There are many cost-saving arguments for buying used laptops. Even ones that are up to three years old can still pack a good deal of computing power. However, some of the money saved from not buying the item brand new needs to be set aside for secondary costs like buying a fresh battery or more working memory, advises German computer magazine c't in a recent review.
Whereas new batteries can sometimes run a computer for up to 10 hours, used ones might last only half as long or less as the storage unit loses capacity. The older the device, the harder it is to find a fresh replacement battery.
Since most devices have only a limited span as a market leader before a newer, faster product bumps them and their accessories from the front of the display shelf, replacement batteries will not be available forever.
It's very unlikely to find a freshly manufactured battery years after the release of a computer.