No, unless your smartphone runs on the old Nickel Metal Hydride batteries of yore. Draining Nickel-based batteries were done in order for these batteries to “remember their full potential”. Lithium-Ion batteries need to be treated differently from their predecessors.
If you want to prolong your smartphone’s battery life, it is best to keep the battery charged at 50% of its capacity most of the time, if possible. Draining the battery from 100% full to completely empty won’t help and may in fact, do a little damage if this is done too often. Draining the battery once a month is recommended but not more than that.
However, it is also not advisable to keep your battery charging at all times because the battery can overheat. Fortunately, most chargers cut your phone off and stop the charging process once the battery is full. Once full, remove the phone from the charger. Keeping the phone connected to the charger when the battery is full is also likely to cause minor degradation.
Lithium-ion batteries are a tricky lot because these kinds of batteries do not like being 100% full either. If you want to optimise your phone’s battery life, when your battery reaches 40% charge it up to reach the 80% range.
Caring for your smartphone is more than getting fancy casing and phone covers – it includes caring for the battery as well. If you take good care of your smartphone (both the unit and the battery), your phone will serve you well for at least 3 to 5 years.