Should You Leave Your Laptop Plugged in All the Time?

LAPTOPS ARE OUR indispensable lifeline to the majesty that is the Internet. We use them to work and play from anywhere in the world. But if you're like most people, you probably keep yours plugged in when you're at work or home. Stop doing that.

In order to squeeze as much life out of your lithium-polymer battery, once your laptop hits 100 percent, unplug it. In fact, you should unplug it before that.

There are two main types of batteries used in laptops: lithium-ion and lithium-polymer. Although they are different technologies, they function in broadly the same way, generating power through the movement of electrons.

This constant flow is also needed to help keep the battery healthy.

For both types of batteries, the following statements are true (at least as far as modern laptops are concerned):

A battery cannot be overcharged. There's no danger of overcharging a battery if you leave it plugged in all the time. As soon as it hits 100 percent, it will cease charging and won't start again until the voltage falls below a certain level.

Fully discharging a battery will damage it. Allowing the battery to become completely empty for an extended period can put it into a deep discharge state. This can be fatal---you might never be able to charge it again.

The truth about lithium-based batteries is that they are inherently unstable. They begin to lose capacity from the moment they are produced, and numerous factors hasten their decline. These include:

Charge/discharge cycles. Every battery has a finite number of times it can be charged and discharged. Voltage level. The higher the charge level (measured in volts per cell), the shorter the battery's life. High temperature, over 30 degrees celsius. This can cause irreparable damage.

High temperatures, typically classified as being over 30 degrees Celsius, will shorten the life of a battery irrespective of any other factors. Simply leaving your laptop in your car on a summer afternoon is a bad idea.

When you combine the stress of high temperature with the stress of high voltage, the effects are even worse.