Off-Grid Solar Calculators

Inverters and charge controllers

Inverter Idle Draw Battery Drain

Many 2000 W inverters idle at 15–25 W. Left on for a ten-hour night that is 150–250 Wh — roughly what a laptop uses in a day. Switch the inverter off, use a DC load, or pick a unit with a low search/idle mode.

Inputs

Units
W
h

System voltage of the battery or series string.

Usable fraction of rated capacity.

Terms of Service

Results

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Engineering methodology

Energy wasted = idle watts × hours (Wh = P × t). Equivalent battery amp-hours = watt-hours ÷ (voltage × DoD), from Wh = Ah × V. DoD converts wasted energy into the rated capacity you would need just to cover idle. Measure idle at the DC input if you can.

Frequently asked questions

How much battery does a 20 W inverter idle use overnight?

20 W × 10 h = 200 Wh. On a 12 V bank about 16.7 Ah leave the battery; at 95% LiFePO4 DoD, covering that takes about 17.5 Ah of rated capacity—before any real AC load.

Does search or power-save mode change idle draw?

Yes. Many inverters draw far less in search mode than at normal idle, then wake when a load appears. Enter the mode you actually leave on overnight. Temperature and DC voltage also move idle watts.

Should I leave the inverter on 24/7 in a van?

Only if you need instant AC. Otherwise switch it off or use native 12 V loads. Idle can exceed a laptop’s daily energy.

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