If it stops at 80 percent
That is a setting, not a fault. Optimised Battery Charging holds the charge at 80% overnight and finishes before you usually unplug; newer models also have an 80% Limit that stops there every time. Both are in Settings → Battery → Charging. Our 80% limit guide explains when each one applies.
Charging that pauses with a note about temperature is the same kind of protection. Let the phone cool and it continues on its own.
Swap the cable, then the adapter
Try a different cable and a different power adapter, one at a time. Cables fail inside the sheath near the plug long before they look damaged. A computer's USB port charges far more slowly than a wall adapter, and some do not supply enough to charge a phone that is in use at all.
An Accessory may not be supported message means the phone has refused the cable or adapter — usually an uncertified or damaged one. Try an Apple or MFi-certified cable.
Clean the port
Pocket lint packs into the bottom of the charging port until the plug no longer seats fully. Shine a light in: if you see fluff, ease it out with a wooden or plastic toothpick. Never use anything metal, and never use compressed air, which can push debris deeper. A plug that clicks in more firmly afterwards is the sign it worked.
If the phone says liquid has been detected in the port, unplug it and let it dry for at least half an hour, port facing down. Charging wet risks corroding the pins.
If the battery is completely flat
A fully drained iPhone can show nothing for several minutes after it is plugged in, and the empty-battery screen for up to half an hour. Leave it connected to a wall adapter for thirty minutes before deciding it is not charging.
If it still shows nothing, force restart it while it is plugged in. A phone that was frozen rather than flat often comes back this way.
Wireless and MagSafe
Wireless charging needs the coil in the phone centred on the coil in the pad. Thick cases, cards and metal plates in the way stop it entirely. If wireless fails but a cable works, the pad, its adapter or alignment is the problem, not the phone.
Check the battery and update iOS
Settings → Battery → Battery Health shows whether the battery needs service. A worn battery charges unevenly and loses charge quickly, which can look like a charging fault. See how to check battery health.
Charging bugs in iOS are uncommon but real; if the problem started right after an update, the next update is worth installing — our update guide covers it.
When it is hardware
If several known-good cables and adapters fail, the port is clean, and the phone does not charge wirelessly either, the charging port, its connector or the battery has failed. A phone that charges only when the cable is held at an angle has a worn port. Both are repairs rather than settings; when to replace an iPhone battery covers what a battery service involves.
Frequently Asked Questions
Why won't my iPhone charge past 80%?
Optimised Battery Charging or the 80% Limit is on. Both are in Settings → Battery → Charging, and both exist to slow battery wear.
How do I clean my iPhone charging port?
Ease out lint with a wooden or plastic toothpick, with the phone switched off. Never use metal or compressed air.
Why does my iPhone say accessory not supported?
The cable or adapter is uncertified, damaged or dirty. Try an Apple or MFi-certified cable and clean the port.
My iPhone is dead and won't charge. What do I do?
Leave it on a wall adapter for thirty minutes, then force restart it while it is still plugged in.