What exactly is an inverter? Learn about DC/AC power supplies and how they work to power your devices with efficiency.

When you're on the go in your car, SUV, or RV, electronic gadgets like smartphones, GPS devices, and portable game consoles are often in use. These devices usually plug into your vehicle's power port, but you might wonder, "What is an inverter and why would I need one?"

If you're looking to power more advanced devices like a toaster, LCD TV, or even write an article on your laptop during a road trip, these gadgets require a standard wall outlet. To ensure you have the necessary power, you need a power inverter, not just a simple adapter.

Which type of power inverter is best suited for your needs? How do you go about installing one? And how does an inverter actually convert electrical current from one form to another? Don’t worry, inverter technology is simpler than it sounds. In this article, we’ll dive into the pros and cons of DC to AC power inverters.

What is An Inverter?

Power inverters are devices that change direct current (DC) – the kind of power stored in a car battery – into alternating current (AC), which is the type of electricity used in homes and needed for larger electronics to work.

Most cars and RVs rely on a 12-volt battery for power, although some heavy-duty vehicles may use a 24-volt battery. It's crucial to know your vehicle’s voltage because the inverter you choose must match your battery’s voltage rating. Regardless, the battery delivers direct current.

This means the current flows unidirectionally, from the negative terminal of the battery through the circuit and back to the positive terminal. This steady, one-way flow is why it’s called direct current. Batteries inherently provide direct current power.

Why is it necessary to convert DC to AC?

Direct current is certainly useful, but batteries usually only provide low-voltage DC power. Many devices, however, require more energy than what DC can offer. These gadgets are intended to operate on 120-volt AC, the type of electricity found in U.S. homes. AC, or alternating current, constantly alternates polarity, sending electricity one way through the circuit, then reversing and sending it the opposite direction. This process happens very rapidly, 60 times per second in most U.S. systems. AC works efficiently at high voltages and can be easily increased in voltage using a transformer, something that’s more difficult to do with direct current.

An inverter takes the DC voltage, boosts it, and then converts it into alternating current before sending it to power a device. These devices were originally designed for the opposite task — converting AC into DC. Since these devices can essentially be run in reverse to achieve the opposite effect, they were named inverters.

Next, let’s uncover how inverters perform their function of inversion.

Different Types of Inverter Uses

There are numerous types of inverters that help integrate various energy sources into our daily electrical setups. These include:

Each type of inverter offers distinct benefits and applications, demonstrating the versatility and adaptability of inverter technology in addressing the evolving energy demands of the world.

Turning Direct Current into Alternating Current

The first AC power inverters were electro-mechanical devices. Direct current would flow through a circuit with an electromagnet. When the current hit the magnet, it would activate it. This would pull a wire connected to a spring arm, forcing the wire to touch the circuit and redirecting the flow of current to the opposite side, which would turn off the power to the electromagnet.

Once the magnet was released, the spring would snap the wire back into place, allowing the current to flow on the other side of the circuit, once again triggering the magnet. These early inverters were known for producing a buzzing sound.

The Modern Use of Oscillators

Modern inverters now utilize oscillator circuits to perform the same function. They are built with transistors or semiconductors, eliminating the need for the mechanical spring arm that once alternated the current. However, the process is not as simple as it seems. Alternating current (AC) forms a sine wave, but the output from an inverter creates a very square wave, which is much different from the smooth, rounded wave of a perfect sine.

Certain devices are highly sensitive to the waveform produced by an AC signal. These include equipment that either transmits or receives signals, like audio or video devices, navigation systems, and sensitive scientific instruments. The square waveform from an inverter can be noticeable as horizontal lines on a television screen or as a steady hum or buzz through audio equipment.

Want a Smooth Sine Wave? It'll Cost Ya

To clean up the sine wave, a series of filters, inductors, and capacitors are used. Cheap inverters typically have minimal or no filtering, producing a very square wave AC. This may be perfectly fine for simple tasks like brewing coffee or powering basic electric motors. However, if you need a smoother sine wave, you'll have to opt for an inverter with better filtering. Of course, superior filtering comes at a higher price.

Inverters can become incredibly expensive, with some models costing thousands of dollars, especially if you're seeking an inverter that provides a smooth sine wave. The good news is that with a sufficiently large budget, you can find AC power inverters that generate nearly perfect sine waves. In fact, some high-end DC to AC inverters (such as modified sine wave inverters) can produce sine waves that are even smoother than the AC power from your household grid.

Check Your Volts

With so many options available, how do you choose the right inverter? Should you go for a solar inverter or perhaps a mechanical one? The first thing to consider is matching the inverter's voltage with the battery you'll be using to power it. Most commonly, you'll use a 12-volt battery, so you'd want to select a 12-volt inverter to ensure compatibility.

Next, you'll need to assess which devices you'll be powering. Each device should have a label indicating the wattage it requires. The inverter you choose must be able to handle a wattage rating that exceeds the total wattage of all devices you'll run at the same time.

For example, if you're planning to run a 600-watt blender and a 600-watt coffee maker simultaneously, you'd need an inverter that can handle at least 1,200 watts. However, if you know you'll never use both devices at the same time, you could get by with a 600-watt inverter.

Watts, Peaks, and Surges

Unfortunately, things are not always as straightforward as they seem. Devices with electric motors, as well as certain televisions, consume more wattage when they first power up compared to their normal operating wattage. This surge or peak power usage should also be indicated on the device’s label. Many inverters also have a peak wattage rating, so ensure that the inverter’s peak capacity is greater than the device’s peak wattage.

Microwaves present a unique case. For instance, you might think your microwave uses 500 watts, but this is actually the cooking wattage. The power wattage could be double that. Always verify the device’s label to ensure accurate wattage details.

Choosing an inverter for an air conditioner can be equally challenging. It’s important to determine the right AC capacity for your space and factor in energy efficiency ratings like EER or SEER to help predict potential savings on your electricity bill.

If you’re planning to run your inverter through your car’s cigarette lighter, keep in mind that you won’t be able to power high-wattage devices. Attempting to draw more than about 400 watts from the cigarette lighter could cause it to fail and might even pose a fire hazard.

Don't Forget About Wave Output, Voltage

The final feature to consider is the wave output of the inverter. If you plan to power equipment that is sensitive to square waves, be sure to choose an inverter with a "perfect sine" wave output.

Be ready for a bit of sticker shock — a perfect sine inverter can cost nearly ten times more than a similar wattage inverter with a modified sine output. Modified sine waves mean the current has been filtered to avoid a square wave, but it still isn't completely smooth.

Inverter Installation

Installing an inverter is typically a breeze. Most inverters, especially smaller, lower-wattage models, are "plug and play". They come with a cable that plugs into your car or truck's cigarette lighter, making them portable and easy to use without any need for mounting.

If you opt for an inverter with higher wattage capabilities, proper installation becomes more crucial. While inverters below 400 watts can still use the cigarette lighter, anything above that requires a direct battery connection. The inverter's input cables feature clips that attach to the battery terminals, much like jumper cables. For permanent installations, the cables can be bolted directly to the terminals.

The inverter itself can be installed anywhere, though it should be placed in a well-ventilated area. Inverters tend to generate heat, and they include cooling fans and heat dissipation fins to manage it. Larger, heavier models even come with mounting holes, allowing them to be bolted onto any surface.

For a permanent setup, bolting the inverter in place is usually a good idea, but it's not strictly necessary. You can just place the inverter securely, clip the leads to the battery, plug in, and start enjoying your newfound power!