The Redmi 4 series has earned a reputation for being “unkillable,” but time spares no one, not even lithium-polymer batteries. If your phone stops holding a charge, turns off 30-40% or the body is inflated, then it’s time to replace the power unit. This procedure requires care, since the adhesive base in Xiaomi holds the battery very tightly, and the plumes are located in close proximity to other components.
In this article, we will discuss the process of dismantling an old battery and installing a new one on the Redmi 4A, 4X and 4 Prime. You will need not only a new battery, but also a set of special tools, including a suction cup and a plastic blade. Ignoring safety practices can damage the display or motherboard, so carefully study each step before you start work.
Should you bring a device into service? If you have experience with small electronics and you are confident in holding a screwdriver in your hands, replacing it yourself will save you a significant amount. However, if you have never opened a gadget, be prepared for the fact that the process will take longer than indicated in the commercials. Accuracy is more important than speed.
Tools and workplace preparation required
Before you start dismantling Xiaomi Redmi 4, you need to organize a clean and well-lit space. Dust and static electricity are the main enemies of electronics, so cover the table with an antistatic mat or ordinary white paper, which will show the fallen screws. You will need a special kit for repairing smartphones, which can be purchased at electronics stores or marketplaces.
The basic toolkit includes a PH00 or PH000 size cross screwdriver, a plastic shovel mediator (a guitar mediator is also suitable, but it is less convenient) and a screen suction cup. To work with the adhesive layer holding the battery, it is critical to have a hairdryer (construction or household) and isopropyl alcohol on hand that softens the adhesive.
- 🛠️ A set of precision screwdrivers with a magnetic tip for twisting the screws of the body.
- 🔥 Hair dryer or heat cushion for heating the edges of the device and softening the glue.
- 🧪 Isopropyl alcohol or special liquid B-7000 remove adhesive residues.
- 📱 Plastic blade and suction cup for safe opening of the body without chipping.
Remember to turn off your smartphone completely before you start any manipulations. Even when you're off, the battery is under voltage, and an accidental short circuit with a metal tool can knock out the power controller. Prepare the screw folding capacity, as different Redmi models use screws of different lengths, and confusing them means damaging the thread or breaking the board.
⚠️ Warning: Never use metal tools (knife, tweezers) to tweez the battery.Puncture of a lithium polymer cell will cause an instant fire or explosion with the release of toxic smoke.
☑️ Preparation for repairs
Dismantling the back cover and protective screens
The process of disassembling Xiaomi Redmi 4 begins with the removal of the rear panel, which in most versions (except the Prime version with a metal body) is made of polycarbonate. Although plastic is less fragile than glass, it is easy to scratch or break plastic latches when handled carelessly. SIM-cards and memory cards to relieve the internal stress of the case.
Heat the perimeter of the back cover with a hair dryer. Keep the heat source 3-4 cm from the surface for 1-2 minutes. The plastic should feel warm to the touch, but not melt. After warming up, insert the suction cup into the bottom of the lid, closer to the Mi logo, and gently pull up to create a gap. Insert a plastic blade into the resulting gap and run it along the perimeter, snapping the locks.
When you take the lid off, you'll see the inside of the smartphone, and you'll see a black plastic screen covering the motherboard and the plumes, it's mounted on multiple screws around the perimeter and sometimes on double-sided tape, you'll carefully unscrew all the visible screws in order, and you'll see the plastic pad, and you'll see another layer of protection or speaker underneath that also needs to be handled carefully.
Features of the metal cover Redmi 4 Prime
Now that the insides are open, you can see the battery itself, closed with a black sticker or a plastic frame, and some board revisions may have an extra metal plate on top that covers the connectors, which you have to dismantle by twisting the screws, and be careful, because there are often display and touchscreen plumes underneath.
Disabling the plumes and retrieving the battery
The most critical step is to cut the power. Find a connector that goes from the battery to the motherboard. It's usually located at the top or center of the board and has a wide flat plume. Use a plastic blade or nail to shut down, putting the connector upwards. It's strictly forbidden to pull the wires or the plume itself, this will lead to its cliff.
After the connector is turned off, the battery is still firmly glued to the body. Xiaomi uses powerful double-sided tape around the perimeter and sometimes in the center of the cell. To extract it, use a hairdryer again: warm up the area around the battery for a period of time. 2-3 The temperature should not exceed 60-70 degrees so as not to damage LCD-reverse-screen.
To extract, use a special suction hood or, if it is not available, a thin plastic card. Gently slap the edge of the battery and slowly rock it away from the body. If you feel strong resistance, add more heat. There may be adhesive tape inside the case - it must be removed to make the new element fall flat.
- 🔋 Disconnect the battery plume from the motherboard, pulling the connector up.
- 🌡️ Warm up the battery area with a hairdryer to soften the adhesive layer.
- 🃏 Carefully tuck the edge of the battery with a plastic card and remove the element.
- 🧹 Cleanse the seat from the remnants of old glue with alcohol.
⚠️ Attention: If the battery is swelling, treat it with extreme caution. Do not press it or try to pierce the shell. A bloated battery may burst from mechanical stress.
In some cases, the glue holds so tightly that it is impossible to remove the battery intact. If you are faced with such a situation, you can carefully separate the top (where the contacts are) from the main body to access the plume, but you need to do this extremely carefully.
Installation of a new power supply and assembly
Before installing a new battery, check its voltage with a multimeter. It should be in the range of 3.7-3.8 V. If the voltage is below 3.0 V, it is advisable to “wake up” the battery with a low-current charger before final assembly. On the seat in the case, stick new strips of double-sided tape (usually come complete with a battery) or use a special glue. B-7000.
Set the battery into a niche by matching the plug with the reciprocating part on the board. Don't put the connector all the way to the end right away -- just cash it in first, make sure it's flat, and then gently press it to the characteristic click. Check if the plume is squeezed by the case or other elements. Once connected, you can do an initial check: without closing the case, press the switch button.
If the phone is on and showing charging, you can start the final assembly. Put all the metal plates and plastic screens in place with the screws twisted. Don't pull the screws over, the plastic can crack. Close the back cover, evenly pressing it around the perimeter to fix the latches.
The final step is to check the tightness and the touchscreen, swipe all corners of the screen, make sure there are no dead zones. If you used the glue to fix the lid, put the phone under the press (for example, under a stack of books) for 1-2 hours to polymerize the glue.
Comparison of battery characteristics for different models
The Redmi 4 lineup includes several modifications, and it is important not to confuse the batteries, as they can differ in size and location of the plume. Below is a table that helps to identify the right power supply for your version of the smartphone.
| Smartphone model | Type of battery | Capacity (nominal) | Location of the plume |
|---|---|---|---|
| Redmi 4A | BM4C | 3120 mAh | Up, downtown. |
| Redmi 4 (Prime) | BN41 | 4100mAh | Up, down. |
| Redmi 4X | BN41 | 4100mAh | Up, down. |
| Redmi 4 Pro | BN41 | 4100mAh | Up, down. |
Please note that the model BN41 It is one of the most common and suitable for most versions of the “four”, except for the budget version. 4A. When buying, pay attention to the presence of a hologram and QR-code on the package, as the market is oversaturated with cheap copies with an understated real capacity.
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Quality check: After installing a new battery, download an app like AccuBattery or AIDA64, which will show real capacity and wear, and if the wear shows 0% immediately after installation, and the phone holds a charge for 2 hours, you're a fake.
Primary calibration and calibration of the system
After a successful battery replacement, Android may not display the percentage of charge correctly. The system remembers an old, degraded cell and calculates the voltage incorrectly. To correct this, you need to perform a calibration procedure. This is not always necessary, but is recommended for the indicator to work accurately.
Discharge the new battery before the smartphone is completely turned off (0%). Then put the phone on charge when it is turned off and wait for 100%. After reaching full charge, keep the device on charge for another 1-2 hours. Then turn on the phone and check if the percentage of charge has fallen. If the percentage is still in place, the calibration was successful.
In some cases, you need to reset the battery statistics through the engineering menu or root rights, but for most users, one or two full-discharge cycles are enough.
⚠️ Warning: Do not leave your phone charging overnight on the first day after you have been replaced unless you are sure of the new battery.
Typical errors and troubleshooting
Even experienced wizards sometimes have problems after replacing the battery. The most common issue is that the phone turns on but says "Plug the charger" or reboots cyclically, which can mean that the connector is not fully inserted into the connector. Disassemble the device again and check the connection density.
Another problem is that the phone can't see. SIM-This indicates that when you install the battery or protective plate, the antenna plume or audio module has been compressed or damaged. Also check if you have forgotten to connect any connector, such as a touchscreen.
- 🔄 Phone reboots: Check the density of the battery connector landing.
- 🔇 No sound: Inspect the plume of the lower speaker and the main board.
- 📶 Do not catch the network: Check the contact of the antenna cable (usually gold wiring).
- 📉 Fast discharge: Perhaps a new battery's defect or system background processes.
If the battery is warmed to a idle after replacement, it is an alarm, perhaps a short circuit inside the cell or a malfunction of the charge controller on the board, in which case operation should be stopped immediately.
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A high-quality battery replacement returns 90% of its original autonomy to the smartphone, prolonging the life of the device for 1-2 years of active use.