Somebody told you it ruins the battery. Somebody else said modern phones stop when they are full. Both sound plausible, only one is what the makers publish, and there is no need to lose sleep over it.
The manufacturers have answered this directly, and their answer is more relaxed than the advice circulating about it.
I went and read what they say, and the interesting part is not the yes or no. It is the setting they built afterwards anyway.
The direct answer, from a phone maker
One sentence settles the overcharging question, and Samsung says it outright on its overnight charging page.
"Your phone's battery will not be at risk of overcharging if you leave it plugged in overnight." At 100% the charger "only kicks in occasionally to top off the battery, maintaining it at 100%."
Samsung has a name for those: "These are called 'maintenance charges.'" The phone is not sitting there being force-fed all night. It tops up, stops, and waits.
The part the panic articles get half right
There is a real effect, and it is not the one people describe. Samsung states the cost of sitting full: "Keeping your battery at a full 100% charge for a long time can reduce its lifespan."
That is different from overcharging. Nothing is being overfilled. The battery is simply being held at its most stressful state.
Samsung is honest about the size of it. Unplugging at 100% is "technically recommended," but the company adds that "the actual benefit is quite minimal."
A maker saying the benefit of its own advice is minimal is worth noticing. Most pages on this subject do not mention that line.
The setting they built instead
Since the effect is real but small, the makers automated it. Samsung ships three protection modes, and Maximum is the strict one: "Your battery will stop charging when it reaches 80%."
In its own words, Basic means "whenever your battery is charged to 100%, charging will automatically stop until the battery level drops down to 95% before it starts charging again."
Adaptive is the one built for exactly this question. Samsung: "Your device will switch to 'Maximum' mode while you're asleep and back to 'Basic' mode before you wake up."
Turn Adaptive on and the question stops mattering. The phone spends the night at 80% and is full when you reach for it.
What Google does with the same problem
A different name, the same thinking. Documented by Google as Adaptive Charging, and aimed at long charges rather than short ones. It holds back and finishes late. You get 100% near the time you normally unplug, not at two in the morning.
Google also offers a limit at 80% for people who end most days with charge to spare. Both makers built the same answer. The effect is real. Neither thought you should manage it by hand.
What actually shortens a battery's life
Ours, and the overnight question is not near the top of it. Heat is the one that matters. A phone charging under a pillow or on a car dashboard in summer is doing far more damage than a full battery overnight.
Charge cycles count, and a full cycle is a full cycle whether you do it overnight or in three goes during the day. Fast charging generates heat. That is why some phones slow themselves when they warm up.
Take the case off if it charges hot. That single change beats any amount of unplugging at the right moment.
So what to actually do tonight
Three things, and none of them involve setting an alarm. Leave it plugged in. The maker of your phone says overcharging is not the risk.
Turn on the protection setting if your phone has one. Adaptive or its equivalent is free and needs no attention afterwards. Charge it on a hard surface, not under a pillow or in the bed. Heat is the real enemy.
And stop worrying about the percentage. The number worth watching is the wear figure, and on a laptop Windows will give you it.
When slow overnight charging is a different problem
Because a phone that is not full by your morning alarm is not a health question. A phone still at 60% after eight hours is a charging fault, not battery aging.
The usual causes are the cable, the adapter and the port. I would test them in that order. All three are cheap. A phone that charges then drops back overnight is running something. That is a background app question.
And a phone that will not charge at all is its own list. Android has a specific order worth working through.
**Status: this one rests on Samsung's published guidance on overnight charging and its battery protection modes, plus Google's charging documentation, all read 18 September 2026.
No battery was measured here, no charge was timed, and no figure in this article was produced by testing a phone.**
Does charging overnight damage the phone battery?
No. Samsung's wording is that your battery will not be at risk of overcharging if you leave it plugged in overnight, and that the charger only kicks in occasionally to maintain it at 100%.
There is a smaller separate effect from sitting at 100%, which is what the protection settings are for.
Should I unplug my phone at 100%?
Samsung calls it technically recommended, then says the actual benefit is quite minimal. If you want the benefit without the alarm clock, turn on the battery protection setting and let the phone do it.
What does the 80% charging limit actually do?
It stops charging at 80% so the battery spends less time at full. Samsung's Maximum mode does exactly that, and its Adaptive mode uses Maximum while you sleep then switches back before you wake up. Google offers a similar 80% limit.
What damages a phone battery the most?
Heat, by a distance. Charging under a pillow, in a hot car or in direct sun does more harm than any charging schedule. Charge cycles matter too, and both are bigger factors than whether you unplugged at the right moment.
The Short Version
- Samsung says a battery is not at risk of overcharging when left plugged in overnight.
- At 100% the charger only tops up occasionally, in what Samsung calls maintenance charges.
- Sitting at 100% for a long time does shorten lifespan, which is a different thing from overcharging.
- Samsung calls the benefit of unplugging at 100% quite minimal.
- Basic stops at 100% and resumes at 95%. Maximum stops at 80%.
- Adaptive uses Maximum while you sleep and Basic before you wake.
- Google built the same answer under the name Adaptive Charging, with an 80% limit as well.
- Heat does more damage than any of this. Charge it on a hard surface, not under a pillow.
Where to Next
Leave it plugged in tonight, because the company that made it says overcharging is not what happens.
Look for the battery protection setting and turn on the adaptive option, since it solves this without you thinking about it.
Move the phone off the bed and out of the pillow, which is the change that actually matters.
And if it is not full by morning, treat that as a charging fault rather than a battery that is wearing out.
If your phone offers a protection setting under a different name, say what your maker calls it in the comments. Those names vary more than they need to.
Isaac Smith is the founder and editor of PC Glance, a website that covers computers, laptops, and technology. He is a tech enthusiast and a computer geek who loves to share his insights and help his readers make smart choices when buying tech gadgets or laptops. He is always curious and updated about the latest tech trends.