Xiaomi’s Redmi Note series is well-deservedly considered one of the most popular devices on the market due to its excellent price-performance ratio. However, even the most reliable lithium-ion batteries lose their capacity over time, leading to rapid discharge and sudden phone shutdowns. If your device is several years old, self-replacement of the battery can be a cost-effective solution that allows you to extend the life of the gadget without going to the service center.
The process of disassembling the Xiaomi Redmi Note 8 requires a certain accuracy and the presence of specific tools, since the body of the device is fastened with adhesive composition, and the internal layout is quite dense. Unlike older models, you can not just remove the back cover without damaging it, so you need to prepare the workplace and all the necessary tools in advance. In this article, we will discuss each step of the work, paying special attention to safety measures and the nuances of disconnecting the plumes.
Diagnosis of battery status and preparation of tools
Before you start physically interfering with the design of a smartphone, you need to make sure that the problem lies in the wear of the battery. Often users confuse software failures or background processes with a “dead” battery. For initial verification, you can use built-in diagnostic tools or third-party utilities, such as AccuBattery, which will show the real capacity compared to the declared factory.
If the diagnostics confirm critical wear, you should assemble tools, you will need not only a standard cross screwdriver, but also special suction cups, mediators and tweezers, and the absence of the right tool can lead to damage to the body or, worse, to a puncture of the battery, which is categorically unacceptable.
To successfully complete the operation, you will need:
- 🔧 Precision screwdriver set (PH00, PH000)
- 🔥 A hair dryer or heating platform for softening glue
- 📱 Plastic mediators and sucker
- 🔋 New battery labeled BN46
- 🧴 Isopropyl alcohol and glue B-7000 (optionally)
Make sure the workspace is well lit and all the small parts are folded into separate containers so as not to lose the screws of different lengths.It is also crucial to completely discharge the device before work begins, or, conversely, leave a charge of about 25-30% if the model allows you to work safely at this level, although standard safety practice requires minimizing the charge in the battery before dismantling.
Rear cover removal process
The most difficult step for beginners is to carefully remove the glass back panel, which is glued around the perimeter. The heating should be done evenly, avoiding overheating of individual zones, especially in the area of the chamber where the sensitive optical modules are located. The heating temperature should not exceed 80-90 degrees Celsius, otherwise the glass can crack from thermal shock.
After you've warmed up the body perimeter for 2-3 minutes, attach a suction cup to the bottom of the back cover and pull up slightly, creating a gap. Insert a plastic mediator into the resulting gap and start driving it along the faces, cutting the glue layer. The movements should be smooth, without sharp jerks, so as not to damage the plume of the fingerprint scanner that passes under the glass.
⚠️ Warning: Do not enter the tool too deep in the top of the smartphone, where the main plume of the display connection and the motherboard are located. Damage to this plume will cause the touchscreen or the display as a whole to malfunction.
When the adhesive layer is passed around the perimeter, gently lift the lid and put it in a safe place. It is recommended to immediately clean the residues of the old adhesive from the frame of the case, so that the new battery or lid fits tightly, use a soft fabric soaked in isopropyl alcohol, which quickly evaporates and leaves no traces.
Disabling the plumes and removing the protective plate
Once you remove the back cover, you'll see the inside of the device, covered by a plastic protective plate, and this plate is fixed by a lot of screws of different calibers, so it's important to remember or photograph the location of each screw before you unscrew it, and if you mix up the screws of different lengths, you can damage the thread or break through the board.
When you take the protection off, you'll see the battery at the top and the motherboard, and the first thing you need to do is to disconnect the battery connector from the board, and you need to do this with a plastic blade or a nail, avoiding the use of metal tools that can cause short circuits on the board contacts.
Sequence of action when disconnected:
- 📸 Turn off the main camera plume
- 🔋 Disconnect the battery connector
- 📡 Remove the antenna plume (if it interferes with access)
- 💡 Turn off the button lighting and display plume
Once all communications are turned off, you can unscrew the screws that hold the battery itself. In the Redmi Note 8, the battery is also planted on glue, but access to it is opened after removing the upper plastic bezel. Be extremely careful when working in the immediate vicinity of the motherboard.
Removing the old battery and installing a new one
Dismantling the battery itself is a process that requires patience. The adhesive layer under the power cell is quite powerful, and trying to pull it by force behind the tongue (if it is preserved) or beyond the edges can lead to deformation of the body or, worse, damage to the battery. Lithium-ion cells are sensitive to mechanical stress, and any puncture causes an instant chemical reaction with the release of heat and smoke.
To safely extract, reheat the area around the battery with a hair dryer and use special suction hoods or plastic cards. If the hood is missing, you can use a thin line or dental floss, passing it under the battery and moving from side to side, cutting the glue, this method is considered the safest for the integrity of the element.
⚠️ Note: It is strictly forbidden to use metal blades or knives to tamper with the battery. Metal can close contacts inside the element or damage its shell, which will lead to fire.
The new BN46 battery should be checked with a multimeter before installation for voltage. If the voltage is below 3.7V, the battery may need to be "rocked" or defective. Set the new battery in the seat, making sure the connector matches the connector on the board, and press it slightly for primary fixation.
Assembly of the device and check of performance
The assembly is done in reverse disassembly, first of all, connect the battery plume to the motherboard, then you can put the top plastic protection in place and twist all the screws, remember to return to the place antenna contact, which is often forgotten, which eventually leads to poor reception of the network.
The back cover should be cleaned of old glue and degreased before installation. For reliable fixation, you can use a special glue B-7000 or double-sided tape designed for electronics. Apply the glue in a thin layer around the perimeter, avoiding contact with cameras and speakers.
☑️ Final assembly check
After the assembly is complete, don't rush to turn on the device. 15-20 Then plug in the charger and watch the charge indicator. If the phone responds to the charger and the screen lights up, the operation was successful.
Calibration of the new battery
After installing a new battery, the Android operating system may not correctly display the percentage of charge, since the power controller has not yet “acquainted” with the new element. To work correctly, you need to conduct a calibration procedure that will allow the system to correctly determine the capacity and charge levels.
Calibration process is simple: discharge the phone to completely turn off (0%), then put it on charge when off to 100%. After reaching full charge, keep the device on charge for another 1-2 hours. This procedure is recommended to repeat 2-3 times for the best result.
Secrets of longevity battery
Modern power controllers in Xiaomi are smart enough and often calibrate themselves over several charge-discharge cycles, but the manual procedure will speed up this process and eliminate possible glitches in displaying statistics.
| Parameter | Old battery | New battery (Original) | New battery (Copy) |
|---|---|---|---|
| Capacity | Less than 3,000 mAh | 4,000 mAh | Claimed 4,000, real 3200 |
| Voltas | Unstable. | Stable 3.85V | Power surges |
| Term of service | 1-2 years | 2-3 years | 6-12 months |
| Heating. | Strong under load. | Moderate. | critical |
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When buying a new battery, pay attention to QR-Original Xiaomi elements are clearly marked and checked on the official website of the manufacturer by code.
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A quality battery replacement returns the smartphone 90% of its original autonomy, making buying a new device so far unnecessary.