The practice of limiting smartphone charging to 80% to extend battery life may lead to significant compromises for users. While this feature is included in many new Android and iPhone models, it effectively reduces the battery's maximum capacity from the outset. Many manufacturers offer this option to prevent overcharging, but it results in users losing a fifth of their battery's capacity immediately.
Optimal performance for lithium-ion batteries occurs within a 20% to 80% charge range. Keeping a phone only partially charged can prevent the accelerated degradation associated with high voltage and heat. However, this practice means that a new phone's battery can exhibit the same capacity as a much older device, potentially losing about 4% of its capacity each year.
While users might appreciate the protection from overcharging, the trade-off is significant, as they could end up with only 60% of usable battery capacity if they also avoid letting the charge drop too low. Ultimately, despite the intention to prolong battery lifespan, limiting charging may not provide the anticipated benefits.