Why fast charging on Xiaomi disappeared: the reasons and how to return the speed

Have you noticed that your Xiaomi suddenly stopped charging at the same speed? Instead of the manufacturer's promised 50-120 watts, the process stretches for hours, and the indicator shows "Slow Charging"? The problem is found on models from the Redmi Note 10 Pro to the flagship Xiaomi 14 Ultra - and not always associated with a breakdown. 80% of the time, the settings, firmware or accessories are to blame, not the smartphone itself.

We analyzed service center data and user feedback to compile a checklist of reasons, from banal port pollution to hidden MIUI limitations. In this article, you will find step-by-step diagnostic instructions, a charger compatibility table and answers to frequent questions. Pay special attention to the section on “hidden energy saving mode” – its activation zeroes the charging speed even on new models.

—— • ——

1. Problems with charger or cable

The first thing to check is the charging kit. Even the original Xiaomi accessories fail over time, and uncertified ones may not support Quick Charge, Power Delivery or the branded HyperCharge protocols.

According to tests from DXOMARK, cheap cables lose up to 40% of their power due to poor quality copper veins.

• 🔌 Charging is interrupted at the slightest movement of the cable
• 🔥 adapter housing or connector USB-C heats up over 50°C
• ⚡ The screen displays “Slow Charging” even with the original unit.

How to check:

1. Connect your smartphone to another charger that supports Quick Charge 3.0+ or PD (e.g. from a MacBook or iPad Pro).
2. Try another cable, preferably one with USB-IF Certified.
3. Measure the current with the Ampere app (should be ≥2A for fast charging).

⚠️ Note: Some Xiaomi models (e.g. Redmi Note 12 Pro)+) They block fast charging when using cables without an authentication chip.

2.Contamination of the USB-C port or contact oxidation

The USB-C port is the most vulnerable place to dust and moisture. According to service centers, 35% of requests for slow charging are due to pollution. Dust and pile from clothing create a barrier between contacts, and oxidation (green plaque) increases resistance.

How to clean the port yourself:

• 🧹 Use a toothpick with cotton wool dipped in alcohol (90%+).
• 💨 Blow the port with compressed air (cylinder for equipment).
• 🔍 Check contacts for blackening or green plaque – this is a sign of oxidation.

⚠️ Note: Do not use metal objects (needles, paper clips) - they can damage the contacts. If after cleaning the problem remains, the port may be mechanically deformed (for example, after falling).

3. Software restrictions: hidden MIUI settings

MIUI has several "secret" features that can artificially limit charging speeds, most often to blame:

1. Battery Optimization Mode (Settings → Battery → Charging Optimization) If enabled, the smartphone charges slower after 80-90% to save battery life.
2. Background power restriction for applications (e.g. Google Play Services may block fast charging).
3. Hidden energy saving mode that is activated after updates or resets.

How to disable restrictions:

1. Go to Settings → Battery → Battery settings → Charging optimization and turn off the function.
2. In Settings → Applications → Battery Management, check if there are any limitations to system processes.
3. Reset the battery settings: Settings → System → Reset settings → Reset the battery and performance settings.

⚠️ Note: Some models (e.g. Xiaomi) 13T) post-update MIUI 14, a bug appears with a slow-charging stick. Solution is a forced reboot (squeeze Power). + Volume up for 10 seconds).

4. Damage to the battery or power controller

If a smartphone is older than 2 years, the cause may be a degradation of the battery. Lithium polymer batteries lose capacity and increase internal resistance, which leads to:

• 📉 The drop in charging speed after 50-60%
• 🔥 Overheating of the body during charging
• ⚡ Unintentional disconnections from charging

How to check the status of the battery:

1. Install the AccuBattery app and check the Battery Health score (normal: 80-100%).
2. Enter the #4636### code in the phone number, select Battery Information and check Level (should match the actual percentage).

Critical signs of failure of the power controller:

💡

If the battery is swelling (the case of the smartphone is "unplugged"), immediately disconnect it from charging and contact the service. Continuing use is dangerous!

5. Failures after firmware update

MIUI updates sometimes bring not only new features, but also bugs. For example, after the release of MIUI 14.0.4, Xiaomi 12T users complained massively about the loss of fast charging, the reason is a conflict of drivers of the power controller.

How to return the charging speed after the update:

• 🔄 Make a reset to the factory settings (pre-save data!).
• 📥 Install the beta version of the firmware through MIUI bootloader (if available for your model).
• 🔧 Reverse to the previous version via Fastboot (instruction below).

Firmware rollback instructions:

1. Download the firmware archive for your model from xiaomifirmwareupdater.com.


2. Unpack the archive and connect the phone to the PC in Fastboot mode (clip Power + Volume down).




3. In the command line, do:




fastboot flash recovery recovery.img




fastboot flash boot boot.img




fastboot reboot




4. After rebooting, reset the settings.

⚠️ Attention: Firmware rollback may result in data loss and warranty void. Before the procedure, check if your model supports unlocking the bootloader.

External factors: temperature and humidity

Xiaomi automatically reduces charging speeds at extreme temperatures, according to the technical documentation, the optimal range for fast charging is 10 ° C to 35 ° C. When going beyond these limits, protection works:

• ❄️ Below. 10°C: Charging is limited to 5V/1And.
• 🔥 Above 35.°C: speed drops to 50% maximum.
• 💧 Wet weather. >80% (for example, after rain) can trigger a moisture sensor in the port.

How to check the temperature:

1. Install the CPU Monitor or AIDA64 app.
2. Check the battery temperature in the Sensors section.
3. If the temperature is above 40°C, let the phone cool for 15-20 minutes.

💡

If the smartphone overheats even during normal use, it may indicate a faulty battery or thermal paste on the processor.

7 Hardware malfunctions: when without service can not do

If all previous steps have failed, the problem is likely hardware, and according to statistics from Xiaomi service centers, the most common are:

• 🔋 Battery bloating (requires replacement).
• 🔌 Breakage of the power supply plume (for example, after a fall).
• 🔧 Failure of the charging controller (chip on the motherboard).

Signs of critical failure:

⚠️ Warning: If the smartphone is warranty, don't disassemble it yourself! Opening the case will void warranty obligations. Contact the authorized Xiaomi service center with a check and a box.

—— • ——

FAQ: Frequent questions about fast charging Xiaomi