Many customers ask us how much laptop backup I will get with Energy Intelligence Laptop Power Bank. We give a range of 4-8 hours for the 25,000mAH unit, not because we don’t want to be precise, but because we cannot be precise because power consumption varies with a wide range of laptop configurations, peripherals connected, graphic cards, power settings and usage patterns. For example, did you know that even with WiFi router farther away by 25 ft \ power consumption of your wifi connected devices will increase. This is because the WiFi transceiver in the device will be continuously scanning the network and for longer distances will be re-transmitting more.
https://energyintelligence.in/blogs/news/backup-estimation