How long your laptop battery will keep your computer up depends on certain criteria. It may not be easy to determine. How long, depends on the laptop model that you have and the battery make. Some laptops can run for eight (8) hours or more on their battery alone, while others may last less than two (2) hours before they need to be recharged. You should contact your owners manual or manufacturer's website of your laptop brand. There you should be able to get an estimated run time. Also remember that the size of the screen, the power of your processor (dual or duo core and the i specs will consume powers differently), your hard ware and applications you run (DVD, CD/DVD-Burning, office, third party softwares, games and external hardwares plugged in at different periods) are all determinants. Eventually the pc will run out of power and you are left with the only option of recharging. Recharge the battery. Laptop batteries are rechargeable, simply plug it in to your AC powe...