Inverter Question

Discussion in 'Homework Help' started by speedster239, Jul 3, 2010.

  1. speedster239

    Thread Starter New Member

    Nov 24, 2009
    If I have an inverter for my boat which allows me to produce 120v AC from 12v DC and I have a 120 watt lightbulb running after the power is inverted that means that 1 amp is flowing after the inversion. BUT, how much current is being drawn from the batteries themselves before the inversion?

    Based on what I know I'd say since 120watts power is necessary to operate the bulb that would mean 12 volts/120 watts = 12 amps. That means the bulb is drawing 12 amps from the batteries themselves before the inversion? Is this correct or is my thinking completely flawed?

    Thank you so much,
  2. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    I = P/E

    The problem is you need to know the efficiency of your inverter to determine the current drawn from the battery. Assuming a 80% efficiency means the battery is providing 150 W so you can enjoy that 120 W light. Then P/E or 150/12 = 12.5 amps.