While experts’ advice sometimes conflict, with proper care, your laptop’s battery should last you a few years; without it, it may quickly begin losing charge or need to be charged more frequently.
The confusion on this arises from the different care required for older, nickel-based batteries that lasted longest when completely drained and then completely charged. While it’s inevitable that you’ll occasionally use up all the charge or leave your laptop battery charging beyond reaching full capacity, there is a bit of finesse involved in getting the most out of your lithium battery.
First of all, don’t drain your battery level below 40 to 50% on a regular basis. A partial discharge is far less stressful on your battery, ultimately prolonging its life. This is for your regular charging activity. Once every month or so, however, you should use up every bit of battery life. Since most lithium batteries these days are “smart” ones, they are able to relay information about the remaining amount of charge. By completely draining the battery periodically, it recalibrates this system, making it more accurate in the long run.
Secondly, you should not regularly charge your laptop battery to full capacity. The longer your battery charges, the higher its temperature gets. This adversely affects your battery’s capacity to hold a charge.
Once that capacity is lost, it is gone forever. So, taking this all into account, the best way to prolong laptop battery life is to maintain a charge between 40 and 90% at all times, except for a complete drain monthly.