How quickly an inverter drains the battery depends on various factors, including the battery's capacity, the power of the inverter, the energy consumption of the connected devices, and the duration of use.

Most inverters have a specified efficiency percentage, which indicates how much energy is lost during the conversion process. The higher the efficiency of the inverter, the less energy is lost, and the longer the battery lasts.

Additionally, the energy consumption of the connected devices is an important factor. For example, if you use an inverter with a power of 1,000 watts and connect devices that consume a total of 500 watts, the battery will last longer than when the connected devices consume a total of 900 watts.

It is also important to consider the battery's capacity. A battery with a higher capacity can store more energy and last longer before it is depleted.

It is difficult to give an exact duration because this greatly depends on the specific circumstances. If you want to know how quickly a specific inverter drains the battery, it is advisable to consult the technical specifications of the inverter and possibly contact the manufacturer for more detailed information.