Why fast charging doesn’t work on Xiaomi Redmi 8T: a full analysis of the causes and solutions

The Xiaomi Redmi 8T, with its capacious 5,000mAh battery and support for 18W fast charging, should recover charge in hours. But what if the smartphone stubbornly ignores the "fast" adapters and charges like the old Nokia 3310? The reasons lie in both iron malfunctions and software failures of MIUI.

In this article, we’ll look at 12 key reasons why the Redmi 8T can slow down charging, from the cluttered wear of the cable to the hidden power saving settings, how to diagnose a problem without visiting a service center, what engineering codes will help check the battery status, and why Xiaomi’s original power supply doesn’t always guarantee 18W.

Spoiler: 30% of the time, it’s not the phone that’s to blame, but a cheap cable with thin veins that’s physically unable to pass current above 1A. But there are more insidious reasons, such as resetting the power controller after updating MIUI 12.5+.

1. Power supply and cable check: why 18W turns into 5W

The first thing to rule out is that the charging accessories don't match the Redmi 8T requirements. Even if the adapter says "18W," it doesn't guarantee real power.

• 🔌 Use the original unit from the set (model) MDY-11-ED or MDY-11-ES). Fakes are often only given out. 10W.
• ⚡ The cable should support Quick Charge 3.0. Cheap no-name cables are limited to 0.5-1A.
• 📊 Install the AccuBattery app (free on Google Play) and it will show the real charging current. 18W: 2.5-3A.

Simple test: connect the Redmi 8T to a known working adapter from another device (for example, from the Redmi Note 10 Pro). If charging went faster, the problem is in your power supply.

⚠️ Note: If you are connected to a PC or a weak adapter (5W) The phone shows “charging is complete” by 80-90%, this is a sign of a faulty power controller – diagnostics are required in the service.

2. Software glitches: why MIUI slows charging

MIUI has hidden power saving settings that can artificially limit charging current, most often after:

• 📲 Firmware updates (especially with MIUI 11 on MIUI 12.5+).
• 🔄 Reset to factory settings.
• 🛠️ Installation of custom cores or modified firmware.

How to check:

1. Go to Settings → Battery → Battery settings.
2. Turn off the option "Optimized Charging" (if enabled).
3. In Settings → Special Features → Developer Settings, find the item “Debugging by USB” and turn it on (this will unlock hidden menus).

For the discharge of the power controller:

1. Enter the code in the phone app: ##4636##.
2. Select "Battery Information".
3. Click "Reset Battery Statistics" (does not delete data, only resets calibration).

3. Battery wear: when 5,000mAh is no longer 5,000mAh

The Redmi 8T, with its capacious battery, loses capacity over time — after 300 to 500 charging cycles, the real capacity can drop to 60 to 70 percent of its value, which leads to:

• 🐢 Slow charging (controller limits current for "sparing" mode).
• 🔥 Overheating when trying to charge fast (the phone automatically reduces power).
• 📉 A sharp drop in the percentage of charge from 30% to 1%.

How to check the wear:

1. Install AccuBattery and see the Battery Health section.
2. If the capacity is below 2000 mAh, the battery must be replaced.
3. Enter the engineering code: ##6484## → "Battery Info" → check the parameter MB_06 (should be close to 5000).

⚠️ Note: If the phone is over 45 when charging°C and the battery is swollen (see above the raised screen) – turn off power immediately and do not use the device until the battery is replaced!

4.Problems with USB-C connector: oxidation, pollution, mechanical damage

The Redmi 8T USB Type-C connector is one of the most vulnerable areas, and dust, moisture, or mechanical damage to the contacts can cause:

• 🔌 Unstable connection (charging is going, then interrupted).
• ⚡ Power drop (the phone thinks it is connected to a weak source).
• 📵 Complete inoperability of fast charging.

How to clean the connector:

1. Turn off the phone and remove it. SIM-map.
2. Take a toothpick (not metal!) and carefully remove the garbage from the connector.
3. Moisten the cotton swab in isopropyl alcohol (90%+) and wipe the contacts.
4. Let dry for 10-15 minutes before connecting.

If the contacts are bent or missing, the connector needs to be replaced. ₽.

5. Hidden MIUI settings: Disabled fast charging in the developer menu

In MIUI 12.5 and later, the fast charging function can be software-disabled – for example, after resetting or updating.

1. Activate Developer Mode: Go to Settings → About Phone and click on MIUI Version 7 times.
2. Back to Settings → Additionally. → For developers.
3. Find the item "Charging configuration" (or "Fast Charge" in English firmware).
4. Make sure you select either "Enable" or "Quick Charge" mode.

If you don’t have a paragraph, try resetting the settings via ##7378423## (Service Tests → Battery Test menu).

💡

After enabling fast charging in the developer menu, restart the phone – this will apply changes at the kernel level.

6. firmware problems: when software is to blame

Sometimes slow charging is the result of an incorrectly installed update or conflict with custom modules (for example, Magisk or Xposed).

• 📱 Charging is only in the off state.
• 🔄 The percentage of charge "hangs" on one value.
• ⚠️ A notification appears “Use the original charging adapter” (even with the original unit).

Decisions:

1. Reverse to the previous version of MIUI via the Mi Flash Tool (instructions on miui.com).
2. Removal of custom modules (if installed).
3. Reset to factory settings (pre-make a backup!).

For advanced users: check the charging logs through ADB:

adb shell dumpsys battery

Look for lines from charge_counter and current_now — They'll show real current.

External factors: temperature, humidity, magnetic fields

Fast charging can be automatically turned off when:

• 🌡️ Temperature below 0°C or higher than 40°C (controller blocks high current).
• 💧 Increased humidity (even condensation on the board can cause protection to work).
• 🧲 Exposure to magnetic fields (for example, if you charge your phone wirelessly next to a Redmi) 8T).

Decisions:

• Charge your phone in a room with a temperature of 10-35 ° C.
• Avoid direct sunlight (do not leave it on the windowsill).
• Do not put your phone on metal surfaces (refrigerator, radiator).

💡

If the phone overheats when charging, remove the case - it can block the heat sink.

FAQ: Frequent questions about the Redmi 8T charging