Xiaomi Redmi 9 is one of the most popular budget smartphones, but its standard 10W charging leaves much to be desired. Many users do not even suspect that the device supports fast charging of 18W - but only with the right settings and hardware. In this article, we will discuss how to activate accelerated charging, which adapters are suitable, and why sometimes the smartphone “refuses” to charge faster.
It is important to understand: Redmi 9 does not support proprietary technologies like Quick Charge 4+ or VOOC, but is compatible with the USB Power Delivery (PD) protocol and standard fast charging 5V/9V 2A. This means that for maximum speed you will need not only to enable the function in the settings, but also to use a compatible power supply and cable.
Checking support for fast charging on Redmi 9
Before you set up an accelerated charge, make sure your Redmi 9 supports it. Not all device modifications are equipped with the necessary electronics.
- 🔍 Processor model: Fast charging is only available on versions with a MediaTek Helio chip G80 (not to be confused with Helio G35 In the basic configuration. You can find out the model in the Settings → The phone. → Full specification.
- 📦 In the box with the supported model must be a power supply of 18 W (inscription) 5V⎓3A 9V⎓2A). If the 10W adapter – your smartphone does not support accelerated charging.
- 🔋 Test via app: Install Battery Monitor or Ampere and connect charging. If the current is greater than 1.5-2 A, fast charging works.
If your Redmi 9 doesn’t support 18W, don’t despair: even with a 10-watt adapter, you can speed up the process by 20-30% by optimizing your settings (more on this in the next section).
⚠️ Warning: Some vendors are replacing the original power supplies with cheap ones, unless the adapter has a Xiaomi logo or labeling. MDY-11-ES (18W), use it at your own risk - this can cause the battery to overheat.
How to enable fast charging in settings
The Redmi 9’s charging control is hidden in the developer menu and standard battery settings.
- Activate Developer Mode: Go to Settings → About Phone and 7 times click on the MIUI Version. a notification will appear "You became a developer".
- Enable Fast Charging: Return to Settings → Additional → Developer (or Advanced Settings → Developer Settings → Newer versions of MIUI). Find Charging Configuration or Charging Limitation and select Fast Charging (or No Limitations).
- Disable battery optimization for system processes: In the same developer menu, find MIUI Optimization and Background Optimization – disable them. This will prevent artificially slowing charging due to “energy savings.”
After this manipulation, the smartphone will start charging at the highest possible speed, but if you use a non-original cable or adapter, the system can automatically reduce power, as the “Slow Charging” notification signals.
Use the original cable USB-C|Connect the power supply 18 W (or with support) PD)|Activate the Developer Mode|Disable battery optimization|Check the temperature of the smartphone (not higher than 35)°C)-->
What adapters and cables are suitable for fast charging
Even if the Redmi 9 supports 18W, the wrong adapter or cable will make all the effort go away.
| Adapter type | Max. Power. | Support for Redmi 9 | Notes |
|---|---|---|---|
| Xiaomi 18W (MDY-11-ES) | 18 W (9V/2A) | ✅ Yes. | Best option, stable job |
| Third-party with PD support (e.g. Anker, Baseus) | 18-30 W | ✅ Yes. | You may need to manually enable PD in settings |
| Original Xiaomi 10W (MDY-08-EP) | 10 W (5V/2A) | ⚠️ Partially. | Charging 20–30% slower |
| Power supply from the laptop (USB-C, 45-65 W) | 45+ Watt | ❌ No. | Can damage the power controller? |
| Wireless charging (Qi) | 5-10 W. | ❌ No. | Redmi 9 does not support wireless charging |
Pay special attention to the cable: it should support current at least 2A. The original Xiaomi cables (included) are suitable, but if you use a third-party, look for the label USB 2.0 High-Speed or USB-C to USB-C marked 3A. Cheap cables often "suffocate" current to 1-1.5A, which is why charging is half slower.
⚠️ Warning: If you plug in an 18W adapter and still charge 10W, check the cable for damage. Often the problem is oxidized connector contacts. USB-C — Clean them with a cotton swab soaked in alcohol.
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If you frequently charge a powerbank smartphone, choose Power Delivery (PD)-enabled models (e.g. Xiaomi Mi Power Bank 3 Pro 20,000 mAh) that will provide a full 18W, unlike conventional powerbanks that are limited to 10-12W.
Why fast charging doesn't work: common problems
Even with the right settings, the Redmi 9 can “fail” to charge quickly.
- 🔥 Overheating: If the battery temperature exceeds 35°C, the system automatically reduces power. Solution: Remove the case, charge in a cool place or turn on Airplane Mode.
- 📉 Battery wear: After 500 charging cycles, battery capacity drops and fast charging shuts down. Check wear in the Battery Doctor app.
- 🔌 Failed port USB-C: If the contacts are bent or oxidized, the smartphone will not be able to "agree" with the adapter about the increased power.
- 🛠️ Software restrictions: In some regions (e.g. the EU), Xiaomi artificially limits charging power to 15 watts. Solution: change region in settings to India or China.
Critical error: If the smartphone gives a notification when you connect the charger, "This device is not supported," immediately turn it off, which means that the adapter is applying a non-standard voltage that the power controller can disable.
What to do if Redmi 9 is charged with jerks?
How to speed up charging without fast charging (alternative methods)
If your Redmi 9 doesn’t support 18W, you can speed up the process in other ways:
- Aircraft mode: Disables 4G, Wi-Fi and Bluetooth modules, reducing the load on the processor. Charging is accelerated by 15-20%.
- Background Disconnect: Close all applications through Recent → Close everything and turn off background activity in Settings → Battery → Battery Optimization.
- Use USB 3.0: Connect your smartphone to a USB 3.0 port (blue) on your PC or laptop, which delivers up to 1.5A instead of the standard 0.5A.
- Cooling: Put your smartphone on a metal surface (like a laptop radiator) – this will prevent trottling (automatic power reduction due to overheating).
These methods also work with fast charging: combining them, you can reduce the charging time from 2.5 to 1.5 hours. For example, if you simultaneously activate the aircraft mode and cool the smartphone, the charging current will increase from 1.8A to 2.2A.
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Even with a 10-watt adapter, you can speed up charging by 30 to 40 percent if you minimize the load on the processor and ensure cooling, and the key is to keep the battery from overheating above 40°C, otherwise it will degrade faster.
Myths about fast charging: what really hurts the battery
There are many myths surrounding fast charging, and we'll take a look at the most common ones.
- ⚡ "Fast charging kills a battery in a year, it's not true. Modern lithium-polymer batteries are designed to last 500-800 cycles, regardless of the charging speed. The main enemy is overheating and deep discharge (below 10%).
- 🔄 "You need to discharge to 0% once a month, which is a bad tip. For Redmi 9, the optimal range is 20-80.
- 🛌 "You can't charge overnight. MIUI It has built-in protection: after 100%, the power goes off, and when it falls to 99%, it turns on again.
The most dangerous thing for the Redmi 9 battery is the use of cheap wireless charging. They often have no temperature control and can heat the battery to 50 ° C, which reduces its life by 2-3 times. If you want wireless charging, choose models with Qi 1.2+ certification and a built-in fan (for example, Xiaomi Wireless Charging Pad).