How Do I Convert 12 Volt DC to 120 Volt AC?

by Michael MacLeod

Converting 12 volt DC power to 120 volt AC power is generally a two-step process. You have to first convert the 12 volt DC power to 12 volt AC power, and then run the 12 volt AC through a step up transformer. Commercial power inverters and converters supply 120 volt AC power from a 12 volt DC source such as a car battery or solar panel.

Check the equipment you want to power with 120 volt AC for its wattage rating. You will need a 12 volt DC to 120 volt AC converter rated to supply this amount of current (amps). Most 12 volt DC power lines in cars are fused at 10 to 15 amps, so you will not be able to generate more than 180 watts of power from these lines without blowing a fuse. If you connect to the battery itself, you can obtain more than 120 volt AC amperage.

Connect the inverter to the 12 volt DC source with the appropriate plug. If you are using a car battery, you can plug into the cigarette lighter or auxiliary power plug (if you have one) or you can connect the inverter directly to the battery poles. Make sure you observe the proper polarity.

Connect the inverter output to the equipment you want to power by plugging the equipment power line into the inverter, and then make sure the equipment is off before turning the inverter on. Turn on the equipment when the inverter indicates that power is present.


  • If you plan to power the inverter from a battery in a car while it is running, make all the electrical connections, then start the car, then start the inverter, then start the equipment. The inverter may not filter engine noise adequately from the incoming 12 volt DC power, so it may generate noise in your equipment.

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About the Author

Michael MacLeod has been a senior technical writer in California's Silicon Valley since 1976. He has written every kind of engineering and end-user documentation for a variety of computer hardware and software. He received an Associate of Arts in English from the College of San Mateo.

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