Is A Bigger Inverter Better

What does an inverter do?

When you leave home and need to run some equipment powered by power, but your RV or boat is not connected to city power, now you need the inverter.

There are three main types of inverters: Compact or light, heavy and inverter. 
Compact or lightweight inverters can usually be plugged into 12 volt cigarette port in cars, recreational vehicles or ships. The rated power of compact or light inverters is usually as high as about 75 to 300 watts. Due to cost, modified sine wave inverters are usually chosen - it can connect to most load with the resistive load. Please remember that only the inverter with the rated power of 180W should be plugged into the accessory socket, otherwise there will be a risk of exceeding the rated current of the fuse.

So, is the bigger inverter better for usage?

Sometimes, the bigger inverter better. What we really need to know is what percentage of the power input from the battery to the inverter is output from the other side as AC power. To make this calculation more difficult, the efficiency of the inverter varies with the output load on it. If a small load is applied to the inverter, the efficiency may be only about 50%. However, when the load is increased to the maximum continuous load specified by the inverter, the efficiency will be improved to about 90%.

When a 2000 watt inverter is connected and turned on, it can draw about 20 watts of power from the battery without plugging anything into the output. This is the comsuption for the operation of the inverter itself... for battery monitoring circuit, alarm circuit, and perhaps a small fan. Now, when we connect with a small AC load... like 20 watts fan. The total load of the battery is now 40 watts (the inverter is 20 watts, the load is 20 watts), so slightly calculate that the efficiency of 40 watts input – 20 watts output is 50%.

Now, let us look again with a 150 watt small inverter, it will be connected to the battery without load, and it will take about 5 watts to run the inverter. Now, if we connect to the same 20 watt load, the inverter has 5 watts, the load has 20 watts, and the total load of the battery is 25 watts. Therefore, 25 watt input and 20 watt output make our efficiency about 80%.
In fact, this means that by choosing to use a 150 watt inverter instead of a 2000 watt inverter, you can run a 20 watt device on the same battery for longer.

So size is important. But bigger is not always better. It is very important to match the inverter size with the load size to maximize the running time of the battery.