How much power does an inverter draw with no load connected?

A typical domestic power inverter can consume anywhere from 2 to 10 watts from the battery even when no load or appliance is connected provided it is switched on (idle).

In terms of the current draw, for a 12V inverter, is between 0.2 to 0.8A and 0.1 to 0.4A for a 24V inverter.

This no load power draw keeps the inverter’s internal electronics energized.

Inverter no load power draw vs current

Inverter manufacturers usually specify the no load current draw instead of no load power in the inverter’s electrical specifications.

To work out the inverter’s equivalent power consumption for a given no load current, multiply no load current by the inverter’s battery voltage.

For example, a 12V, 500W inverter with a no load current of 0.4 A, has a power consumption of 12 x 0.4 = 3 W.

To obtain the inverter’s no load current from the idle power consumption, divide the power consumption by the system voltage, in this case, 3W by 12V = 0.4 A.

Indicative no load power consumption (W) for selected inverter capacities (W)

No.Inverter ModelPower rating (W)No load power (W)No load current (Amps)
1Xantrex XPower300<2.4<0.2
2Xantrex XPower400<3.6<0.3
3Xantrex Prowatt SW600<7.2~0.6
4Xantrex Prowatt SW1000<9.6~0.8
5Xantrex Prowatt SW2000<9.6 ~0.8

Whereas this is for Xantrex inverters – an  inverter with similar wattage will likely consume about the same power depending on its efficiency,

Inverter no load power consumption and why it matters

A low no load power consumption reduces overall power wastage.

This power wastage adds up when the inverter is idle for long periods and is concerning considering that batteries have limited energy stored.

For example, an inverter with a no load power consumption of 10W connected to a 12V, 100 Ah battery uses up 20Ah (20%) of the battery’s capacity over 24 hours.

How to reduce inverter no load power consumption

To reduce an inverter’s no load power consumption:

# 1. Switch off the inverter when no appliance is connected. This disconnects the internal inverter circuit and reduces the no load power draw.

Some inverters have remote switches to switch on/off the inverter from several feet away.

This can be helpful when the inverter is installed several feet away from the appliances, for example in an RV.

# 2. If your inverter has an energy-saving mode sometimes called a search feature or eco mode make sure it is activated.

When the inverter detects loads 10W or below (depending on the inverter model), it switches to idle mode to reduce current draw to significantly – sometimes as low as 55 mA or less than 1W.

Do larger inverters draw more power?

Yes. Larger inverters generally consume more power compared to smaller rated inverters.

Take the Xantrex Prowatt SW 600W ‘s no load power consumption of about 7.2W (see table above). This is about 3 times more than XPower 300W’s 2.4W.

Select your inverter size such that its power rating is slightly more than the total combined power rating of loads connected to it.

Connecting too small a load to an inverter (compared to its power rating) reduces the overall efficiency of the inverter setup.

Inverters consume battery power even when no appliances are switched on. To reduce the no load power consumption, switch off the inverter or if it has an energy-saving mode, activate it.

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