressed air in the volume of a vehicle to be able to propel that vehicle forward.

Either much higher-pressure air tanks need to come out (which would require radical breakthroughs in material sciences) or a far lighter material than steel or even carbon fiber would need to be used to make the car light enough. Again, a major material sciences advancement would have to take place first. 

So, unfortunately you won’t be seeing any compressed air-powered cars driving down the highway any time soon.

How Does A 12v Air Compressor Work?

A 12V air compressor works just like any other air compressor. There is an electric motor that is used to turn a compressor. The only real difference is that 12V air compressors run on 12 volts DC instead of 120 or 240 volts AC. 

Another difference is their size. Because a 12V air compressor is not very powerful, it doesn’t need to be very large, as it would take an unacceptably long amount of time to fill a large air tank.

Can AC Drain Car Battery?

In most cars, the AC compressor is powered by a belt. So, that means the AC cannot even operate if the engine is off. So, because of this, there is no way for the air conditioner to drain your battery.

What Is The Difference Between An Inflator And A Compressor?

They both work the same, but an inflator has much less power than a compressor. Also, inflators generally do not use any kind of storage tank.

Can I Sleep In The Car With AC On?

Yes. If you have enough fuel and your car doesn’t overheat or anything like that, it will be totally fine. The AC in a car does not directly produce any toxic gases. It does, however, require the engine to be on. So, if you do plan on sleeping in your car with the air conditioner on, just make sure you are not in a closed garage and you will be good to go.

Conclusion

Air compressors are among the most useful and most versatile tools in your garage. They let people perform tasks that they otherwise would not be able to such as painting, driving nail guns, and of course, tire inflation.

When it comes down to it, however, most people just need an air compressor to air up their tires from time to time. For this reason, small, portable, 12V models are available. 

You may feel like you need to keep the engine running so your air compressor does not kill your battery in the same way running your radio for too long with your engine off will. Most 12V car air compressor manufacturers, however, recommend not to have the engine running while operating an air compressor. 

This is because alternators charge a battery at 14.5 volts. This causes all the other electronics in the car’s system to switch from 12 to 14.5 volt operation which your air compressor is more than likely not capable of. 

We hope this article helped answer any questions you may have had regarding whether or not a car should be running when using a portable, 12 volt air compressor.