Xiaomi Redmi 9 is one of the most popular budget smartphones, but many users face the problem of slow charging. Even with a proprietary charger, the process can stretch for hours. The reason often lies in the default fast charging function or incorrect MIUI settings. In this article, we will analyze all the working ways to activate accelerated charging, check the compatibility of equipment and give recommendations for safe use.
It’s important to understand that Redmi 9 supports Quick Charge 3.0 (18W), but the manufacturer sometimes limits its operation to extend battery life. Also, not all chargers and cables are capable of providing maximum speed. We have tested all methods on MIUI 12-14 firmware and are ready to share proven solutions – from basic settings to hidden options of the engineering menu.
1. Checking the compatibility of the charger and cable
Before you enable fast charging in your settings, make sure your hardware supports Quick Charge 3.0/4.0 or Power Delivery (PD.) Xiaomi Redmi 9 is officially certified to work with charges up to 18W, but in practice, the speed depends on three factors:
- 🔌 Charger: Must support protocols QC 3.0 or PD (For example, the original RAM from the Redmi Note 9 Pro or Mi 10 Lite kit).
- ⚡ Cable: requires USB-Type C with support for high currents (it is better to use Xiaomi branded cable with a marking) 5A).
- 📱 Battery status: If the battery capacity falls below 80% of the original, the charging speed automatically decreases.
How do you check your current charging power? Connect your smartphone to the network and open the Security → Battery app. The consumption chart should show "Fast Charging" or a power value above 10W. If you see 5W, your RAM or cable doesn't fit.
⚠️ Note: Use of uncertified chargers with higher power 20W The power controller Redmi 9 can overheat.The most safe power for this model — 18W.
2. Enabling fast charging in MIUI settings
In most cases, the fast charging function is disabled by default. To activate it, follow the following steps:
- Open the settings → Battery and performance.
- Go to the Battery Settings section.
- Find the "Fast Charging" option (or "Accelerated Charging" in new MIUI versions) and switch the slider to the "On" position.
- Confirm the action by pressing OK in the pop-up window.
If the Fast Charging option is not on the menu, your firmware is hiding this option, and one of the alternative methods described below will help, and check if you have a power saving mode that automatically turns off accelerated charging.
Turn off the power saving mode|Use the original Type-C cable|Connect the charger to the socket (not USB-port)|Check the battery temperature (should be) < 40°C)|Update MIUI last-minute-->
3. Hidden settings of the engineering menu (#4636##)
If the standard settings don't work, you can activate fast charging via the engineering menu, which works on most versions of MIUI, but you need to be careful:
- Open the phone app and enter the combination: ##4636##
- In the menu that opens, select Battery Information.
- Scroll down and find the "Fast Charge Config" (or "AC Charge").
- Set Enable or 1 (depending on the menu version).
- Reboot your smartphone.
Important: Once activated through the engineering menu, the charging speed can exceed factory limits (up to 20W), which shortens battery life.
What to do if the engineering menu is not opened?
4. Optimization of charging through ADB-Teams (for advanced teams)
For users familiar with Android Debug Bridge (ADB), there is a way to force fast charging through the command line.This method is guaranteed to work on the Redmi 9 with a MediaTek Helio G80 processor, but requires a connection to a PC:
- Activate Developer Mode: Go to Settings → About Phone and click on MIUI Version 7 times.
- Return to Settings → Additional → For developers and enable USB debugging.
- Connect your smartphone to your PC, open the Command Prompt (Windows) or Terminal (macOS/Linux) and enter adb shell su echo 1 > /sys/class/power_supply/battery/fast_charge_enabled
- Reset the device.
If the team doesn’t work, try an alternative:
adb shell
su
setprop persist.sys.fastcharge true⚠️ Attention: Use ADB-commands without experience can lead to software failures. Before execution, back up your data through Settings → System system → Backup.
5. Charger compatibility table for Redmi 9
Not all charging is equally efficient. Below is a table of proven models that provide the highest charging speed for the Redmi 9:
| Model charger | Power | Protocol | Charging speed (0–50%) | Notes |
|---|---|---|---|---|
| Xiaomi Mi 18W Fast Charge (from the Redmi Note 9 Pro kit) | 18W | Quick Charge 3.0 | ~45 minutes. | The best option, there is no overheating |
| Anker PowerPort III Nano | 20W | Power Delivery | ~40 minutes. | Requires a USB-C cable to USB-C |
| Samsung EP-TA200 (from the Galaxy S10 kit) | 15W | Adaptive Fast Charge | ~55 minutes | Works but is slower than QC 3.0 |
| Baseus 30W GaN | 30W | Power Delivery | ~35 minutes (up to 50%) | Risk of overheating with prolonged use |
| Standard RAM from the Redmi 9 set | 10W | No quick charging. | ~120 minutes | Does not support QC/PD |
💡
If you frequently charge your smartphone at work or in your car, buy a portable RAM with Power Delivery (e.g. Xiaomi Mi Power Bank 3 Pro 20000mAh) that supports fast charging and is battery-safe.
6.Why can fast charging not work?
Even after you turn on all the settings, the charging speed sometimes remains low.
- 🔥 Battery overheating: if the battery temperature exceeds 40°C, the system automatically reduces power. Let the smartphone cool for 10-15 minutes.
- 🛠️ Battery wear: After 500 charging cycles, the capacity drops and fast charging is turned off.
- 📴 Background: Games or updates to backgrounds consume energy. Close all applications before charging.
- 🔄 Outdated firmware: in MIUI 12.0.3 and below were bugs with recognition QC-Update to the latest version of the charger.
If the problem persists, try resetting the battery settings:
- Go to Settings → Applications → Application Management.
- Click on the three dots in the top right corner and select Reset app settings.
- Confirm the action and restart the smartphone.
💡
Fast charging on the Redmi 9 works stably only at a battery temperature of 10-35 ° C. In hot weather or in heavy use, the speed will be automatically limited.
7. Alternative methods of accelerating charging
If standard methods don’t help, try these proven techniques:
- ⚡ Aircraft mode: Disables all radio modules (4G, Wi-Fi, Bluetooth, reducing charging time by 15-20%.
- 🔕 Disconnect Sync: Go to Settings → Google Accounts and Temporarily Deactivate Automatic Sync.
- 📵 Using high-quality cable: replacing cheap USB-cable-certified USB-IF It can increase the speed by 30%.
- 🔄 Charging cycles: instead of fully discharged to 0%, charge your smartphone more often (e.g. 20% to 80%) to extend the life of the battery.