Some of the basic things we know are bad for batteries include extreme temperatures (hot or cold), overcharging, and complete discharging.
Thankfully, all smartphones today, are built to protect the battery automatically. For instance, your phone will shut down before the battery is completely depleted, and it won’t allow it to overcharge either. But there are still some things that can help prevent the battery from dying prematurely.
There are multiple ways a lithium-ion battery can age. First of all, Lithium-ion batteries have a finite number of charge “cycles”. In other words, how many times the battery can be fully charged and fully drained. Manufacturers usually will say batteries have between 300 and 500 cycles. The depth of the discharge matters as well, so it’s best to charge the battery as often as possible between uses. A partial discharge is fine for lithium-ion, there is no ‘memory’ and the battery does not need to be fully discharged periodically.
Heat plays a role, too. If a battery is kept in excessive heat (over 86 degrees) and in a full state of charge, that will diminish its overall capacity at a faster rate than discharge cycles.
Generally speaking, the best thing to do is keep your laptop or phone plugged in whenever possible in a cool environment. If you’re interested in battery longevity, it’s also best to avoid using fast-chargers.
Lastly, another great thing I have done since 2002 is to charge your battery for 12 hours right after you take it out of the box. You can still turn it on, activate it, program it,etc while it’s charging, but leave it on the charger for 12 hours. Every time I have done this, my battery life would lasts longer than most of my family, friends, and co-worker’s smart phones. However, when I did the opposite and turned my phone on right after taking it out the box, the battery wasn’t worth a damn during the period I owned it.