How long will a 11.1volt 5200 mah. battery last in laptop?

The runtime of a 11.1V, 5200mAh battery in a laptop depends on the laptop's power consumption. If the laptop consumes around 20 watts, for example, you can estimate the battery life using the formula: Battery life (hours) = (Battery capacity in watt-hours) / Power consumption in watts. In this case, the battery has approximately 57.72 watt-hours (11.1V * 5.2Ah), yielding about 2.89 hours of use. Actual runtime may vary based on usage and efficiency.