When a phone stops charging, people assume the battery or the charging port is broken. Far more often it is something cheap and easy to fix. Work down this list in order.
1. Swap the cable, then the plug
Cables fail inside even when they look fine, especially near the ends. Try a different cable with a different plug. If the phone charges, you have found it.
Cheap chargers bought by the roadside often cannot supply enough power for modern phones, and some are unsafe. See choosing chargers and power banks.
2. Clean the charging port
Pocket fluff packs into the bottom of the port over months until the cable no longer goes all the way in. Shine a torch in and look.
- Switch the phone off.
- Use a wooden toothpick, not a pin or anything metal.
- Gently scrape along the bottom of the port and lift the fluff out. You will often be surprised how much comes out.
- A soft dry toothbrush helps loosen it. Do not use water or blow into it.
3. Try a different socket
This sounds obvious, but a socket or extension board can be faulty, and low voltage during unstable power supply makes charging very slow. If the charger works in another room, the problem is the wall.
4. Restart the phone
A software fault can stop charging. Restart, and for a stubborn case, charge the phone switched off for 30 minutes.
5. Check for a moisture warning
Samsung and other phones refuse to charge when they detect moisture in the port. Let it dry for a few hours; do not force it with a hair dryer. Wireless charging, if your phone has it, still works in the meantime.
Why it charges slowly
- The charger is a low-power one (5 watts). Fast charging needs a charger and cable that support it.
- You are using the phone heavily while it charges, especially games or video calls.
- The phone is hot. Phones slow charging down to protect the battery above about 35°C. Take the case off and keep it out of the sun.
- Charging from a laptop USB port is always slow.
When it really is the battery or port
Signs that need a technician:
- The battery percentage jumps around, or the phone dies at 20 to 30 percent.
- The back of the phone is lifting or the screen is being pushed out. This is a swollen battery. Stop charging it, keep it away from anything flammable, and get it replaced; do not press on it.
- The cable is loose and only charges at a certain angle, even after cleaning.
A charging port replacement is one of the cheaper phone repairs.