The industry-standard smartphone battery holds a charge of 1,440 mAh (approximately 5.45 watt-hours). While this is a generous amount of energy, though, it’s rarely enough to make a phone go through even just one whole day without recharging. This has led the burgeoning portable charger market to fill the gap between end-of-day charges.
The flip side of this development, however, is that incessant charging can and will shorten a battery’s lifespan, as uncovered by several studies. In particular, frequently going from no charge to full charge has drastic effects on the longevity of a battery, as these power packs are designed with a limited number of charge cycles (that is, the number of times that they can go from 0% to 100% charge). In fact, in some devices, fully discharging and then charging can even activate failsafes that would permanently disable the battery.