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.
Order the correct battery for your laptop. The most reliable way to order a new laptop battery is to purchase it directly from your laptop manufacturer's website. Dell, Gateway, HP and Compaq all give users the ability to order replacement parts online for the exact computer model they have at home. This not only guarantees that you get the right type of battery, it also guarantees that the battery is a quality replacement part that you can feel confident about using in your computer.
Turn off your laptop computer when it is time to replace the battery.
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.
Remove the battery compartment cover from the laptop. Sometimes, the laptop battery is actually part of the compartment cover. On other models, the battery is located underneath the cover in a specialized compartment.
Replace the battery with the brand new battery you purchased. When installing the new battery, make sure you put it in correctly. It should go in exactly the same way as the old battery.
Close the battery compartment and re-lock it to prevent the battery from falling out.
Plug the laptop into an electrical outlet with the AC adapter that came with your computer. Allow the laptop to charge fully before using the battery for the first time. When the battery charging icon goes off, the charge is complete.