If you have purchase any laptop few years back you may have noticed your
laptop isn't holding charges as long as it was new. Often you are
running around looking for your laptop charging cables when you are in the
middle of drafting an important document or just about to make that
important purchase online.
HP, Dell and Lenovo have document on their version of how to troubleshooting
this problem, see links below.
Rule of thumbs are, if you have laptop and it has been more than 3 years and
you use it daily. It often is the time to replace the battery.
Many laptops' battery can be replaced just by removing back cover's screws and
the cover. There are so many youtube videos about them. Just enter
Battery replacement + your laptop model number.