How to Fix iPhone Not Charging or Charging Slowly

Plugging in your iPhone at the end of a long day only to wake up to a dead battery is incredibly stressful. When an iPhone refuses to charge, or charges painfully slowly, users often fear they need an expensive battery replacement or a logic board repair. However, in the vast majority of cases, the issue is caused by a simple physical obstruction or a misunderstood iOS software feature.

Before you rush to an Apple Store, follow this advanced troubleshooting guide to correctly diagnose and fix an iPhone that is not charging, stuck at a certain percentage, or rejecting your charging cable.

1. Understand “Optimized Battery Charging”

If your iPhone charges perfectly fine but completely stops when the battery reaches 80%, your device is likely not broken at all. This is a built-in iOS feature called Optimized Battery Charging.

Lithium-ion batteries degrade faster when they are held at 100% capacity for extended periods. To prevent this, iOS learns your daily charging routine (for example, if you leave it plugged in overnight). It will rapidly charge to 80%, stop charging, and then wait to finish the final 20% right before you normally wake up.

How to Test and Override This Feature:

1. Open the Settings app on your iPhone.
2. Navigate to Battery > Battery Health & Charging.
3. Look for the Optimized Battery Charging toggle.
4. Turn it off temporarily (select Turn Off Until Tomorrow).

If your phone immediately begins charging past 80%, you have solved the mystery. Note that if your routine is irregular or you frequently travel, this feature may struggle to predict when you need a full charge, making it seem like the phone is randomly pausing its charge.

2. The “Pocket Lint” Problem: Cleaning the Charging Port

If your phone will not charge at all, or if the charging cable feels “loose” and wiggles when plugged in, the charging port is almost certainly clogged. Every time you push a cable into the port, you are compacting dust, dirt, and pocket lint against the rear pins.

Over months or years, this lint becomes as hard as felt, physically preventing the metal contacts on the cable from touching the pins inside the phone.

How to Safely Clean Your iPhone Port:

1. Power Off: Turn your iPhone completely off to prevent any electrical shorts during the cleaning process.
2. Use the Right Tool: You must use a non-conductive tool. A wooden or plastic toothpick is ideal. Never use a metal paperclip, needle, or SIM ejector tool, as these will permanently scratch the delicate gold pins, destroying the port.
3. Scrape Gently: Insert the toothpick and gently drag it along the very bottom of the port. Do not press hard against the center “tongue” (in Lightning ports) or the central pin structure (in USB-C models).
4. Extract the Debris: You will likely pull out a surprising amount of compacted gray lint. Continue gently until the bottom feels hard and smooth.

After cleaning, plug the cable back in. It should now sit completely flush with the bottom of the iPhone with a satisfying “click.”

3. Thermal Throttling: Is Your iPhone Too Hot?

iOS has strict thermal limits. If your iPhone’s internal temperature gets too high, the operating system will forcefully cut power to the charging circuit to prevent battery swelling and permanent chemical degradation.

This commonly happens if you are:

• Charging the phone in direct sunlight (like on a car dashboard).
• Using a thick, unventilated case while fast-charging.
• Playing graphically intense games while plugged in.

If your phone feels hot to the touch and stops charging, simply unplug it, remove the case, and let it cool in a shaded area for 15 minutes before trying again.

4. Identify “Accessory Not Supported” Errors

If you see a popup stating “This accessory may not be supported,” the iPhone is rejecting the cable.

• MFi Certification: Ensure you are using an Apple-certified MFi (Made for iPhone) cable. Cheap gas-station cables often lack the necessary authentication chips, prompting iOS to block them for safety reasons.
• Internal Fraying: Even if an official Apple cable looks fine on the outside, the internal wires near the connector often snap from repeated bending. Try a different, known-working cable and power brick to isolate the hardware.

5. Force Restart the iOS Software

If the port is clean, the cable works on other devices, and the phone is not hot, a software crash might be preventing the battery management system from acknowledging the charge.

A Force Restart bypasses the operating system and reboots the hardware at a low level. For iPhone 8 and newer (including all Face ID models):

1. Press and quickly release the Volume Up button.
2. Press and quickly release the Volume Down button.
3. Press and hold the Side (Power) button. Keep holding it even when the “Slide to power off” slider appears.
4. Release the button only when you see the Apple logo appear on the black screen.

If you have exhausted all of these steps and the iPhone still refuses to accept a charge, the issue is likely a failed battery or a damaged internal charging IC (chip). At this stage, professional diagnostic testing by Apple Support or an authorized technician is required.

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