How to change the battery Xiaomi Redmi 9 with your own hands

Xiaomi’s Redmi series is well-deservedly popular for its excellent value for money, but over time, even the most reliable battery loses its capacity. The owner of a Redmi 9 can run out of power in a couple of hours or shut down at 20 percent charge. This is a sure sign that the battery is exhausted and requires a physical replacement.

Self-replacement is not only a way to save on service center services, but also the ability to be confident in the quality of the installed part. The process requires accuracy, the availability of special tools and understanding of the internal device, in this guide we will discuss in detail all the stages of work, from diagnosis to first charging.

There's no need to be afraid of the difficulties if you're experienced with small electronics, but it's important to be aware of the risks: leakage or damage to the plumes can lead to more serious problems. In the Redmi 9, the battery is glued to the body, which requires special attention when extracting to avoid bloating or ignition. Let's get ready for the procedure.

Diagnostics and selection of a new battery

Before you start disassembling, make sure that the problem is the physical wear of the chemical element, not the software failure. Check the usage statistics in the system settings, paying attention to parasitic applications that can consume energy in the background. If there is no software cause, inspect the case for bloating back cover or gaps between the screen and the frame.

The choice of a new battery is a critical milestone. The market is full of fakes that can not only quickly fail, but also damage the motherboard power controller. The original from Xiaomi is marked BM4B and protective holograms. Avoid cheap counterparts without a name brand and protective chips.

• 🔋 The original capacity should be at least 5020 mAh (nominal) or 5000 mAh (typical).
• 🏷️ On the battery plume must be readable marking with the date of production and model.
• 🛡️ The presence of a protective film on the contacts and the integrity of the connector part are mandatory.

⚠️ Warning: Never buy batteries labeled "Original" and above 6,000 mAh in a standard case. Physical laws do not allow you to fit such energy into the dimensions of the Redmi 9 without increasing the thickness.

When buying, pay attention to the voltage, it must strictly comply with the standard 3.85V or 3.87V. Using a battery with a different voltage can lead to incorrect operation of the charge controller. Also check the status of the contacts on the plume: they must be golden in color, without oxides and darkening.

Tools and workplace preparation required

You can't have a good repair without the right tools. To replace the battery in Redmi 9, you'll need a kit that you can find in radio parts stores or order online. Don't try to use kitchen knives or needles, which is guaranteed to damage the internal components.

Organize the workspace: the table should be well lit and the surface should be clean and non-conductive. Cover the workspace with an antistatic mat or just a clean sheet of paper. All screws and small parts should be folded into a magnetic tray or on a sheet with painted sectors, so as not to lose them and remember the sequence of the assembly.

Pay special attention to heating equipment. The Redmi 9 back cover is mounted on a two-part glue that softens at about 80-90 degrees Celsius. A normal household hair dryer may not be able to cope with the task, so it is better to use a temperature-adjusted building hair dryer or a special heating pad for phones.

Disassembly of the body and dismantling of the back cover

The process of opening the case begins with turning off the device and removing the tray for SIM-This is a safety requirement, because the current in the circuit when disassembled can lead to a short circuit. USB Type-C.

After removing the screws, turn on the heating. Warm up the perimeter of the back cover evenly during the 2-3 Do not keep the hair dryer in one place for too long so as not to damage the plastic or OLED-The matrix (although in Redmi) 9 worth IPS, The plastic must be warm to the touch, but not scalding.

• 🔥 Warm up the edges around the perimeter, paying special attention to corners where the glue is usually more.
• 🔪 Carefully insert the plastic blade into the joint between the frame and the cover in the tray area SIM-map.
• ✂️ Move the shoulder blade along the perimeter, gradually cutting through the adhesive layer, without making sharp jerks.
• 👐 Use a suction cup to create a micro gap if the lid sits very tightly.

⚠️ Attention: If you feel strong resistance, don't use force. Go back to warm-up. A sharp opening can cause cracks in the glass of the back cover or damage to the plume of the fingerprint scanner, which is often glued to it.

Once the lid is successfully removed, put it in a safe place, and you will see the inside of the smartphone, closed by a plastic protective panel, and this panel is also secured with screws and glue, so you will have to repeat the warm-up and neat opening procedure, but with less effort.

Disconnecting the plumes and removing the old battery

When you take off the safety panel, you'll see the motherboard, the camera module, and at the bottom, the battery itself. The first thing you need to do is disconnect the battery plume from the motherboard, use a plastic blade or nail, gently lifting the connector up, and you're not going to use metal tools to avoid closing contacts.

The battery in Redmi 9 is mounted on double-sided tape across the entire area of contact with the frame. To remove it, you will need to apply heating again, but through the front part or carefully putting on the battery pack itself.

Clean the seat of old glue residues. Use a plastic card or spatula to scrape the large pieces, then wipe the surface with a napkin lightly soaked in alcohol or degreaser. The surface should be smooth and clean so that the new battery will lie flat and hold securely.

Installation of a new element and assembly of the device

Before installing a new battery, check its voltage with a multimeter, if possible. It should be between 3.7V and 4.2V. If the battery is discharged to zero, it is advisable to “wake” it with pulse current before installation, although modern controllers often do this automatically when first connected to the charger.

Apply a new adhesive layer. You can use special ready-made battery stickers or liquid glue B-7000. If you use liquid glue, apply it with a thin strip along the perimeter and one strip in the center, avoiding contact and camera. Let the glue dry slightly (2-3 minutes) before final fixation.

Connect the battery plume to the motherboard. You should hear or feel a slight click. Then you can plug the display plume (if it was turned off) and try to turn the device on by pressing the power button. If the screen catches fire and the phone shows the charging process, you're on the right track.

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Before you finalize all the screws, check the vibrator, speakers and microphone, which will save time for re-disassembly if some plume is inserted not to the end.

Calibration and initial setting

Once successfully replaced and assembled, the new battery must be calibrated to help the MIUI system correctly display its charge percentage and manage its power consumption correctly, without calibration, the indicator can show 100% at a real charge of 80% or drop a charge sharply at the end.

Put the phone on charge when it's off until it's 100%. After the indicator lights up green, don't turn the device off for another 1-2 hours. Then turn on the phone, wait for the boot and if the charge has dropped below 100%, reconnect the charge. Repeat the cycle until it's 100% when you turn on.

• 📉 Discharge the phone until it is completely turned off (0%).
• 🔌 Charge to 100% in the off state.
• ⏳ Hold on charging for another 2 hours after reaching 100%.
• 🔄 Repeat the cycle 2-3 time for the best result.

⚠️ Warning: Do not leave your phone unattended overnight during the first calibration cycles, especially if you used glue. B-7000 It must be completely polymerized, and the heating during charging must not be excessive.

In the process of operation, try not to bring the battery to a deep discharge regularly. Lithium-ion batteries, which are installed in the Redmi 9, best feel in the charge range from 20% to 80%.

Possible problems and solutions

Even with a careful assembly, there can be unexpected situations, such as the phone may not see charging or reboot cyclically, often due to poor plume contact, you need to reopen the case (carefully, unplug the lid) and reconnect the connector, making sure there is no dust and contamination.

If the phone turns on but quickly discharges or warms up in the area of the chamber, the power controller may have been damaged or the battery itself is factory defective, in such cases it is recommended to check the current consumption through the laboratory power supply, if possible, or consult a specialist for a diagnosis of the board.

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The quality of the adhesive composition has a direct impact on the moisture protection and durability of the battery attachment. Don't skimp on the fixing materials.

Another common problem is a Hall sensor error or a failed calibration of the proximiry sensor after disassembly. If your proximity sensor stops working (the screen does not go out during a conversation), try to wipe the top of the screen and the sensor with alcohol, and check if it is covered with a layer of glue.

Safety measures during recycling

You can't just throw an old battery in the trash, it's got chemicals that are harmful to the environment, it can react when it comes in contact with moisture, it can catch fire if it's damaged, and it's the responsibility of every electronics owner to dispose of it properly.

Hand over your spent batteries to electronics reception points or battery containers, which are often installed in large supermarkets and electronics stores. If this is not possible, isolate the contacts of the old battery with tape and store it in a non-combustible container until you hand it over.