Fast charging on Redmi 9: how to turn on and configure correctly

Why Redmi 9 Charges Slowly and What to Do About It

Owners of Xiaomi Redmi 9 often face the problem of long battery charging - the device can recover energy for 4-6 hours, even if connected to the original power supply. The reason lies not only in the battery capacity (5020 mAh), but also in the default fast charging function. The manufacturer limits the charging current power to extend the battery life, but if necessary, the user can activate the accelerated mode himself.

It’s important to understand that Redmi 9 supports Quick Charge 3.0 (18W), but it requires not only a compatible adapter, but also the right software settings. In this article, we’ll look at all the ways to enable fast charging, from hardware checks to hidden options in the developer menu, and you’ll also learn which chargers and cables are guaranteed to work with this model, and how to avoid common errors that lead to overheating or accelerated battery wear.

Checking support for fast charging on Redmi 9

Before you try to activate Quick Charge, make sure your device is technically capable of running in this mode. Xiaomi Redmi 9 (model number M2004J19C) is equipped with a power controller that supports QC 3.0 and USB Power Delivery (PD) protocols, but there are nuances:

• 🔋 Original power supply: Complete with the phone comes the adapter on 10 Watt (5V/2A). It does not support fast charging – for activation. QC 3.0 need a block of power 18 Watt.
• 🔌 Type-C Cable: Use only certified high-current cables (e.g., original from Xiaomi or labeled cables) USB-IF). Cheap analogues can limit power.
• 📱 Version. MIUI: On firmware older MIUI 12.5 The fast charging function can be hidden. Update the system via Settings → The phone. → Updating the system.

To check the current charging speed:

1. Connect the phone to the charger.
2. Open the Security app (shield icon).
3. Go to the Battery section → Charging state.
4. Look next to the power label, if it's above 10 watts, fast charging is already active.

Methods of enabling fast charging

If your Redmi 9 supports Quick Charge but the mode doesn’t activate automatically, try the following methods: Start with the simplest and move on to the more complex ones if the result isn’t achieved.

1. Use of a compatible charger

The most reliable way is to connect the phone to an adapter that supports QC 3.0 or PD.

Once you have a compatible adapter on, the phone should automatically determine support for fast charging. If that doesn't happen, move on to the next step.

2. Activation through hidden MIUI settings

In some versions of the firmware, the fast charging option is hidden to enable it:

1. Open the phone app and dial the combination: ##4636##
2. In the menu that opens, select Battery Information.
3. Check the charge technology line. If it says Standard, tap it several times until the Quick Charge option appears.
4. Confirm your choice and restart your phone.

Use the original Type-C cable

Connect the adapter ≥18 W

Update MIUI to the latest version

Check the battery temperature (should be) <40°C)-->

3. Include through the developer menu

If previous methods have not worked, activate the mode through the developer options:

1. Go to Settings. → The phone.
2. Tap 7 times on the line MIUI version until the notification appears You became a developer!
3. Go back to the main settings menu and open a new section for developers.
4. Find the option Charge Configuration (or Fast Charge) and select Included.
5. Save the changes and restart the device.

💡

If the developer menu does not have the option “Charge configuration”, try resetting the network settings: Settings → SIM-maps and mobile networks → Resetting network settings. Sometimes it helps unlock hidden features.

Common Mistakes and How to Avoid Them

Incorrectly activating a fast charge can cause the battery to overheat, wear faster, or even fail. Here are typical Redmi 9 users’ mistakes and ways to prevent them:

⚠️ Warning: Never use chargers with power above 30W (such as 65W or 100W laptop adapters).The Redmi 9 power controller is not designed to handle such loads that could cause battery bloating or damage to the motherboard.

• 🔥 Overheating during charging: If the phone body heats up above 40°C, immediately disconnect it from the grid. Fast charging automatically shuts off at high temperatures. Solution: charge your phone in a cool place with your case removed.
• ⚡ Use of uncertified cables: Cheap unlabeled cables can limit current to 0.5-1A, negating the benefits QC 3.0. Check the cable for logo USB-IF or 5A.
• 📉 Charging to 100%: Keeping charge at 100% continuously reduces battery life. Optimal range is 20-80%. Enable charge limitation in battery settings (Settings) → Battery. → Settings → Charge limitation).

Another common problem is slow charging when the screen is on, and if you're actively using your phone while you're on the grid, the system automatically reduces the current to avoid overheating, so you can either put the device in airplane mode or turn it off while you're charging.

How to check that fast charging works

It is not always noticeable to see the increase in charging speed. To make sure that Quick Charge is activated, use one of the following methods:

1. via MIUI system menu

The easiest way is to see the current charging power:

1. Connect the phone to the charger.
2. Open the Settings. → Battery.
3. Slap it on the charger schedule.
4. At the top of the screen, the words “Fast Charging is Active (if the mode is on) and current power (for example, 18W)” will appear.

2.Using the Ampere app

Ampere (available on Google Play) shows the exact current and voltage values in real time.

1. Connect the charger.
2. Launch the app.
3. Look at the CHARGE value, which should be in the range of 1500-2500 mA for fast charging (for comparison, standard charging is 500-1000 mA).

If the values are lower than expected, check:

• 🔌 Adapter and cable compatibility.
• 📱 Battery temperature (in Ampere is displayed in degrees).
• 🔄 Power saving mode (turn it off in battery settings).

💡

If the Ampere is showing a current of less than 1000 mA when connected to an 18W+ adapter, then the fast charging is not activated. Check the settings or change the accessories.

How to speed up charging without harming the battery

Even with Quick Charge enabled, you can further optimize the charging process without shortening battery life.

Optimal charging conditions

• ❄️ Ambient temperature: Ideal range – 10–30°C. Avoid charging in the sun or near heat sources.
• 🛌 Airplane mode: Turn off mobile network and Wi-Fi to reduce the load on the processor. This will speed up charging by 15-20%.
• 🔕 Screen off: Display brightness and active applications consume energy. Charging with the screen off is faster.

2. MIUI settings for maximum efficiency

In the firmware MIUI there are hidden options that affect the charging speed:

1. Open the settings → Battery → Settings.
2. Turn off the optimised charging option (it limits the current to extend the battery life).
3. Activate Fast Charging over the cable (if option is available).
4. In the developer menu (Settings → For developers), disable MIUI Background Optimization.

3. Alternative methods

If standard fast charging doesn’t seem fast enough, consider the following options:

• 🔄 Partial charging: Charge your phone to 80% - this will speed up the process and prolong battery life.
• 🔋 External battery with QC 3.0: Powerbank with fast charging support (e.g. Xiaomi Mi Power Bank 3 Pro) can charge the Redmi 9 by 50% in 30-40 minutes.
• ☀️ Solar chargers: Some portable solar panels (e.g. Anker PowerPort Solar) support solar chargers QC 3.0. Suitable for hiking or traveling.

⚠️ Note: Do not use accelerated charging if the phone’s battery is already worn out (capacity below 70% of the original).This may cause the device to suddenly shut down. Check the battery status in the AccuBattery app (available on Google Play).

Frequently asked questions