@kennedyhallmark,Kennedy, This is directly from Dell official site. All rechargeable batteries wear out with time and usage. As time and cumulative use increase, the performance will degrade. For the typical user, noticeable reduction in run time generally will be observed after 18 to 24 months. For a power user, reduction in run time generally may be experienced prior to 18 months. We recommend buying a new Dell laptop battery when the run time does not meet your needs. See links below for more info. Good luck. I hope this helped you out, if so let me know by pressing the helpful button.
http://www.dell.com/content/topics/global.aspx/batteries_sitelet/en/batteries_faq?c=us&l=en&cs=19#faq1
https://www.howtogeek.com/172362/how-to-know-when-its-time-to-replace-your-laptops-battery/