12vDC - 120vAC

How do you calculate how much current a 12vDC-120vAC converter uses on the 12volt side if you are drawing 300watts on the 120volt side?

It depends on the efficiency of the converter.

On the 12 V side, the power consumption will be 300W + X where X is the power consumed by the converter, ie. it is not 100 % efficient in doing the conversion.

If its efficiency was say 80 % then the power input would be 300/0.8 = 375W.

The current at the 12 V side is therefore 375/12 = 31 Amp.

Len

opps I got it totally wrong and thanks Lj for clearing it up

cheers Bryan