The battery life of a 12V 200Ah lithium battery depends on several factors, including the power consumption of the device, the charging and discharging efficiency of the battery, the self-discharge rate, temperature, etc. Therefore, it is difficult to give an exact battery life.
However, we can calculate it theoretically. The theoretical storage capacity of a 12V 200Ah lithium battery is 12V multiplied by 200Ah, which is equal to 2400Wh, which is 2.4 kWh. If you use this battery to supply a 200W appliance, it can theoretically divide 2400Wh by 200W, which equals 12 hours. Note, however, that this is an ideal calculation, and the actual usage time may be a little shorter than the theoretical time.
Also, if you have a 100W appliance, then this battery can theoretically work for 24 hours (2400Wh divided by 100W). But again, the actual usage time may be reduced due to a variety of factors.
If you want a more accurate estimate of battery life, you can consider using a dedicated online calculator and entering the capacity of the battery and the power consumption of the device to get an approximate result. At the same time, please also pay attention to the relevant safety regulations when using the battery to ensure the safety and stability of the use process.