Xiaomi Redmi 8, released in 2019, has proven itself as a reliable device with excellent autonomy thanks to the battery capacity of 5000 mAh. However, lithium-polymer power supplies have a limited resource of charge-discharge cycles, and after 2-3 years of active use, the capacity inevitably drops, leading to rapid discharge and unexpected shutdowns. If your phone stops holding charge or turns off at 20-30% of the battery, it’s time to think about replacing the battery.
The battery replacement process in this model has its own characteristics related to the design of the case and the location of the plumes. Unlike many modern flagships, there is no wireless charging, which greatly simplifies access to the insides after removing the back cover. Self-repair will save money on the services of the service center, but requires accuracy, the availability of special tools and strict adherence to safety when working with electronics.
Before you start, it’s important to understand that opening the case can lead to a loss of warranty if it’s still valid, although this is no longer relevant for the 2019 model. The main goal is to not damage the fragile plumes of the display and main camera module, which are located in the immediate vicinity of the battery. In this article, we will discuss in detail what tools you will need, how to safely unstick the rear panel and how to properly connect the new battery so that your Redmi 8 works again as a new one.
Tools and workplace preparation required
Replacement of the battery is not possible without appropriate tools. Use of improvised tools such as kitchen knives or needles is strongly discouraged, as there is a high risk of damage to internal components or shortening the chain. You will need a specialized kit for repairing mobile devices, which can be purchased from any radio store or ordered online.
The workspace should be well lit, preferably a table lamp with cold light to see small screws and connectors, the surface of the table should be clean, dry and preferably covered with an antistatic mat or just a clean sheet of paper, so as not to lose small details.
- 🔧 Set of screwdrivers: mandatory presence of a cross screwdriver PH00 or PH000 for the screws of the body and possibly a flat screwdriver for the careful snapping of the plumes.
- 🔥 Hair dryer or thermophen: necessary to soften the glue that holds the back cover; household hair dryer is also suitable, but you will have to warm longer.
- 🎴 Plastic cards or mediators: required to gently separate the lid from the frame without damaging the plastic and adhesive layer.
- 🧲 Magnetic mat or organizer: critical for sorting screws, as they can vary in length and thread.
Also remember to fully discharge the smartphone before work, or, conversely, charge it to 30-40% if the model allows a safe shutdown, although the standard safety is considered to discharge below 25% to avoid fire when punctured. Prepare the container in advance for recycling the old battery, as throwing it in a regular garbage can is prohibited by environmental regulations.
Diagnosis of the battery status and the choice of a new battery
Before disassembling the device, make sure that the problem lies in the physical wear of the battery, and not in the software failure or malfunction of the power controller. Xiaomi smartphones have built-in diagnostics, available through the engineering menu or a special application Security.
Visual inspection can also provide a lot of information: If the back of the smartphone has started to spontaneously move away or a gap has appeared between the frame and the screen, this is a sure sign of battery bloating. A bloated battery is dangerous: it can not be pierced, compressed or heated above 45 degrees, because there are flammable electrolytes inside.
⚠️ Warning: If you find that the battery is very swelled and pressing on the screen or back cover, remove it with utmost care.Do not try to push it back into the case - this can lead to depressurization and fire.
When choosing a new battery for the Redmi 8 (BM4C battery model), it is important to pay attention to the labeling and capacity. The original batteries have a capacity of 5000 mAh (typical) and 4900 mAh (minimum).
- 🏷️ Labeling: Look for the model code BM4C on the battery sticker, this ensures compatibility with the connector and seat.
- 🔋 Capacity: Real capacity should not be less than 4800 mAh, anything lower is a sign of defective or old element.
- 🛡️ Protection: quality batteries have a full protection fee (BMS) controller to prevent overcharging and deep discharge.
How to check the date of production of the battery?
Step-by-step: Removal of the back cover
The most important step in the repair of Xiaomi Redmi 8 is the careful removal of the rear plastic panel. It is attached around the perimeter to double-sided tape and glue. Misconduct at this stage can lead to cracks in the plastic or damage to the camera glass.
Start by removing the tray SIM-So you can use the card to keep it warm, and then you can turn on the phone and heat the back cover with a hair dryer, and you can have circular motions, and you can warm the perimeter evenly over the course of the day. 2-3 Plastic must not become hot until it is impossible to hold in your hands, the temperature is sufficient. 60-70 degree.
After heating, insert a plastic card or mediator into the junction between the frame and the lid at the bottom of the phone (near the charging socket). Carefully steer the tool along the side faces, cutting through the glue layer. Do not go more than 3-4 mm deep so as not to touch the plume of the fingerprint scanner, which is located on the back cover.
☑️ Checklist for safe autopsy
When the perimeter glue is loose, don't try to pull the lid sharply. Carefully lift the bottom corner and make sure the fingerprint scanner plume is free. The scanner plume is very thin and easily breaks when stretched. If the lid is pulled tight, warm the top near the camera module again.
Dismantling an old battery and installing a new one
Once you remove the lid, you'll have access to the insides. In Redmi 8, the battery takes up most of the space and is covered by a plastic frame that's also glued, and you need to first disconnect the battery plume from the motherboard.
Carefully unscrew the screws that hold the plastic lining over the plume connector. Using a plastic blade, unplug the battery connector. Only then can you start removing the battery itself. It's attached to powerful adhesive strips, so you can't just pull it out.
Use a thin line, dental floss, or special hood strips to extract it (if it was included with a new battery and you planted it in advance, which is unlikely). Stretching the thread under the bottom edge of the battery and cutting through the adhesive layer with sawing movements. Do not use metal objects to avoid piercing the battery.
| Parameter | Original Xiaomi | Quality copy | Cheap forgery |
|---|---|---|---|
| Capacity (typical) | 5,000 mAh | 4800-5000 mic | 3000-3500 mAh |
| Weight. | ~75g | ~70-75g | ~50-60g |
| Model code | BM4C | BM4C | BM4C (often washed away) |
| Print quality | Clear, not washed. | Good. | Blurred, finger-washed |
After removing the old battery, thoroughly clean the seat of glue residues. Degrease the frame surface with alcohol or a special cleaner. Apply a new double-sided tape (usually complete with the battery) or a special glue B-7000 to fix the new element.
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Use B-7000 glue instead of Scotch only as a last resort.Scotch makes it easier to replace the battery in the future, and the B-7000 glue hardens over time and complicates re-repair, although it holds very reliably.
Smartphone assembly and initial launch
Set the new battery into the case, pressing it tightly throughout the adhesive clutch area. Connect the battery plume to the motherboard before the characteristic click. Make sure the connector is flat and unskewed.
Then you have to check the device's performance before you finally stick the lid. Press the power button. If the screen catches fire and the phone starts loading, half the way is done. If the phone doesn't respond, try pressing the power button for 10-15 seconds or plug in the charger.
If the smartphone is on, check the charge level in the system. Sometimes the power controller needs to calibrate: discharge the phone before turning off, then charge to 100% when turned off. After successful testing, you can glue the back cover, preheat the edges and apply a new layer of glue or use a ready-made glue circuit.
⚠️ Warning: Do not stick the lid firmly until you make sure that the phone holds a charge and is stable for several hours. 1-2 an hour under light load (book) for polymerization of glue.
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Successful battery replacement is confirmed by a stable percentage of charge under load and the absence of voltage surges that were before repair.
Typical errors and security measures
Electronics repairs are always risky. One of the most common mistakes is to damage the plume of the display when the lid is not removed neatly. In Redmi 8, the display is glued to the frame, and inexperienced craftsmen often change the entire module instead of the battery because of a cracked screen.
Another common problem is the use of inappropriate tools: Metal blades can short contacts on the board, which will cause the power controller to burn, always use dielectric tools and remove static electricity from your hands before touching the board.
- ❌ Overheating: Do not heat the case with a hair dryer for too long, the insides of the phone also heat up, which can damage OLED-The screen (although Redmi 8 is on the screen) IPS, It's also sensitive to temperature, or it's a touchscreen.
- ❌ Force: Never use force. If the part doesn't work, it means you've unscrewed the wrong screw or you haven't warmed up the glue.
- ❌ Assembly order: assemble the phone in order, reverse disassembly, checking each step.
These simple rules will allow you to successfully replace the battery and extend the life of your gadget for a couple of years. Remember that accuracy and patience are the main tools of the master.