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I need Help about 12v - 240v inverter

  1. May 1, 2012 #1
    Hello, I have a question, I've googled to find the answer but I didn't find any.

    I have 12v 100amp battery, 12v-220v 300watt inverter and 220w 220v appliance.

    I want to run the 220w appliance on the 12v battery by using the inverter.

    My Question is: How long will it last until the battery is fully discharged?

    Please write the equation so it will help me in the future, Thank you.
  2. jcsd
  3. May 1, 2012 #2


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    Science Advisor

    That would be a 100 amp-hour battery.

    It would be useful to know the eficiency of the inverter, but make a guess and call it 70 %

    Power into the inverter from the battery = (100 % / 70 %) * 220 watts or 314 watts.

    Current into the inverter from the battery = 314 watts / 12 volts = 26 amps.

    The battery is 100 amp - hours so the time it would run is 100 amp-hours / 26 amps or 3.8 hours.

    However, I have assumed that the load is not inductive or capacitive which could make the result worse.
    What are you actually trying to do?
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