At the same time, the power cord also acts as a charger, similar to a cell phone charger - it powers up your 
on an ongoing basis. 
power supply is somewhat adaptable, therefore, making laptops portable - at least for a few hours at a time, that is. The newer models often have a battery that holds a charge for longer - five to seven hours, in some cases. Adding an additional laptop power supply - an external battery - can increase the time that you can spend away from an electric power source.
Some people recommend removing your laptop battery when you're at home or in the office, so that your laptop power supply source bypasses the 
when possible. However, shopping around to find exactly what you need - especially if your needs are unusual - is also worth your while.
