8000 watt power inverters How is the battery is equipped with a suitable inverter?

If the specifications of the battery is 12 V, 50 Ah, we multiply by 12 volt 50 A, the output power of the battery obtained is 600 watts. If the inverter efficiency is 90%, then 90% then we Off grid inverter‍ multiply 600 watts, 540 watts obtained. This means that you can push a piece of battery output power up to 540 watts inverter. Of course, you can also take the "one step" type of procurement method, which is to present its own regardless of the specifications of the car with the battery, and buy a power output of 800 watt inverter. Then, the first piece of the battery within the allowable range of immediate use, such as the future for a greater use of the car before full power. Finally, do not ask for power inverters, for example, 100 watts is enough, then you can buy a small power inverter. Moreover, when determining the power of the inverter, there is an important principle that when using an inverter, not long-term operation at full load, which would significantly shorten the life of the inverter while the inverter failure rate is significantly rise. We strongly recommend that users, it is best to 12v pure sine wave inverter‍ use an inverter in not more than 85% of the rated power of the state.