Why you need fast charging on the Mi 9 SE and how it works
Xiaomi Mi 9 SE is a compact flagship of 2019, which still remains relevant due to the balanced characteristics. One of the key advantages of the model is the support of Quick Charge 3.0 (18 watts) fast charging technology, allowing you to recover up to 50% of battery power in just 30-40 minutes. However, many users are faced with the fact that the smartphone charges slowly, despite the presence of a compatible adapter.
The fact is that fast charging on the Mi 9 SE is not always automatically activated, and this may be due to firmware settings, cable malfunction, using a non-original charger, or even software restrictions from Xiaomi. In this article, we will discuss all possible ways to enable Quick Charge, and also explain how to check whether the technology is working on your device.
Before you get to the settings, it is important to understand: Mi 9 SE Supports Quick Charge 3.0 (up to 18 watts), but only if three conditions are met: 1) an original or certified power adapter with support QC 3.0, 2) of quality USB-cable (preferably Type-C), 3) no software restrictions MIUI.
If at least one of the conditions is not met, the smartphone will be charged in standard mode (5-10 W).
Checking support for fast charging on Xiaomi Mi 9 SE
Before you try to enable Quick Charge, make sure your device supports this technology at all. Although the Mi 9 SE is officially equipped with fast charging, some modifications (for example, for the Chinese market) may have limitations.
How to check support: Method 1. Look at the smartphone box — if it says Quick Charge 3.0 or 18W Fast Charging, then the technology is supported. Method 2. Install the AccuBattery app (available on Google Play) and check the Charging section. If the adapter is connected to 15-18 watts, Quick Charge works. Method 3. Type ##4636## in the dial number, go to Battery Information and see the current charging power.
If neither method shows fast charging, the problem may lie in:
- 🔌 Unoriginal or damaged cable (especially if it is not Type-C).
- ⚡ Charger without Quick Charge 3.0 support (even if it is 18 watts).
- 📱 Programmatic limitations in MIUI (For example, after updating the firmware).
- 🔋 Battery wear (if the smartphone is older than 2-3 years, the battery may not support high currents).
How to enable fast charging through MIUI settings
In some versions of MIUI firmware, fast charging is disabled by default to extend battery life. To activate it, follow the following steps:
- Open Settings → Battery and Performance.
- Go to Battery Settings (or additionally, depending on the MIUI version).
- Find the Quick Charge option (could be called Quick Charge or Accelerated Charge).
- Activate the switch. If it's not there, your firmware doesn't support manual control.
☑️ Preparation for Quick Charge inclusion
If there is no quick charge in the settings, this may mean:
- 📲 You have custom firmware installed (like LineageOS or Pixel Experience) where Quick Charge is managed differently.
- 🔄 Firmware MIUI outdated – update it through Settings → The phone. → Updating the system.
- 🔧 Manufacturer has disabled the option for your region (relevant to Chinese versions of Mi 9) SE).
⚠️ Note: On some versions MIUI (for example, MIUI 12.5 and later) fast charging can be automatically turned off at high battery temperature (above 40)°C) or when using cheap cables: If the smartphone heats up while charging, try removing the case or moving it to a cool place.
Choosing the Right Charger and Cable
Even if fast charging is enabled in the settings, it won't work without a compatible adapter and cable. Xiaomi Mi 9 SE requires:
- 🔌 Power adapter with Quick Charge 3.0 support (18W) or USB Power Delivery (PD). The original adapter from Mi 9 SE It meets these requirements.
- 🔗 Type-C high current cable (better original or certified, for example, from Anker or Baseus).
If you use a third-party charger, pay attention to its specifications, for example, adapters from Samsung (with Adaptive Fast Charging support) or OnePlus (Dash Charge) may not be suitable, as they use proprietary protocols.
| Adapter type | Support for Quick Charge 3.0 | Max Power for Mi 9 SE | Recommendation |
|---|---|---|---|
| Original from Mi 9 SE | ✅ Yes. | 18 W. | ⭐ Best choice. |
| Third-party with QC 3.0 (e.g. Anker PowerPort) | ✅ Yes. | 15-18 W | 👍 Good alternative. |
| Adapter from Mi 8/9 (Quick Charge 4+) | ✅ Yes (backward compatibility) | 18 W. | 👍 It fits. |
| Standard. USB-adapter (5 watts) | ❌ No. | 5-10 W. | ❌ Not recommended |
| iPhone Adapter (5-12 W) | ❌ No. | 7-12 W | ⚠️ Slow charging. |
Critical: If you use wireless charging, Quick Charge won’t work. Xiaomi Mi 9 SE doesn’t support fast wireless charging – the maximum power in this case will be 10 watts.
Software limitations: why fast charging might not work
Sometimes Quick Charge is not turned off because of hardware problems, but because of software.
- 📱 Outdated firmware MIUI. In older versions (below). MIUI 11) fast charging may not work stable. Update your smartphone via Settings → The phone. → Updating the system.
- 🔧 Battery optimization. MIUI There's a Smart Optimization feature that can limit charging current. Turn it off in Settings. → Battery → Battery settings → Optimization.
- 🛠️ Castomware: If you have installed an informal firmware (like LineageOS), Quick Charge may not work without additional cores or patches.
- 📉 Battery wear: If the battery is worn out by more than 30%, the smartphone can automatically reduce the charging power.
If you suspect the problem is firmware, try resetting to factory settings: 1. Go to Settings → About Phone → Settings Reset. 2. Select Reset all settings (does not delete files, but resets system settings). 3. After rebooting, check charging again.
What if Quick Charge does not work after resetting?
⚠️ Note: Some users are trying to enable fast charging via the engineering menu (#4636## → Battery information → Fast charging. However, on the Mi 9 SE This method often doesn't work and can cause system failures.
Checking the real charging speed: applications and tests
How do you know that fast charging really works? It's not always enough to look at the status bar indicator - it can show "Fast Charging" even at 10 watts. For accurate verification, use specialized applications:
- 📊 AccuBattery – shows the current charging power, battery temperature and wear.
Run the test: 1. Discharge the smartphone to 10-15%. 2. Connect the original adapter and start AccuBattery. 3. After 10-15 minutes, check the power schedule:
15-18 watts – Quick Charge works correctly.
10-12 W – charging is in standard mode.
Less than 5 watts – problems with cable, adapter or battery
💡
If the charging power jumps (it’s 18 watts, then 5 watts), try to turn off all background apps or reboot your smartphone. Sometimes processes like Google Play Services or MIUI Optimization interfere with the stable operation of Quick Charge.
Frequent problems and their solutions
Even after all the settings, fast charging can be unstable. Consider typical situations and how to fix them:
| Problem. | Possible cause | Decision |
|---|---|---|
| The charge is slow, despite the QC-adapter | Unoriginal cable or damaged Type-C connector | Try another cable or clean the port of dust |
| The smartphone is heating up and reduces power | High battery temperature (above 40°C) | Remove the cover, move the phone to a cool place |
| Quick Charge only works when the screen is off. | Limit MIUI to save energy | Turn off Battery Optimization in Settings |
| The adapter is warming and shutting down. | Poor-quality charger or overload | Replace the adapter with an original or certified adapter |
If none of the methods helped, there may be a problem with the hardware:
Battery wear (replacement required).
Damage to the power controller (repair in the service center).
Type-C connector malfunction (check for oxidation or mechanical damage).
💡
If fast charging has worked before but Suddenly has stopped, check the cable and adapter first, and then the MIUI settings. 80% of the time, it’s the cable and adapter that’s the problem.