What Is a Power Inverter? – How Does It Work? | Do You Need One?

Last modified on May 11, 2022
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power inverter in a car dash

Do You Need One? A power inverter is a device that takes DC power as an input and converts it into conventional AC output.

You can use this AC output for electric power devices, including appliances, lights, ovens, refrigerators, TVs, computers, etc. You need to connect this inverter with a battery and plug in the AC device you wish to use.

If you use an inverter as a portable power source, you need to understand its working and application first. The inverter is a great tool to draw AC power from a DC output battery anytime, anywhere you want.

Working of A Power Inverter

When you look at the graph of the output of DC power, then you will find it to be a straight line. This straight line represents the continuous and steady flow of electric charge that is unidirectional.

how power inverters work?

On the contrary, the AC source has a fluctuating charge flow that keeps changing its direction after one every half cycle. Therefore, the graphical representation of AC power output is a sine wave that makes a smooth valley with peaks of identical width and height.

Power inverters are designed to take DC power as input which undergoes a physical system that forces it to change the direction of charge flow.

The DC power source is converted into AC power with inverters. However, these are rough oscillations that, on graphical representation, create a square waveform.

While the traditional AC waves are typically round, these inverters are supplied with some filters making the waves smoother. You can use this AC source with a wide range of electronic devices.

Common Sizes

Commonly, you can find these power inverters in three sizes – 1000 watts, 3000 watts, and 5000 watts.

An inverter with 3000 watts of power is the most widely used size offering perfect power output among these three options. A 3000 watts inverter is neither too powerful like 5000 watts nor too weak like 100 watts; it’s just the perfect option for universal use.

For those looking for a little more push, there is an option of 3500 watts. Before choosing the size of your inverter, consider the amps and watts of appliance you want to run (you will find this information labeled in the product description segment).

If you want to stay on the safer side, it’s best to go a bit higher than your expected power range (generally, it’s good to buy an inverter with 20% more power than your highest load).

Determine Peak (Starting) and Continuous Load: it is vital to calculate the amount of power you need to run any appliance or tool (basically any combination of different tools running simultaneously) to run it start (start load) and then follow by continuous running (continuous load).

Types of Power Inverters

Power Inverters for Hospital Carts

Many healthcare facilities use inverters designed for use with medical equipment by adding them to mobile medical carts. Using these inverters allows health experts and technicians to follow their treatments, run diagnostics and use their special equipment without any problem.

An inverter about to be used for hospital and medical equipment must be UL 60601-1 compliant.

Power Inverters for Ambulances/EMS Vehicles

Many special inverters are completely reliable and safe as a portable power source in EMS equipment/ambulance.

An inverter rated as UL 458 compliant will work perfectly in medical vehicles. Tripp Lite offers one of the best inverters with an integrated charging system and easy installation.

Power Inverters for Sensitive Electronics

Several electronic devices like ATMs, tools with variable speed, laser printers, components of audio-video gadgets, active PEC-powered computers, equipment for networking work on AC power in pure sine waveform. Microprocessor-controlled and stable power sources in sine form help run your device in a cooler state and increase its lifetime.

With a stable power source, you can ensure safety against any malfunction or degradation of performance.

Ratings of An Inverter

The ratings of an inverter are a representation of its power output.

Commonly inverters are rated in watts power, calculated by multiplying the current in amperes with its potential drop. The power inverter is tested using different tests like AC input voltage, frequency, IMD, and others.

The ratings of an inverter are divided into three categories:

  • Continuous Rating
  • Limited-time Rating
  • Surge rating

Some of these tests are mandatory, while some are recommended. First, the AC input is tested at a high level to ensure that it will not overheat or damage any connected device.

Next, the DC output voltage is tested to ensure that the power produced by the inverter is adequate in case of an emergency. Finally, the output voltage and frequency are tested on a low level with a special multimeter and external test equipment, respectively.

Surge Rating

The surge rating is the most important and most common test of a power inverter.

This rating is the maximum capacity of an inverter to handle the amount of current or voltage required when it overheats, catches fire, or has an electrical failure. Most electrical devices are not powerful enough to handle surges, so an inverter needs to be able to handle them.

But at the same time, they have enough capacity to take care of normal daily use.

The surge rating of a power inverter refers to how much an inverter can handle when operating at high voltage or high current levels during a short period of time-usually less than 10 seconds.

Continuous Rating

The continuous rating is the amount of wattage that a power inverter can produce continuously without any failure. The continuous rating does not mean that you can connect any device to it and use it continuously.

There is no need to worry about overheating or damaging anything while using such inverters. In some cases, it will damage your appliances, and in some cases, it can even damage your inverter.

It is best to check the specifications of a device before using them with an inverter.

Limited-Time Rating

The limited-time or surge rating is the amount of wattage that an inverter can continuously generate for a limited amount of time.

It is also known as the duty cycle of an inverter. The duty cycle depends on various factors, including its state and condition, the type of load connected to it, external temperature, and the type of battery connected to it.

Duty cycle ratings are represented in percent, where 100% duty cycle means that there is no limitation on using an inverter. 30-Minute Rating

This Rating is a very important test. It states the maximum power that an inverter can deliver for 30 minutes.

If any appliance connected to an inverter does not work properly for more than 30 minutes under normal conditions, then this means that the power inverter has failed and needs to be replaced or repaired. It is important to remember that there is no warranty for these devices, so if any damage occurs, there is very little that you can do about it.

Frequently Asked Questions

Do power inverters drain car batteries?

In simple words, yes, it is indeed possible.

However, when you take a deeper dive, you will find this process much more complicated. For example, suppose the battery you are using is in good condition and charged to full power.

It is possible to drain the battery completely without starting the car by using 400W batteries in such conditions.

If you want to get more accurate and find how long a battery will last with any specific inverter, it’s time to do some mathematical calculations.

Start by taking the wattage of the inverter you are using (400W) and then divide it by the given battery’s voltage (12V). You will get the amps your battery is drawing.

In our case, by dividing 400W with 12V, we get 33.33 amps. However, any given inverter is only 90% efficient when converting power.

This means here, this 400W inverter is drawing 37 amps.

As generally seen, a normal car battery comes with 80 minutes (at 25 amps) of reserve capacity. In our situation, this 400W inverter is drawing 37 amps, which means it will take around 54 minutes approx ((80 minutes x 25 amps)/37 amps = 54 minutes.) to drain the battery completely.

This is the sole reason why it is recommended to turn on your car’s engine almost every 30 minutes whenever you are using a power inverter, as it will maintain the battery charge.

Can I power my home using my car and a power inverter?

Yeah, of course! The first thing you have to do is know the wattage of all your electronic devices, calculate your daily wattage, and buy one that can handle that much wattage.

It will surely help you buy a perfect inverter for your home and save you from extravagance. Keep your inverter away from dust and bright sunlight as an inverter is not water-resistant.

You can easily connect your inverter to the vehicle’s battery using jumper cables and alligator clips available on the online store. There is another way to connect the inverter to the vehicle, and that is the use of a ring terminal that fits securely over the post of the inverter.

Now use an extension cord of under 200 feet in length to connect the appliance with the inverter. However, an extension over this length will lead to significant signal loss.

An ideal thing to do here is to run your car for around 10 minutes every hour to keep the battery charged.

This way, the inverter will still work even when you turn the car off (if you have not depleted the car’s battery).

What kind of battery should I use with my inverter?

Generally, the 12V batteries used in cars are preferred for use with normal power inverters.

Additionally, there are many variants of batteries, including 24v, 36V, and 48V, in the market. However, high-power batteries have applications in a heavy-duty industries where high wattages are required.

If you are finding a battery to use with your inverter, just make sure to match the voltage capacity of batteries with the inverter.

Another option is a deep cycle battery that is almost identical to your normal car battery. However, unlike normal batteries, a deep cycle battery will offer you a longer runtime and uninterrupted working until they reach 80% battery level.

So whether you are looking for inverter batteries for boats, RVs, or off-grid renewable energy sources, using a deep cycle battery with an inverter is your best bet. The best part, these batteries offer uninterrupted power support right up to zero battery level, where you can recharge them again.

Using a battery alone will not work, and you need some complimentary stuff like a fuse and its holders.

Among all the options, the ANL fuse makes for the best option as you can easily use them by splicing them into the positive wire of the battery pack.

What type of cable should I use to connect batteries?

When you buy an inverter, you do not have any type of connection cable.

So you need to choose your cable type, preferably under 10 feet. If you want better results, look for SGX-type cables to connect batteries with your inverter.

SGX is the cable used to connect and ground a car’s battery with its electronic system.

What is the difference between an inverter and a generator?

Generators can operate on gasoline, diesel, or propane to create electricity. Tools, electronics, appliances, and other equipment require AC power, which can only be provided by an inverter.

When huge amounts of electricity are required over a lengthy period of time, a generator may be a preferable option. An inverter/charger, on the other hand, is a better option in terms of cleanliness and environmental friendliness.

It is ideal for usage indoors or in residential areas because to its low noise and lack of noxious fumes. If you have a generator, an inverter/charger will allow you to conserve gasoline by shutting down the generator for short periods of time while keeping your equipment operating.

Does an inverter provide surge protection?

Yes. An inverter’s AC output is pre-conditioned before it gets to your equipment since it transforms DC electricity to AC power. You can safeguard your equipment from power surges and line noise interference by using an inverter, which delivers consistent output voltage and frequency.

Can an inverter power a refrigerator or freezer?

Yes, but don’t forget one crucial aspect. While a refrigerator or freezer cycles on, it will consume a strong start-up surge of electricity, several times the watts it needs when operating continually. Check your inverter’s surge capacity.

As a general guideline, be sure your inverter can sustain a peak surge of 500-750 watts for a refrigerator and 500-1000 watts for a chest freezer before installing one of them.