An iPhone Duo not charging, or charging slowly, often has a cause in the cable, the adapter, the port or the temperature. Apple rates the phone at up to 50 percent charge in around 20 minutes with fast wired charging, so charging that falls well short of that is worth testing step by step.
Start with a wall outlet, since a computer port or a loose power strip can charge slowly. Test the phone after each step below so you know which one helped.
An iPhone Duo Not Charging Starts With the Cable, Adapter and Outlet
- Plug the iPhone Duo into a wall outlet and check that the cable, adapter and outlet all fit firmly, then try another outlet if you can.
- Restart the phone, then try again.
- Check the cable and adapter for damage such as a broken cable or bent prongs, and do not use damaged accessories.
- Look into the USB-C port on the bottom for debris, remove it, and push the cable in firmly.
- Let the iPhone Duo charge for half an hour before judging the result.
If the screen stays black or only shows a battery icon after that, force restart the phone and let it charge for another half hour. If it still will not charge or power on, you might need service.
Fast Charging Needs a 60W-Capable Cable and a USB PD Adapter
Apple tested the 50 percent in 20 minutes figure with the 40W Dynamic Power Adapter and a USB-C cable. Wired fast charging works with a 60W-capable or higher USB-C cable and a USB PD power adapter, so a cable or adapter that falls short of that can leave the iPhone Duo charging slower than the headline number.
Charge time also varies with the adapter, settings, usage and environment, so a phone that is in use or warm takes longer than the figure suggests. A USB PD adapter and a 60W-capable cable are what to look for when you shop for chargers for iPhone Duo.
Charging That Stops at 80 Percent Is Often a Setting or Heat
Optimized Battery Charging pauses past 80 percent when the phone expects a long session, such as overnight. A warm battery can also limit charging above 80 percent, and a Charge Limit you set earlier can stop charging at a chosen level.
If the phone feels warm, move the phone and charger to a cooler place and charging resumes when the temperature drops. If you want a full charge, change the Charge Limit.
An Unsupported Accessory Alert Points to the Port or the Charger
An alert that a charging accessory is not supported or certified often means a dirty or damaged port, a damaged accessory or a charger not designed to charge phones. Connect the iPhone Duo straight to the charger with nothing in between, clean the port, restart the phone, try a different cable or charger and install the latest iOS.
