Inverter question

[Ntrain2k]

Just wanting to make sure I'm grasping the conversion of DC to AC power.

Not counting inverter effeciency.

140 watts@120VAC would be equal to 1400 watts@ 12V DC through an inverter.

And, that 1400 watts@12VDC would be 116.67 amps?

Thanks in advance.

[tanner0441]

Hi

140 Watts is 140 Watts.  Watts Divided by Amps 140 /12 = 11.6 A

thats an absolute reading there will be some small difference depending on the inverter efficiency.

VXA=W

W/A=V

W/V=A

Brian

[WineGuy]

You are confusing watts with amps.

The amps (for a given load) is ten times as much at 12 volts as it is at 120 volts.

Example:

120. watts at 120 volts is 1 amp.
     
120. watts at 12 volts is 10 amps.
     
     

watts is Volts times amps

The inverter is putting out 1 amp, because it is at 120 volts. The battery needs to supply 10 amps to the inverter because it is only at 12 volts. Power into the inverter is (almost) power out of the inverter.

The inverter just converts low volts DC to higher volts AC.

[Ntrain2k]

So I was correct in my figuring?

[Electron Pump]

  Something sounds a foul. My 8HP welder runs at 100amps. Around 4000 watts. The 116.xxx amps thing scares me.

  Man I may be wrong, lets see. Say the inverter it running at 1 amp at 12v. Thats 120 watts. The battery has to supply 10 amps to the inverter to produce the needed 1 amp. 10 amps at 12v is 120 watts. Is that right?

[Electron Pump]

  In the second paragraph I ment 1 amp at 120v ac. Sorry.

[Flux]

No you are a factor of 10 out.

140W is 1.16A at 120v. When you invert from 12v the power stays at 140W so it takes 11.6A from the 12v supply.

Two others have explained quite clearly that power is the product of volts and amps and is the same irrespective of voltage. Just divide power by voltage to get current .

Flux

[Ntrain2k]

Good to hear, thanks Everyone!