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Old 02-29-2016, 11:50 AM   #1
omc
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Watts to amps calculator

It is always helpful aboard to know how to convert electric power in watts (W) to electric current in amps (A), here is an easy calculator :

Watts to amps (A) conversion calculator
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Old 02-29-2016, 11:11 PM   #2
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Just remember PIE or P = IE, Then re-arrange to find the missing term.

Power (watts) = Current(amps) x Volts
or
Current(amps) = Power(watts) / Volts
or
Volts = Power(watts) / Current(amps)
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Old 03-01-2016, 12:03 AM   #3
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VAW=Volt x Amps=Watts
Regular math after that, or see TG's version above.
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Old 03-01-2016, 05:41 AM   #4
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Quote:
Originally Posted by TG View Post
Just remember PIE or P = IE, Then re-arrange to find the missing term.

Power (watts) = Current(amps) x Volts
or
Current(amps) = Power(watts) / Volts
or
Volts = Power(watts) / Current(amps)
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Old 03-01-2016, 10:09 AM   #5
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I noticed that the calculator also solves 3 phase AC with the power factor of the load. Not quite as easy as the DC case!

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Old 03-01-2016, 10:23 AM   #6
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Maybe I missed it in the nice calculator, but - another complication to remember:

If you're figuring amp draw from batteries when using a 120V device through an inverter, add 10-15% to your amp calculations for inverter inefficiencies.
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Old 03-01-2016, 10:41 AM   #7
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Quote:
Originally Posted by RCook View Post
Maybe I missed it in the nice calculator, but - another complication to remember:

If you're figuring amp draw from batteries when using a 120V device through an inverter, add 10-15% to your amp calculations for inverter inefficiencies.
Excellent point. One good reason to have an amp meter and a battery monitor. It will vary with how much a load is on it. Most converters I am familiar with publish their efficiency as a spec. For instance my Magnum MS4024 was rated at 93.7% peak at 1400 watts. They publish a curve showing efficiency over various draws, in this case down to 85% at maximum wattage of 4000, with the drop off sharpening at 3000.
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Old 03-01-2016, 11:23 AM   #8
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I always tell boating-type people to remember the acronym WAVe - W = A x V.

Whichever acronym you choose, the math is all the same, and incredibly easy for anyone who was brought up before they invented calculators.

As for the rest, I suppose they're bound to use an app for that.
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