Laptop Battery run-time is difficult to determine. Actual laptop battery run-time depends upon the power demands made by the laptop's components. The monitor, the hard drive and other accessories result in extra drain upon the battery, effectively reducing its run-time.

The total run- time of the battery is also dependent upon the design of the laptop and all hardware plugged into the USB ports. Generally, a new BatteryFuel battery will run at least as long (and usually longer) as your old battery did when it was new. Laptops and other small electronic devices share smaller and lighter batteries and are rated by their Volts and Ampers or Miliamperes (1 Ampere or Ah is equivalent to 1000 Milliampere or mAh). To learn the runtime of a battery or its Watt-Hours, the Volts and Amps are multiplied by one another. Generally, the higher the volts the longer the Watt-Hours, but this can still vary depending on the Amps. To figure your battery's runtime, consider the formula below.11.1 Volts, 6600 mAh (6.6 Amperes)11.1 x 6.6 = 73.26 Watt-HoursThe 11.1 volt 6600 mAh laptop battery can power approximately 73.26 watts for one hour.

Now to estimate how long this battery will last in your laptop takes another configuration of dividing the 73.26 Watt-Hours by your laptop's watts. Your laptop's watts can normally be found in your manual. If your laptop uses 21.2 watts per hour, your laptop will power for 3.46 hours. (73.26 battery watts/21.2 laptop watts = 3.46 hours of estimated runtime). Keep in mind this is an estimated time and will vary depending on the components running on the laptop and any hardware plugged into the laptop.

You can find your laptop's watt hour usage in the user or specification's manual. Some laptop manuals will give more than one watt hour specification based on running the already installed OS by itself and or with one other program open as in the laptop's word processor. This watt information does not include the use of additionally installed programs, software and hardware. Once you open up other programs and start adding pheriphials, the run time will be reduced. Also, WiFi, Gaming and Video Streaming will eat up your battery power very fast and the laptop's watt hour use does not include these activities.