You set your alarm, notice your phone is down to 23 per cent battery, plug it in beside the bed and go to sleep.
asserted
phone → set → sleep
By the morning, it's been connected to the charger for some seven to eight hours — much longer than it needed to reach 100 per cent, especially if it's on a fast charger.
asserted
it → connect → charger
You may have a vague recollection this could be bad for your phone's battery.
uncertain
this → have → battery
The chemistry that makes lithium-ion batteries rechargeable has a limited shelf life, and it's shortened by repeated charge–discharge cycles.
asserted
it → make → cycles
In the past, the advice has been simple: don't leave your phone charging overnight and avoid bringing the battery up to 100 per cent to preserve its life span, ideally keeping it between 20 and 80 per cent.
asserted
advice → leave → cent
In principle, that advice is still sound because the fundamental chemistry of the battery inside your phone hasn't changed.
asserted
chemistry → change → phone
Regularly draining it to 0 per cent and then filling it up to 100 per cent will shorten its life span.
asserted
draining → drain → span
However, modern phones have improved battery health management and charging controls.
asserted
phones → improve → management
As a result, the answer to whether it's okay to leave your phone plugged in overnight has become more nuanced in recent years.
asserted
it → leave → years
Better charging controls
Rather than simply telling people not to charge overnight, modern phones can increasingly manage what happens to the battery during those night-time hours.
asserted
what → tell → hours
Apple has offered optimised battery charging since 2019.
asserted
Apple → offer → 2019
This feature learns a user's daily charging routine and delays charging beyond a certain percentage when the phone is expected to remain connected for an extended period.
Samsung and Google Pixel phones both offer a similar feature.
asserted
phones → learn → feature
Pixel phones have "adaptive charging" which also learns charging habits and slows charging overnight, aiming to reach 100 per cent shortly before you normally unplug the phone.
asserted
you → have → phone
Samsung phones have "sleep time protection" which stops charging at about 80 per cent while you sleep and adjusts charging to reach 100 per cent just before you wake.
asserted
you → have → cent
With the new iPhone 17, Apple has also introduced adaptive power mode, which learns typical battery consumption and anticipates when the user might run low, then adjusts power use to help the battery last through the day.
uncertain
battery → introduce → day
Setting charging limits
So what about charging only to 80 per cent? Reducing time spent at a high state of charge can help manage battery wear.
asserted
Reducing → set → wear
But manufacturers themselves no longer treat 80 per cent as the only choice.
asserted
manufacturers → treat → choice
Samsung allows users of their most recent phones to set up battery protection that caps charging at a percentage of their choice: 80 per cent, 85 per cent, 90 per cent or 95 per cent.
asserted
that → allow → choice
Apple's iPhone 15 and later have a similar feature, allowing users to choose between 80 and 100 per cent in 5 per cent increments.
asserted
users → have → increments
The phone can even recommend a particular limit based on the user's charging habits.
asserted
phone → recommend → habits
Instead of using adaptive charging, Google Pixel 6a and later devices can simply be set to a limit of 80 per cent, an option that's ideal for people who usually finish their day with some charge remaining.
asserted
charge → use → day
Ultimately, not charging your phone fully is a trade-off between reducing battery wear over the longer term and having more charge available day-to-day.
asserted
charge → charge → day
If 80 per cent comfortably gets you through the day, a lower limit will make sense.
asserted
limit → get → sense
If you're travelling or facing a long day away from a charger, you may want to use more of the battery's capacity.
uncertain
you → travel → capacity
Even if you do choose a lower charging limit, your phone may occasionally charge itself to 100 per cent so the device's battery readings remain correct.
uncertain
readings → choose → cent
Whatever you do, avoid heat
While all these new charging features can prolong the life of the battery, they don't really address another important factor: heat.
asserted
they → do → factor
The chemicals in lithium-ion batteries are sensitive to high temperatures and will degrade over time if stored in hot conditions, especially if they're also being charged at the same time.
asserted
they → degrade → time
Phones themselves increasingly respond to heat too, with charging limitations kicking in when the device detects high temperatures.
asserted
device → respond → temperatures
The general advice here hasn't changed.
asserted
advice → change → ?
If charging at bedtime, make sure you're not tucking your phone under a pillow or other bedding which could trap heat and risk overheating the device.
uncertain
which → charge → device
So, can you charge your phone overnight?
asserted
you → charge → phone
For most people using a modern smartphone, the answer is yes.
asserted
answer → use → smartphone
The phone manages charging automatically, and you don't need to wake in the middle of the night to unplug your phone at exactly 80 per cent.
asserted
you → manage → cent
Instead, check what your phone offers and use optimised, adaptive or sleep-aware charging if it suits your routine.
asserted
it → check → routine
Consider a lower charge limit if you don't need 100 per cent every day.
asserted
you → consider → cent
Even though phone batteries still aren't immune to aging, we now have more options to try and prolong their life with smart charging features — so it's a good idea to check your settings and let the technology do some of the work.
asserted
technology → have → work
This piece first appeared on The Conversation.
asserted
piece → appear → Conversation
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