An AC/DC power inverter is a device used to convert AC, or alternating current, to DC, or direct current. These types of devices are commonly used to convert energy from a car battery to allow electronic devices to be powered inside a car.
In general, there are two types of energy: AC and DC. AC flows between the negative and positive electrical poles, and DC flows from the positive to the negative electrical pole with no break. Direct current is naturally occurring and is re-created in batteries. Alternating current is artificially generated and is used in most public utility systems, so it's what is provided when a device is plugged into a wall socket. An AC/DC power inverter is used to allow AC-powered devices — typically, those that usually plug into a wall — to work from a DC power source, like a battery.
Power inverters are often used to run small devices, like music players, seat warmers, and satellite radios, from a car battery. Those devices use AC power, so the inverter changes the DC power provided by the battery so that it can be used to run them.
The AC/DC power inverter was invented to address this specific need. It is built into the car's electrical system and works by modifying the wave type from alternating current to direct current. This conversion must be contained within a specially constructed container to ensure that the inversion does not affect other devices or systems.
There are two key components to an inverter: wave and wattage output. The wave is a description of how electrical signals look on an oscilloscope. DC power looks like a straight line, while AC appears as a sine wave. Different types of inverters change the straight DC line to be closer to the AC wave, sometimes creating what appears to be a blocky, square wave and sometimes creating the smooth curve of a true sine wave.
An AC/DC power inverter that creates a smoother wave works much better than a square wave inverter. Newer inverters can now work with either modified square or sine waves to create the required power switch. In practical terms, the difference between the two types is very minor and usually only affects high end equipment with very specific requirements.
The wattage of the power inverter is critical in determining how many devices can be used simultaneously without risk of overloading the system. People who are considering buying one should check the watts value listed on the product packaging before making a selection. The difference in price for more watts is often minor and may be outweighed by the benefit of being able to use a wider range of devices with the inverter.