Many people think charging their smartphone’s battery overnight is harmful to its longevity, but there are much worse things they could be doing.
“In reality, there is a very limited chance of [overnight] charging impacting [a smartphone’s] battery life,” Cellucity owner Sean Joffe told MyBroadband.
Joffe said smartphones use lithium-based batteries with lifespans typically measured in charge cycles.
“Smartphones typically have a battery capacity of 300 to 500 charging cycles, so the phone battery lasts between two and three years depending on usage,” Joffe said.
Popular Mechanics explains that after about 1,000 charge-discharge cycles, lithium-based batteries can lose roughly 20% of their capacity.
All batteries will degrade over time, but some behaviours speed up their degradation.
According to a PC Mag report, overnight charging is not as harmful as many believe because modern smartphones generally stop charging once the battery is full.
Leaving a smartphone plugged in overnight will keep trickle charging the battery to full capacity whenever it discharges.
The heat that trickle generates has the most potential to damage the battery, not the charging itself.
If you must charge your smartphone overnight, the recommendation is to avoid fast and ultra-fast charging and opt for slow charging instead.
You should also not cover your device by putting it underneath your pillow.
While smartphones have measures to protect the battery from overcharging, the same cannot be said for excessive heat.
Extreme heat affects the internal chemistry of smartphone batteries, damaging them.
For this reason, Joffe recommends you do not leave your smartphone in direct sunlight for too long, as this can be particularly damaging and potentially even dangerous.
“High temperatures can degrade the ultimate battery life and be quite dangerous. If your battery does swell up, have it replaced immediately. Do not puncture it as it will probably catch fire,” Joffe said.
RELiON also advises against charging your smartphone in sub-zero temperatures, as it could permanently damage the battery.
Charging your device in freezing temperatures could create a permanent plating of metallic lithium on the battery anode.
Joffe said the highest likelihood of damaging your smartphone battery comes from using cheap, off-brand chargers.
“Not all chargers or even cables are equal — probably the most damage to smartphone batteries is caused by using cheaper chargers,” Joffe said.
While most users are worried about overcharging their devices, letting a lithium-ion battery discharge completely too often shouldn’t be overlooked.
Lithium-ion batteries perform best when they are only partially discharged. The consensus suggests keeping your battery between 30% and 90%.
For example, Samsung’s “protect battery” feature limits the maximum charge to 85% on the company’s flagship devices when users enable it.
Joffe also mentioned that using your smartphone while charging does not have any significant deteriorating effect.
“It is not harmful to the device in any way to use it while charging. However, it may cause excessive heat build-up,” Joffe said.
Samsung also states on its support page that you can use your phone while charging.
“When you use your phone while charging, the battery is charging at a slower rate than normal to allow enough power for the ongoing usage,” Samsung says.