Xiaomi Redmi 8 battery replacement: a complete disassembly guide

Xiaomi’s Redmi series is well-deservedly known for its reliability and autonomy, but over time, even the most capacious battery loses its original capacity. If your Redmi 8 starts to run out quickly, turn off in the cold or show the wrong percentage of charge, it’s probably time to replace the power source. This procedure requires accuracy, but it is quite feasible at home with a minimum set of tools and patience.

Before any manipulation of the internal components of the device, you need to be aware of the risks associated with leakage of the case. The adhesive base of the rear cover of the Redmi 8 is strong enough, and a sloppy opening can lead to glass chips or damage to the plume of the fingerprint scanner. In this guide, we will discuss in detail each step of dismantling the old battery and installing a new element to minimize the likelihood of errors.

The replacement process does not require a deep knowledge of electronics, but involves working with fine parts and fragile connections. It is important to prepare a workplace with good lighting, so as not to lose tiny screws and see the state of the internal plumes. Below we will discuss the necessary tools, precautions and step-by-step algorithm of actions.

Preparation of the workplace and necessary tools

The success of battery replacement depends on the quality of training. You don't need expensive professional equipment, but a set of specialized tools is a must. The main enemy in disassembling modern smartphones is static electricity and physical strength, so all actions must be smooth and thoughtful.

To get started, you will need a heating element, since the back cover of the Redmi 8 is planted on a factory glue. You can use a special heating separator, a regular hair dryer or even an electric heating pad, but the temperature should not exceed 80-90 degrees Celsius, so as not to damage the display matrix or plastic elements of the case.

• 🛠️ Precision screwdrivers (cross-haired) P2/P00 and flat) for twisting the motherboard screws.
• 🔥 A hair dryer or heating plate to soften the adhesive layer under the back cover.
• 🎴 Plastic mediators or sucker for neat removal of the cover without scratches.
• 🧴 Isopropyl alcohol or special liquid B-7000 glue-residue.
• 🔋 New battery with labeling BM4L (original).

Special attention should be paid to the cleanness of the working surface, dust and small debris can get under the display or into the charging connectors, which will cause problems in the future, it is recommended to cover the table with an antistatic mat or just clean white paper, on which all the screws are clearly visible.

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Before starting disassembly, be sure to discharge the smartphone battery to the level of 15-20%. Working with a fully charged battery increases the risk of fire or short circuit in case of accidental damage to the body of the element.

Safety when working with lithium-ion batteries

The lithium-ion batteries used in Xiaomi smartphones contain reactive substances and are energized. Mishandling them can lead not only to damage the device, but also to injury. Understanding the physical properties of the battery is a key factor in safe replacement.

The main danger is mechanical damage to the battery housing, where if you puncture the battery shell with a sharp object or severely deform it, an instant chemical reaction can occur, releasing heat and smoke, so the use of metal blades to tamper with the battery is strictly prohibited.

⚠️ Warning: If you notice that the battery is swelling and takes up more space than the structural compartment, act with utmost care.

It's also important to keep in mind the temperature. The heating of the smartphone to peel off the lid should be local and controlled. Overheating the battery to temperatures above 100 degrees can trigger irreversible degradation processes or even thermal acceleration. If the device falls into the water before replacing, it must first be thoroughly dried, because trying to disassemble the wet phone is guaranteed to corrosion the contacts.

• 🚫 Never use sharp metal tools to tamper with the battery from the compartment.
• 🌡️ Control the heating temperature of the back cover so as not to overheat the internal components.
• 👐 Work in dry conditions, eliminating moisture on open contact boards.

If the electrolyte hits the skin, you should immediately wash the affected area with plenty of water. Although the risk is minimal in modern sealed cells, you should not neglect basic safety rules. If the battery starts to smoke, it should be placed in a non-combustible container with sand.

The process of dismantling the back panel and protecting the board

The first step in replacing the battery in Redmi 8 is to remove the back glass panel. This operation requires patience, because the adhesive layer around the body's perimeter is quite robust. SIM-cards to relieve internal stress in the construction of the body.

Warm the perimeter of the back cover with a hair dryer for 2-3 minutes. Constantly check the temperature with your finger - the glass should become warm, but not burning. After warming up, insert the suction cup into the bottom of the lid, create a vacuum and slightly pull up, while introducing a plastic mediator into the resulting gap.

We use a mediator along the perimeter, gradually cutting through the adhesive layer. Don't try to open the lid with a jerk, this can lead to cracks in the glass or tearing off the plume of the fingerprint scanner, which is glued to the inside of the lid. When the lid is separated, put it in a safe place.

Under the back cover, you'll see a plastic safety pad covering the motherboard and the plumes, which is mounted with multiple screws of different sizes, and it's recommended that you lay the screws out in the order you twisted them, or use a magnetic mat with markings, because the screw lengths may vary.

Once all screws are removed, carefully apply the plastic protection to the mediator, which will open access to the main components: the motherboard, the battery and the main camera module, and now you need to turn off the plumes to completely de-energize the device before further disassembly.

Disconnecting the plumes and removing the old battery

At this point, we come to the most critical part of the procedure: on the Redmi 8 motherboard, the battery connectors and the display are located next to each other, and you need to use a plastic blade or nail (not metal!) to snap the connector locks and disconnect the plumes.

First, the battery plume goes off, then the display and other modules, and this is a critical point: if you disconnect the display first and leave the battery connected, there is a risk of short circuits if you move carelessly, and once you turn off all the connections, you can move on to removing the battery itself.

The battery in Xiaomi Redmi 8 is also put on glue, but less aggressive than on the lid. Under the battery is often a special hood (pull-tab). If it is preserved, carefully pull it, trying to keep the tension angle parallel to the plane of the phone. If the tape is not or it is broken, use isopropyl alcohol.

⚠️ Attention: It is strictly forbidden to poke the battery with a screwdriver or knife from below.Puncture of the lithium-ion cell housing will lead to instant ignition of the electrolyte and possible explosion.

Put a thin plastic card or line under the battery and slowly cut off the glue with sawing movements, and you can slightly warm the bottom of the phone (back from the display) to soften the glue.

Once successfully removed, inspect the compartment for glue and debris residues. Clean the surface with a soft cloth soaked in alcohol. Make sure the contacts on the board are clean and not oxidized. The old battery needs to be disposed of in a special container, rather than thrown into a shared trash can.

Installation of a new battery and assembly of the device

Install the new power supply in reverse disassembly order. Before mounting, make sure that the new battery has a charge of about 40-60%. If the voltage on the contacts of the new battery is too low, the phone may not turn on immediately after assembly.

Apply a thin layer of special B-7000 glue or use pre-made adhesive strips (double-sided tape) on the battery compartment. Do not use superglue (cyanacrylate), as its vapors can settle on cameras and speakers, disabling them, and the glue itself becomes brittle and does not hold the battery.

• 🔌 Gently connect the battery plume to the motherboard before the characteristic click.
• 📱 Put the battery in the compartment, making sure it doesn't hang around or bulge out.
• 🔗 Connect the display plume and check the screen before the final assembly.

If the screen catches fire and shows loading, you can continue building. Turn off the battery again (for safety), install a plastic safety pad and twist all the screws into their places. It is important not to drag the screws, so as not to break the thread in the plastic racks of the case.

In the final step, we apply a new layer of glue or adhesive stripes around the perimeter of the back cover, let the glue dry slightly (if liquid is used) for 1-2 minutes, then gently press the cover. For better fixation, you can put the phone under the press (for example, under a stack of books) for 15-20 minutes.

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The quality of the back cover has a direct impact on the moisture protection and overall stiffness of the smartphone design. Don't skimp on adhesives when final assembly.

Primary calibration and performance check

Once the device is built, the new battery must be properly calibrated in the first place, which will help the power controller display the charge level correctly and prolong the life of the new battery. Today’s Xiaomi smartphones have built-in calibration algorithms, but manual verification will do.

Turn on the phone and wait for the operating system to fully load. Connect the original charger and charge the smartphone to 100%. After reaching full charge, leave the phone on charging for another 30-60 minutes to allow the saturation currents to level out.

Then use the phone as normal until it's fully discharged and automatically turned off. Try to turn it on again -- if it doesn't respond, it's discharged correctly. Then put the device back on charge, not turning it on, up to 100%. This cycle is preferably done 1-2 times.

During operation, pay attention to the heating of the case in the area of the camera and the bottom of the phone. Excessive heating can indicate poor contact of the plume or the defect of the battery itself, and it is also worth checking the fingerprint scanner, as during disassembly it could damage its plume.