Reasons why iPhone reports slow charging

Some iPhones running iOS 26 are showing a “slow charging” warning when using older accessories, but this doesn’t have much of an impact on the device.

iPhone running iOS 26 reported slow charging due to users using old chargers. Photo: TechWiser .

Some iPhone users running iOS 26 recently noticed that the lock screen shows an estimated time to charge to 80%. However, if you are not using a fast charger, the device will display a “slow charger” status.

According to experts, this message often comes from users using low-power chargers or old charging cables. To achieve fast wired charging speeds, Apple recommends a charger with a capacity of 30W or higher and a standard USB-C cable.

New iPhone models, including the iPhone 17, have significantly larger batteries than the devices from five years ago. Users who have just upgraded their devices may not have had time to change compatible accessories. For example, if you are still using a USB-A charger with a rectangular port, the maximum charging speed is only 7.5W. In this case, a full charge can take more than 3 hours.

When paired with the right accessories, the iPhone supports a steady 20–30W fast charging rate, allowing it to charge from 0% to 50% in just under 30 minutes. As for the brand, Apple says there are no significant differences. Any USB-C charger that supports Power Delivery will handle high-speed charging.

With the iPhone 17, Apple also introduced a new Dynamic Charger, optimized for speed and power consumption. However, the difference compared to other options is not much. Users can choose products from popular brands such as Anker, Belkin with lower costs but still ensure quality.

In addition to wired charging, users may also encounter a “slow charging” warning when using older Qi-standard wireless chargers with a capacity of less than 10W. To improve, 9to5Mac recommends that users use genuine MagSafe accessories or chargers that support the Qi2 standard. New iPhone models currently allow wireless charging at a maximum speed of 25W.

For example, Belkin's MagSafe charger supports 25W speeds and has a built-in charging dock for AirPods, while simpler charging docks can still reach 15W, which is fine for basic needs.

Source: https://znews.vn/ly-do-khien-iphone-sac-cham-post1590465.html