How Many Amps Does a 4,000 Watt Inverter Draw?

Answer
370 A at 12 V (full load)

Battery amps = watts ÷ (battery volts × inverter efficiency). At full load a 4,000 W inverter draws 370 A at 12 V, 185 A at 24 V or 93 A at 48 V (90% efficiency).

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PF
1.0 for heaters and lights; 0.8–0.9 for motors.
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How we calculated this

    For estimating and educational purposes only. Results are approximate and are not a substitute for a licensed professional, the manufacturer's instructions or your local code. Disclaimer

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    4,000 W inverter: current, fuse and cable

    BatteryFull-load currentFuse (125%)Copper cable (75 °C)
    12 V370 A500 A> 500 kcmil
    24 V185 A250 A250 kcmil
    48 V93 A125 A1 AWG

    The calculator above uses the input power: 4,000 W ÷ 0.9 = 4,444 W. Keep battery cables short (under 10 ft) or size up for voltage drop. Follow the inverter manual for fuse and cable sizes.

    Frequently asked questions

    How long will a 100Ah battery run a 4,000 W inverter?

    About 15 minutes at full load on a 12 V LiFePO4 battery.

    Should a 4,000 W inverter be 12 V or 24 V?

    24 V or 48 V halves or quarters the current, allowing thinner cables. Above about 2,000 W, 24 V or 48 V is recommended.

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