300W power supply with 110VAC input, and 12VDC output, what would be the max safe amperage you could draw?

I understand the "electrical triangle" I.E.... watts\volts=amps etc. but in this situation would you use the voltage from the ac or dc to calculate the amperage? I.E... 12x=300, Or maybe 110x=300.? (where x = amperage)

4 Answers

Relevance
  • 1 decade ago
    Favorite Answer

    If the 300 watts is ac input power to the power supply then the maximum output current you could safely draw from the power supply would be (300w/12V) times the efficiency rating of the power supply. The efficiency rating is always less than one.

    If the 300 watts is DC output power from the power supply then the maximum output current you could safely draw from the power supply would be the full 300w/12V=25 amps.

    • Login to reply the answers
  • 1 decade ago

    If it is truly 300 watts, then the output will handle 300/12 or 25 amps.

    The input will see 300/120 or 2.5 amps.

    Of course losses will change those numbers, as will marketeers sometimes fanciful numbers. In other words, I wouldn't count on more than 20 amps out.

    .

    • Login to reply the answers
  • 1 decade ago

    Watts = Amps * Voltage

    Amps = Watts / Voltage

    300/12=25Amps

    If you count in resistance and such, you should not try to draw more than 23 or 24 amps. bear in mind that you will also need to use wires rated for that high of amperage.

    • Login to reply the answers
  • Anonymous
    1 decade ago

    300/120=2.5amps

    • Login to reply the answers
Still have questions? Get your answers by asking now.