Why Your iPhone Charges Slowly Sometimes

Your iPhone should charge from 0% to 50% in about 30 minutes with a proper fast charger, but sometimes it feels like it's barely moving. This frustrating slowdown can happen for many reasons-some obvious, others hidden. Understanding what affects charging speed helps you fix the issue and get back to full power quickly. A normally functioning iPhone with a good charger and cable should fully charge in under 2 hours, but when something's wrong, it might take twice as long.

In this article, we'll explore the seven most common reasons for slow iPhone charging and how to solve each problem effectively.

1. Power Source Issues

Using Low-Power USB Ports (Computer/Old Adapters)

Many people plug their iPhones into laptops or old USB wall adapters without realizing these often deliver barely enough power for charging. Standard USB-A ports on computers typically provide just 5W (0.5A), which is painfully slow compared to modern fast chargers. Even some wall adapters labeled as "iphone charger" may only be the basic 5W model included with older iPhones. For context, Apple's current 20W charger delivers four times more power, cutting charging time significantly. Always check your power source's output-if it's 5W or less, that explains your slow charging.

Damaged/Wrong Wattage Charging Bricks

Not all charging bricks work the same way with iPhones. While Apple devices are designed to work safely with various power sources, using an underpowered or damaged adapter will slow things down. A charger rated for 5W will work, but one rated for 12W or higher will charge much faster (iPhones support up to 27W for fastest charging). Physical damage matters too-if your charger's plug is loose, the cable won't stay firmly connected, causing intermittent charging that feels slower overall. Try testing with another adapter to see if your current one might be the problem.

Wireless vs. Wired Charging Speed Differences

Wireless charging is convenient but significantly slower than wired charging-typically capping at 7.5W for standard Qi chargers (15W for MagSafe). The conversion of electricity to magnetic fields and back to electricity creates energy loss as heat, which further slows the process. If you regularly use wireless charging overnight, the speed difference may not matter. But if you need quick power before heading out, switching to a wired connection with a proper fast charger makes a huge difference. Also, improper alignment on wireless chargers can reduce efficiency, making charging even slower.

2. Cable Problems

A damaged or low-quality charging cable is one of the most common-yet overlooked-reasons for slow iPhone charging. Frayed wires, bent connectors, or internal breaks can severely limit power transfer. Even cables that appear fine might have hidden damage from being bent too sharply or pulled too hard. Apple-certified Lightning cables (or high-quality MFi-certified alternatives) ensure proper power delivery, while cheap knockoffs often fail to meet the necessary specifications. If your cable feels loose in the port or only charges when positioned a certain way, it's likely hindering your charging speed. Try a different cable to see if that solves the issue.

3. Background Activity Drain

Your iPhone might charge slowly simply because it's using power as fast as it's receiving it. Background app refresh, automatic updates, and location services continue running while charging, consuming energy that would otherwise go to the battery. If your phone feels warm during charging, that's a sign it's working hard-and lithium-ion batteries charge slower when warm. Putting your iPhone in Airplane Mode or Low Power Mode while charging can dramatically speed things up by reducing background activity. Also, avoid using power-hungry apps like games or video streaming while charging, as they significantly slow down the process.

4. Temperature Effects

iPhones are designed to protect their batteries by slowing charging in extreme temperatures-both hot and cold. In warm environments (above 95°F/35°C), your iPhone may throttle charging speed to prevent battery damage. Similarly, cold conditions (below 32°F/0°C) can temporarily reduce battery efficiency. If you leave your phone in direct sunlight, near a heater, or in a hot car, it might charge much slower than usual. For fastest charging, keep your iPhone at room temperature (around 68°F-77°F/20°C-25°C). Removing thick cases during charging can also help dissipate heat better.

5. Software & Settings

Sometimes, software issues cause unexpected charging slowdowns. A pending iOS update might include battery management improvements that affect charging behavior. Background processes like iCloud backups or photo syncing can also drain power during charging. Check for software updates in Settings > General > Software Update, as newer versions often optimize power delivery. Additionally, features like Optimized Battery Charging (which slows charging above 80% to prolong battery life) can make charging seem slower-though this is intentional for battery health. If you need a full charge quickly, temporarily disabling this feature in Settings > Battery > Battery Health can help.

6. Hardware Issues

If all else fails, your iPhone's hardware might be the problem. A worn-out battery (especially after 500+ charge cycles) loses efficiency and may charge slower. Dirt or lint in the Lightning port can prevent proper cable connection, reducing charging speed-carefully cleaning it with a toothpick or compressed air might help. In rare cases, a failing charging port or power management chip could be the culprit. Apple's built-in battery health tool (Settings > Battery > Battery Health) can show if your battery is significantly degraded. If your iPhone is old and consistently charges slowly, a battery replacement might be the best solution.

Conclusion

Slow iPhone charging is usually fixable once you identify the cause-whether it's a weak power source, damaged cable, background processes, or temperature issues. For fastest charging, use a high-quality 20W or higher USB-C power adapter with an Apple-certified cable, keep your iPhone at moderate temperatures, and minimize background activity while charging. If you're looking for a reliable fast charger, Anker's iPhone chargers are widely praised for their consistent performance and durability. With the right setup, you can keep your iPhone charging quickly and efficiently for years to come.