The Difference Between a Low Cost Power Inverter and the More Expensive Models

Have you ever wondered why some inverters cost much more than others of the same power. I will briefly describe one of the main differences between a low cost power inverter and a high cost item. 


Finding a power inverter to convert DC power to AC may seem like it should be a simple task, but when you start shopping for a power inverter for your personal use, you’ll soon find that many choices will confront you. With prices ranging from less than $25 to well over a $1000, it can be difficult to know what features are important and how to choose a unit appropriate to your needs.

While wattage you need and how you will be connecting the unit to your power source are items to be taken into consideration, another item that you should take into account is the inverter’s wave form output. There are two general types of power inverters: true-sine wave or modified-sine wave (square wave). True-sine wave inverters produce power that is either identical or sometimes slightly better to power from the public utility power grid system. The power wave when viewed through an oscilloscope is a smooth sine wave. Modified-sine wave and square wave inverters are the most common types of power inverters on the market. Modified-sine wave power inverters produce a power wave that is sufficient for most devices. The power wave is not exactly the same as electricity from the power grid. It has a wave form that appears as a choppy squared-off wave when viewed through an oscilloscope. What does that mean to the everyday user? Not much. Most household electrical devices will run perfectly fine on either type of wave form. 

Most of our customers who are using a power inverter to run a laptop, a/c cell phone charger, fan, or camera find that a modified-sine wave power inverter that operates through the cigarette lighter socket the easiest to use. 

We usually suggest choosing power inverters that are rated under 300 watts when using the 12-volt cigarette lighter socket found in most vehicles. We suggest this because after reaching 300 watts of draw on the inverter, the fuses in your car will begin to blow. There are several units available on the market powered between 100-200 watts that plug directly into the cigarette lighter of a vehicle. It has only one outlet, but since plugging it into a 12 volt socket is all that is required for operation, it can’t be beat for ease of use. These little units usually supply around 150 watts of continuous operation and normally have a built in surge protector.

Square wave units or your low cost power inverters fall into the following three groups: 

500w or less For household appliances, TVs (up to 19″), VCR, desktop computers, other mobile office equipment. Most of these connect via a 12-Volt plug. 

501-999w  For household appliances, large screen TVs, 5-amp power tools, and bread machines. Most such inverters are connected directly to the 12-volt battery and have three or more grounded outlets for powering several products at the same time.

1000-3900w For household appliances, larger power tools, microwave ovens, toasters, and hair dryers. All of theses inverters are designed for direct connection to the battery network and can generally supply 750- 2500 watts of continuous power. 

The problem with wave form only comes into play when specialized pieces of equipment need to be powered. Here are a few devices which could have problems when they are connected to an inverter producing a modified-sine wave signal: oxygen concentrators, fax machines, laser printers, high voltage cordless tool chargers, equipment with variable speed motors, electric shavers, and garage door openers. For most all other applications you can go with the low cost power inverter.

In closing, it is really not necessary for the average user to go with the true sine-wave unit. The modified sine-wave found in most low cost power inverters will be sufficient take care of your applications.