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eric1514's avatar
eric1514
Explorer
Jun 15, 2016

Do the math for me...

...and then tell me how you did it.

I have an appliance that is rated 130 watts at 110 volts (house current). How many amps per hour will this appliance draw from a 12 volt battery?

TIA
Eric
  • red31's avatar
    red31
    Explorer
    Jun 15, 2016
    130.000 watts / 12.0000 volts yields amps, you do the math.
    divide by .8 or .9 for inverter effiency
  • 2oldman's avatar
    2oldman
    Explorer II
    Jun 15, 2016
    130w /110 = 1.18 amps (Rule: Watts= amps x volts)

    Battery draw at 12v is approx. 10x what the 110v side draws, therefore, 10x 1.18=11.8 amps. (Rule: watts are conserved. Voltage is 1/10 of 120, so amps must be 10x)

    And it's not "amps per hour", it's just amps. If you ran it for one hour, that's 11.8 amp-hours.

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