Xiaomi Redmi Note 5, known in some regions as the Redmi Note 5 Pro, is deservedly considered one of the most reliable models in the history of the brand. However, time is not spared lithium polymer cells, and after a few years of active use, even the highest quality battery begins to lose capacity. You notice that the device discharges in a couple of hours, turns off in the cold or shows surges in charge? These are sure signs that the resource of the chemical element is exhausted.
Instead of carrying a gadget to a service center and overpaying for the work of a master, many users prefer to perform the replacement themselves. The process requires accuracy, but it is quite feasible at home with a basic set of tools. In this article, we will discuss in detail each step, from preparing the workplace to the final calibration of the new battery, so that your phone again enjoys autonomy.
Diagnosis of battery status and preparation
Before starting to disassemble, you need to 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. Often users confuse the bloating of the battery with mechanical damage to the body, but on the Redmi Note 5, the battery is hidden under a metal frame, and the bloating can lead to detachment of the screen or the appearance of glowing spots. Use special applications to monitor the health of the battery to get accurate data on the number of recharge cycles.
To do a successful operation, you'll need not only a new battery, but also a specialized tool. Cheap kits from China often contain low-quality tools that can rip off screws or damage plumes. It's better to prepare reliable tools in advance so that the process does not pause because of a broken screwdriver.
Be sure to check the following components before starting work:
- 🔋 New battery labeled BM3J (This is the model used in the Redmi Note 5).
- 🛠️ Set of screwdrivers (cross-haired) PH000 and Phillips).
- 🌡️ dryer or warmer.
- 💳 Plastic card or mediator for opening the case.
It's important to understand that even a new battery that's just been removed from the package can have a charge of about 40-60%. This is normal for lithium cell storage. Don't try to charge the phone up to 100% immediately after assembly, let the system correctly determine the parameters of the new battery.
Safety Tools and Measures at Work
Working with electronics requires strict safety rules, as components sensitive to static electricity and mechanical damage are inside the smartphone. Unlike older phones with removable batteries, the Redmi Note 5 battery is glued to the body, which requires careful handling of heating devices. Overheating can damage not only the adhesive base, but also the display matrix or plastic frame.
Special attention should be paid to the condition of the tools. Metal objects should not have sharp edges that could accidentally punctur the battery. Puncture of the lithium polymer battery will cause instant fire or a chemical reaction with the release of caustic smoke. If you notice a deformation of the old battery, you need to remove it with double caution.
⚠️ Warning: Never use metal blades or knives to tweak the battery! this can lead to short circuits and fire. Use only plastic blades or special suction cups.
The workspace should be well lit and organized. Small screws are easily lost, so it is recommended to use a magnetic mat or container with cells, where you will fold the fastener in order to dismantle, this will save you time during assembly and prevent the situation when the case is closed, there are "extra" parts.
☑️ Preparation of the workplace
Rear cover removal process
The beginning of the dismantling of Xiaomi Redmi Note 5 traditionally begins with the extraction of the tray SIM-This is a critical step, because trying to open the case with the card installed can damage the contacts of the reader or the memory card itself. After removing the tray, you need to unscrew the two screws located on the sides of the Micro-USB charging connector.
Next comes the most critical step: heating the perimeter of the body. The glue holding the back panel is strong enough that without preheating, the plastic can crack. Heat the edges of the phone evenly, without holding the hair dryer long at one point, especially in the area of the camera and speakers. The optimal heating temperature is about 80-90 degrees Celsius.
Once heated, use a suction cup or a thin plastic blade to create a small gap between the screen and the back cover. Move the card or shoulder blade along the perimeter, gradually releasing the latches. Don't try to pull the lid sharply, as it may be glued to the fingerprint scanner plume (in some modifications) or speaker.
- 🔥 Heat the body around the perimeter during 2-3 minute.
- 🪄 Insert the mediator in the upper corner and lead it down the long side.
- 🔊 Be careful at the bottom where the main speaker is located.
When all the latches are free, gently lift the back cover. If you feel resistance, check if you have forgotten to unscrew any screws or disconnect the plumes if they are attached to the lid. In the Redmi Note 5 model, the main electronics are protected by a metal plate, which will also need to be removed.
Disabling plumes and removing protection
Under the back cover is a metal frame covering the motherboard and the battery. To access the battery plume, you have to twist a lot of screws around the perimeter of this frame. The number of screws can vary depending on the revision of the board, so carefully inspect all the holes. Use a magnetic screwdriver to keep the screws from falling inside the case.
The first thing you do, once the metal shield is removed, is to disconnect the battery plume from the motherboard, which is a safety rule when repairing any electronics. Even if the phone is off, the battery contacts still have a voltage, and accidental closure of the connector can cause the power controller to fail. Bend the connector carefully using a plastic blade so that the plug on the board does not damage itself.
What to do if the plume is broken?
After the power outage, you can start removing other components if they interfere with access. In the Redmi Note 5, the battery is located under the main board in some configurations, but most often access to it is open after removing the metal cover of the speakers. Check whether the lower speaker or vibrator is blocking access to the battery, and if necessary, dismantle them by previously disconnecting the plumes.
Pay attention to the condition of the connectors, and if you see oxidized plaque or contamination on the contacts, you can clean them neatly with alcohol and a soft brush, which will improve the contact and stability of the device after assembly.
Removing the old battery and installing a new one
The hardest part of replacing is removing the old battery. In the Xiaomi Redmi Note 5, it is attached to double-sided tape, which loses its properties over time, but can hold very tightly. Don't try to pull the battery by the plume, it will come off instantly. It is also forbidden to use sharp objects to smack the battery.
The ideal option is to use special removable strips if they were included with a new battery, or gently tweaking with a plastic card on the bottom. If the battery is sitting dead, you can slightly warm the back of the case (where the battery is) with a hairdryer to soften the glue. Act slowly, gradually loosening the element.
| Parameter | Old battery | New battery (BM3J) |
|---|---|---|
| Capacity | Less than 2,500mAh (wear and tear) | 4,000mAh (nominal) |
| Tension. | 3.85V | 3.85V |
| The state of the glue | dried or swelled | Fresh double-sided scotch |
| Charge cycles | 500+ cycles | 0 cycles |
Once the old item is removed, clean the seat thoroughly of the glue residues. The surface should be smooth and clean so that the new battery lays flat and does not bulge. Stick new strips of double-sided tape onto the case or on the battery itself (depending on the configuration). Install a new battery, pressing it tightly throughout the area.
Connect the new battery plume to the motherboard before a characteristic click. Make sure the connector is up smoothly and without skewing, and then you can start to reverse assemble the metal shields and the back cover.
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Tip: Before you finally seal the case, turn on the phone and check if the battery is detectable and charging, which will avoid re-disassembly in the event of a new battery failure.
Assembly of the hull and initial launch
The Redmi Note 5 is assembled in reverse disassembly. Put all the metal screens in place and twist the screws. Don't pull the screws, especially the ones that attach the board, because it can lead to cracks in the texture. Easy enough to fix the parts to keep the pieces from hanging.
The back cover should be cleaned of old glue and degreased before it is glued, apply a new layer of glue (B-7000 or special adhesive tapes) around the perimeter, press the lid evenly and lock the phone with rubber bands for 15-20 minutes for primary glue polymerization, which will ensure that the case is tight.
After assembly, turn on the device. The first run can take longer than usual, as the system conducts the initial calibration of the new battery. Don't be afraid if the charge indicator behaves strangely in the first hours of operation.
- 📱 Turn on your phone and wait for the system to load.
- 🔌 Connect the original charger.
- 📉 Allow the phone to charge up to 100% when switched off.
Check the touchscreen and the basic functions. If everything works correctly, you can consider the replacement a success. The phone should hold the charge much longer than before.
⚠️ Warning: If the battery is warmed up in downtime or the phone is discharged quickly after the replacement, it may not be the battery that is the problem, but the power controller or software failure.
Calibration and adjustment after replacement
Once you install a new battery, it takes time for the Android system and the power controller to correctly determine the actual cell capacity, a process called calibration, and without it, you might find the phone showing 20 percent charge and suddenly turning off, or charging stops 99 percent.
To properly calibrate, run a full charge-discharge cycle. Discharge the phone to full shutdown (0%), then charge it to 100% when turned off. After reaching 100%, hold it charging for another 1-2 hours. Then turn it on and use it normally until the next full discharge. One or two of these cycles is usually enough to reset the statistics.
Also, check your energy saving settings. MIUI has aggressive algorithms that can limit the background of applications. Go to the battery settings and make sure that important applications are not constrained, which can lead to improper energy consumption.
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Proper battery calibration takes 2-3 full charge-discharge cycles and is necessary to correctly display the percentage of charge of the system.
In conclusion, regular firmware updates can also affect power consumption. Xiaomi developers often optimize power controllers in new versions of MIUI. Keep an eye out for updates and install only official versions of the software.