Laptop batteries only last for about one to two years before they need to be replaced. If you are a Windows 7 user, your computer will notify you when it’s time to replace the battery. Otherwise, you’ll begin to notice the length of each charge becoming shorter over time — a sign that the battery is getting weaker and is unable to charge fully. When it’s time to replace the battery in your laptop, it’s crucial to the health of your computer that you use the correct type of battery for your laptop type.
Determine the precise kind of battery you need for your laptop. The easiest way to do this is to open the battery compartment on the underside of your computer and remove the old battery that needs to be replaced. On the battery, you'll find information on the battery's make and model number. Alternatively, you can consult your laptop's user manual or the support section of the manufacturer's website for information on battery replacements.
Flip over your laptop so the underside is facing upwards. If there is a switch for locking and unlocking the battery compartment, switch it to the unlocked position now.
Close the battery compartment and re-lock it to prevent the battery from falling out.