Fast charging is a convenient way to top up your phone’s battery, provided your device supports it and you have a charger capable of delivering the required power. But does this time saving negatively affect battery life?
Charging works in phases to protect the battery
Fast charging is not inherently harmful to your phone’s battery. Fast chargers cannot “overcharge” a battery since the smartphone will only request the power that the device can handle. This means you can safely use a USB charger that pumps more power than your device’s maximum charge rate.
A smartphone battery can only use fast charging for a limited time. This is because lithium-ion batteries charge in three phases: a slow “trickle charge”, a constant current state where the voltage increases over time, and a final constant voltage state where the current is slowly reduced to avoid overcharging and damage to the battery cell. .
Fast charging only works during constant current state, that’s why many smartphone manufacturers advertise a fast charging window, for example, “charge to 50% in 30 minutes” or similar. Once the last constant voltage phase has begun, charging resumes at standard rate.
Fast charging can generate more heat
The faster the power is stored in the lithium-ion cell, the more heat is generated. This means that a fast charge generates more heat than a standard “slow” charge. This could be a problem as excessive heat will degrade lithium-ion batteries. Fast charging can shorten battery life compared to using a standard charger.
Most studies of the heat generated by fast-charging lithium-ion cells focus on electric vehicle batteries, which are much larger than smartphone batteries. The results of these studies suggest that some fast charging methods degrade the cell at a much faster rate than standard charging.
Since extreme temperatures are the enemy of any lithium-ion battery, using your phone in very hot or cold environments or leaving your device in direct sunlight can also damage the battery.
To get the most out of your battery, reserve fast charging for times when you need to quickly recharge your smartphone. Use a standard charger at other times when you have free time.
Smartphone batteries are replaceable
Smartphone battery replacements are relatively affordable compared to the price of a new phone. Apple charges between $49 and $69 (depending on the device) for an out-of-warranty battery replacement that will restore your device to like-new battery performance.
Many Android devices have easily accessible, user-replaceable batteries, while others can be repaired by the manufacturer or a third party for a moderate fee. iPhones and Android devices can be serviced with a new battery by the user using parts and guides available from resources like iFixit.
Batteries will degrade over time even with ideal use. Understanding when it’s time to replace your battery (and how it might net you a performance boost) can be helpful.