“You need to fully drain your phone battery before recharging it to extend its lifespan.”

The idea that you must completely deplete your phone's battery before plugging it in for a recharge is a persistent piece of advice, but it's one that belongs firmly in the past. This misconception originates from the era of older battery technologies, specifically nickel-cadmium (NiCad) batteries. These batteries were notorious for something called the "memory effect," where they would "remember" their last partial discharge point and effectively reduce their usable capacity if not fully drained periodically.

However, the vast majority of modern smartphones, laptops, and other portable electronics use lithium-ion (Li-ion) batteries. Unlike their predecessors, Li-ion batteries do not suffer from the memory effect. In fact, the opposite is true: regularly running a Li-ion battery down to zero can actually be detrimental to its long-term health. Deep discharges put more stress on the battery's internal components, leading to increased wear and a faster degradation of its overall capacity.

Despite the widespread adoption of Li-ion technology, the old habit of fully draining batteries has proven remarkably sticky. This is largely due to the longevity of the initial advice and the tendency for such tips to be passed down without critical re-evaluation as technology evolves. For optimal lifespan, it's generally recommended to keep Li-ion batteries partially charged, ideally between 20% and 80%, and to avoid both complete discharge and prolonged periods at 100% charge. This approach helps to minimize stress on the battery, ensuring it performs well for longer.