Portable batteries mainly provide electricity for portable and cordless devices. A more common definition is that it also includes driving a Subtyping under a large type (possibly operated by the main group), such as laptop. The Subtyping of the above model may be the clock or spare battery in the computer. Larger models of batteries, such as those weighing 4 kilograms or more, are not considered portable batteries. The typical portable battery nowadays is about a few hundred grams.