How to remove fast charging on Xiaomi Redmi Note 9: 5 proven ways

Xiaomi Redmi Note 9 is equipped with fast charging technology (18W), which allows you to restore battery power to 50% in just 30 minutes. However, not all users are happy with this feature: some people notice the device overheating, others want to extend the battery life, and still others simply prefer slow charging at night. In this article, we will discuss how to completely or partially turn off fast charging on the Redmi Note 9, which methods are safe and which can cause harm.

It's important to understand that the manufacturer didn't provide a direct option to deactivate fast charging in the standard settings, but there are workarounds, from using the engineering menu to hardware solutions. We've tested all methods on the Redmi Note 9 with MIUI 12-14 firmware, and we're ready to share the results. If you're not sure about what you're doing, you better study the risk section first.

Why do users want to turn off fast charging?

Quick Charge technology (or Fast Charging in Xiaomi terminology) speeds up the charging process, but has a downside. Here are the main reasons why Redmi Note 9 owners are looking for ways to turn it off:

• 🔥 Overheating of the device: with rapid charging, the body temperature can rise to 40-45°C, which is uncomfortable when used during recharging.
• 📉 Battery degradation: Lithium-polymer batteries wear out faster at high charge currents, especially if you constantly charge your smartphone on the run".
• ⚡ Unstable power: In some regions, power surges in the network can damage the charging controller when using powerful adapters.
• 😴 Night charging: Many prefer to charge your phone slowly at night so it’s 100% free of the risk of overheating by morning.

According to research, the Redmi Note 9 battery (5,020 mAh) loses up to 15-20 percent of capacity in 2 years when using fast charging intensively. For comparison, with slow charging (5W), this figure decreases to 10-12%. However, completely abandoning Quick Charge is not always rational - it all depends on your use case.

Method 1: Using a non-original adapter (the simplest method)

If you don’t need to completely turn off the fast charge in your phone, but simply charge it slower – use an adapter with less power. Redmi Note 9 will automatically limit the charge current if you plug in:

• 🔌 Charging. 5W (standard from older smartphones, for example, from the iPhone 5/6 or Samsung Galaxy S5).
• 🔌 adapter 10W (from tablets or powerbanks of medium capacity).
• 🔌 USB-Computer port/laptop (usually issued) 2.5W–5W).

This method requires no changes in the settings of the phone and is completely safe.

⚠️ Note: If you use a low quality cable with an adapter 5W, The phone may show a notification "Slow Charging" or "Charging suspended." This is normal - just replace the cable with the original or certified (for example, labeled with a label). USB-IF).

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Using a 5W adapter is the only officially approved Xiaomi way to reduce charging speed without interference with software.

Method 2: Disconnect via the engineering menu (#4636##)

On the Redmi Note 9, you can temporarily turn off fast charging via a hidden engineering menu, which works on most MIUI devices, but you need to be careful - incorrect settings can lead to crashes.

Instructions:

1. Open the Phone app and enter the combination: ##4636##.
2. In the menu that appears, select Battery Information.
3. Scroll down to AC Charge (network charging) and click on it.
4. In the Set charge current field, enter 1000 (this corresponds to 1A or ~5W).
5. Press Set and restart the phone.

After the reboot, the phone will charge more slowly. To return the standard settings, repeat the steps and enter the value of 2000 (or 0 for reset).

⚠️ Note: Changes to the engineering menu are reset after the firmware update, and some mobile operators may block access to this menu on their firmware.

Charge your phone at least 50% | Make a backup of the data |Write down the current parameters |Use the original cable-->

Method 3: Applications for charging control (AccuBattery, Battery Charge Limit)

If you need to not only slow down charging, but also limit the maximum charge level (for example, up to 80% to extend the life of the battery), third-party software will help.

• 📱 AccuBattery (free, premium): analyzes battery status and allows you to set the charge limit through notifications.
• 📱 Battery Charge Limit: Requires root: Restrictly limits the charge at the system level.

For Redmi Note 9 without root rights only AccuBattery is suitable.

1. Install the app from Google Play.
2. Go through the initial setup and wait until the application collects data about your battery (you need 2-3 charging cycles).
3. In the Charging section, activate the option to Limit Charge and set a threshold (e.g. 80%).
4. When the limit is reached, AccuBattery will send a notification to turn off charging.

The downside of this method is that it doesn't shut down fast charging completely, it only helps control the process. To completely disable Quick Charge, you'll need root or modified firmware.

Method 4: Modification of firmware (for advanced users)

If you're willing to take drastic measures, you can turn off fast charging at the firmware level, which requires unlocking the bootloader, installing a customized Recovery (TWRP) and editing system files, a method only suitable for advanced users!

Step-by-step:

1. Unlock the bootloader through the official Xiaomi tool (can take up to 7 days to wait).
2. Install TWRP Recovery for the Redmi Note 9 (Merlin model).
3. Download the file. disable_fast_charge.zip (available on forums 4PDA or XDA-Developers).
4. Reboot the phone to TWRP (hold Power + Volume up).
5. Install the downloaded zip file through the Install menu.
6. Clear the cache (Wipe → Cache) and restart the device.

After this manipulation, the fast charging will be turned off at the kernel level, and to get it back, you just need to flash the original firmware through the Mi Flash Tool.

⚠️ Warning: Incorrect firmware or editing of system files can lead to a breeze (complete failure) of the phone. OTA-Update and Xiaomi warranty will be cancelled.

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Before you run your firmware, check your Redmi Note 9 model in the settings (Settings → About Phone → Model). For the Redmi Note 9 Pro (model joyeuse), the instruction will be different!

Method 5: Hardware shutdown (for extremes)

If software methods don't work, the last resort is to physically shut down the components that charge fast, requiring disassembly of the phone and soldering, so it's not recommended without experience in electronics repair.

What can be done:

• 🔧 Solder off the resistor on the board, responsible for identifying the fast charger (you need to know the circuitry of the Redmi Note 9).
• 🔧 Replace the charging controller with an analogue without Quick Charge support (for example, from the Redmi 8 donor board).
• 🔧 Install the resistor-limiter in the power supply chain (requires accurate resistance calculation).

These are the methods used in service centers to repair phones with damaged charging controllers, and self-intervention can lead to:

• Lose the warranty.
• Damage to the motherboard.
• Fire in ration failure.

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Hardware shutting down fast charging is an irreversible process, and after such changes, the phone will not be able to charge with power above 5W even when the original adapter is connected.

Risks and consequences of shutting down fast charging

Before making a decision, consider the possible consequences:

According to tests from DXOMark’s lab, 5W-charged smartphones last 20 to 30 percent longer than fast-charging, but this only applies if other rules of use are met:

• 🛡️ Avoid full discharge (keep the charge in the range of 20–80%).
• 🌡️ Do not use your phone in temperatures below 0°C and above 35°C.
• 🔄 Calibrate the battery once every 3 months (full discharge-charge cycle).

FAQ: Frequent questions about turning off fast charging