Declining smartphone autonomy is an inevitable step in the life of any active user of gadgets. If your Xiaomi Redmi Note 9 began to run out in a few hours or suddenly shut down at 20% charge, this is a sure sign that the life of the lithium-ion battery is coming to an end.
Many owners are afraid to open the case for fear of damaging fragile plumes or leakproofing. However, with a minimum set of tools and safety, this procedure can be performed at home. It is important to understand that the process requires care, since the back cover is glued to a special glue, and the internal components are located quite tightly.
In this article, we will take a look at every step of the way, from the workspace preparation to the calibration of the new battery. You will learn what tools are needed, how to safely unplug the back panel and what to look for when connecting the plumes. The nominal capacity of the original battery for the Redmi Note 9 is 5020 mAh, and this is the indicator that should be guided when choosing components.
Diagnosis of the battery condition and selection of components
Before you start disassembling, make sure that the problem is the physical wear of the battery, not the software failure. First, check the usage statistics in the Settings → Battery and Performance menu. If the discharge schedule looks smooth, but the phone turns off abruptly, this confirms the need for replacement. Also worth paying attention to the appearance of the device: bloating the back cover or screen is a critical signal that requires immediate intervention.
The choice of a new battery is a key factor in the longevity of the repair. The market is saturated with low-quality copies that can not only quickly degrade but also damage the power controller. The original batteries are labeled BN46, which corresponds to the Redmi Note 9 model. When buying, pay attention to the availability of holograms, the quality of font printing and the date of production.
⚠️ Warning: Never buy batteries without packaging or with damaged packaging.The absence of protective transport film on contacts may indicate improper storage or restoration of an old battery.
There are several categories of batteries: originals (OEM), qualitative (OEM-quality) and cheap copies: the first two options will ensure stable operation during the 2-3 Cheap analogues often have a real capacity half the declared capacity and can overheat when charging.
Tools and workplace preparation required
Replacing the battery properly is impossible without the right tools; using scissors, knives or needles can cause permanent damage to the body and internal components; you will need a special smartphone repair kit that can be purchased from any electronics store or ordered online. Workplace preparation also plays an important role: the table should be well lit and the surface protected from static electricity.
To successfully complete the task, you will need the following tools:
- 🔧 Heating element: hair dryer (construction or household) or special heating pad for softening glue.
- 📱 Suction: for gently pulling back cover after heating.
- 🎸 Mediators and plastic blades: for clipping and separation of layers without scratches.
- 🪛 Screwdriver kit: a Phillips #00 cross screwdriver and possibly a triangular bit must be available.
- 🧴 Clay. B-7000 or T-7000: for sealing the body after completion of work.
- 🧲 Magnetic mat or organizer: for sorting screws, so as not to confuse them when assembling.
Special attention should be paid to safety. Lithium-ion batteries are sensitive to punctures and short circuits. Work in a well-ventilated room and keep a fire extinguisher or sand tank on hand in case of fire (although the probability of this with careful operation is minimal).
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Use a magnetic mat or a piece of paper with sectors drawn to lay out the screws in order of their extraction, which will save you a lot of time when you build and prevent the use of long screws in short holes.
The process of disassembling the case Xiaomi Redmi Note 9
The first step is the extraction SIM-This is done before the heating starts, so that the internal machinery is not damaged and the air is released, and you can use the key that comes with the kit or the clip by pressing the hole on the bottom of the device, and then you can start heating the back cover.
Heat the perimeter of the back evenly, keeping the hair dryer at a distance of 3-5 cm from the surface. The heating time is about 2-3 minutes. Do not overheat the central part of the phone, where the processor and battery are located. You can check the readiness of the glue by trying to slightly turn the suction cup on the surface of the glass: if it slides, then the glue has softened.
Stick a suction cup to the bottom of the back cover, pull it back a little bit, create a gap, and insert a plastic mediator into it. Stick the instrument along the perimeter, gradually releasing the glue. Be careful about the camera module and the fingerprint scanner, because there may be plumes going through. Don't put too much effort into it, move progressively.
⚠️ Attention: The Redmi Note 9's back cover is made of glass, and if it's not opened or overheated, it can crack, and if the glass is broken, carefully collect the pieces with tape so they don't get inside the device, and replace the cover with a new one.
Once you remove the lid, you'll have access to the insides, and the next step is to dismantle the plastic shield that covers the motherboard and the plumes, which is usually mounted on a lot of screws around the perimeter and in the center, unscrew all the visible screws using a cross screwdriver, and carefully remove the panel by putting it on a shoulder blade.
Dismantling the old battery and installing a new one
Once the safety panel is removed, you need to disconnect the battery plume from the motherboard, which is a critical step that shuts down the device and prevents short circuits. Carefully bend the connector with a plastic blade, trying not to damage the connector itself, and then you can proceed to remove the battery itself.
The battery in Redmi Note 9 is glued to the frame of the case on double-sided tape. To remove it, it is recommended to use a special hood with suction cups or gently smear the battery with a plastic card / blade on the end sides. It is strictly forbidden to use metal objects that can puncture the battery body.
Clean the seat of the old glue and tape residues. Install the new battery, making sure it lies flat and does not protrude beyond the edges. Connect the plume to a characteristic click. Before final assembly, it is recommended to check the health: turn on the phone without sticking the lid. If the device is on and shows the charge, you can continue.
☑️ Pre-assembly check
Assembly of the device and sealing of the housing
The final step is to assemble and restore the leakage. Apply a thin layer of B-7000 or T-7000 glue around the perimeter of the frame of the case. Avoid getting glue on the camera, speaker and internal contacts. Let the glue dry slightly for 1-2 minutes so that it becomes less fluid but remains sticky.
Put the plastic shield back in place and twist all the screws. Make sure that no screw is left out. Then gently apply the back cover, combining all the holes and faces. Tightly press the lid around the perimeter. For better fixation, you can use stationery rubber bands, wearing them cross-over to the case for 15-20 minutes until the glue is completely polymerized.
Once assembled, wipe the body of the glue residue. If the glue has come out, it can be gently removed with a finger or a dry wipe until it has frozen permanently. Turn on the phone and perform a primary calibration: discharge the device to 0% and then charge to 100% when turned off.
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And quality sealing is not only about protecting against dust, it's also about preventing the lid from peeling off in your pocket. 2-3 pre-existence.
Table of comparison of characteristics of batteries
When choosing a new battery, it is important to understand the difference between the original parts and the analogues. Below is a table that will help you navigate the main parameters and differences.
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