Month: April 2023

Charging overnight or in a cradle during the day is a very common habit, but it’s not recommended for several reasons (the old “overcharging” myth isn’t one of them). First, continuous trickle charging of a full battery can cause plating of the metallic lithium, which reduces stability in the long term and can, in rare cases, lead to system-wide malfunctions and reboots. Secondly, as we just mentioned above, it leaves the battery at a higher stress voltage when at 100%. Third, and most important, it creates excess heat caused by wasted power dissipation.

Notably, operating at a low voltage is good for a battery’s lifespan, increasing the number of available charging cycles before you’ll start to see a significant reduction in capacity. Roughly speaking, every 0.1V decrease in cell voltage doubles the cycle life, according to Battery University. Therefore, charging up your phone in that 30% to 80% range keeps the voltage lower and might slightly prolong the battery’s lifespan.

One particularly persistent battery myth is that you need to occasionally fully discharge and recharge to erase “battery memory.” This couldn’t be more wrong for lithium-ion batteries. It’s a leftover myth from lead-acid cells, and it’s pretty undesirable to charge your modern smartphone in this way.

Partial charging is just fine for lithium-ion batteries and can have some positive benefits for cell longevity. To understand why it’s important to appreciate how a battery charges. Li-ion batteries draw constant current and operate at a lower voltage when closer to empty. This voltage gradually increases as the cell charges up, leveling off at around a 70% charge before the current begins to fall until the capacity is full.