The Xiaomi Redmi 4X, released in 2017, has become a bestseller thanks to its combination of metal body and battery life. For many users, this gadget is still the main or backup device, but over time, even the best quality lithium polymer battery loses its capacity. The question of what kind of battery is used in this model becomes critical when the device begins to discharge in a couple of hours or turn off in the cold.
Owners often face confusion about labeling and specifications, as there are many copies and analogues on the market. Understanding the exact technical parameters is necessary not only to purchase the right component, but also for the safe operation of the device. In this article, we will discuss in detail the specification of the regular battery, its physical dimensions and the nuances of compatibility with other models of the Redmi line.
Technical characteristics of the full-time battery
The Redmi 4X factory trim includes a battery pack code-marked BN37, a standard designation used by Xiaomi engineers to identify compatible components. The main parameter worth looking at is a rated capacity of 4100 mAh. However, the actual power consumption may vary somewhat depending on the test conditions and voltage.
The battery’s chemical composition is classic Li-Po (lithium-polymer), which provides a relatively flat shape and the ability to accommodate in the thin metal case of the smartphone. Operating voltage is 3.85 V, and charging voltage is limited to 4.4 V. These parameters are critical for the power controller, since using a battery with a different voltage can lead to incorrect display of charge or damage to the motherboard.
💡
When buying a new battery, pay attention to the date of production - optimally, if no more than 6-8 months have passed since the release, since the chemistry inside degrades even during storage.
The physical dimensions of the battery are tailored to cover almost the entire interior area of the device, leaving minimal gaps. A tight layout requires a precise match in size when replaced, otherwise there may be problems with closing the back cover or connecting the plume.
Compatibility and differences from other models
One of the features of Xiaomi’s ecosystem is the unification of components: The BN37 battery installed in the Redmi 4X is physically and electrically compatible with a number of other devices, which makes it easier to find spare parts in the market, but requires careful selection, such as the similar battery used in the Redmi 4A models and some versions of the Redmi Note 5A.
Despite the similarities, there are nuances in the firmware of the battery controller. Xiaomi smartphones often use digital protection, which can ignore the battery with the “wrong” ID of the chip, showing an error message or refusing to charge. So when buying it is important to choose options that say “For Redmi 4X” or make sure that the model is supported.
Let’s look at the main differences from the batteries of neighboring models in the table below:
| Parameter | Redmi 4X (BN37) | Redmi 4 (BN31) | Redmi Note 4X (BN34) |
|---|---|---|---|
| Capacity | 4100mAh | 4100mAh | 4100mAh |
| Tension. | 3.85 In | 3.85 In | 3.85 In |
| Form | Rectangular (rounded) | Rectangular (rounded) | Rectangular (rounded) |
| Location of the plume | Side/bottom | Side/bottom | Side/bottom |
As the data shows, the electrical parameters may match, but the geometry of the mount and the length of the plume are often different: Trying to install a battery from the Redmi Note 4X in the Redmi 4X without checking the dimensions can lead to the connector simply not reaching the board or, conversely, will hang around, causing poor contact.
Signs of wear and the need for replacement
The first sign of a chemical element's depleted life is usually a sharp drop in its charge rate, with the device showing 40% and then turning off or showing 5% a minute later, indicating that the controller is not properly calibrating the residual capacity due to cell degradation.
The most dangerous and obvious sign is the bloating of the battery case, and as you age, the polymer bag can produce gases that inflate the battery, and it's not just a defect, it's a direct safety hazard: a damaged package can ignite if it punctures or overheats.
⚠️ Warning: If you notice that the back cover of the smartphone has begun to move away or the screen is pushed out of the frame - immediately stop using the device and remove the battery!
It's also worth considering replacing if the phone gets too hot in the camera or lower body, even when it's down. The high internal resistance of the old battery causes energy losses that convert to heat. In winter, these devices can turn off when they're out. +10°C outside, as the cold further reduces the current output.
Selection of original or quality copy
The Xiaomi component market is saturated with offerings where originality is claimed but not confirmed.The real Xiaomi BN37 battery has a high-quality build, clear laser engraving and hologram (although holograms have learned to fake very well). The weight of the original battery is about 85-90 grams; too light analogues often have a lower real capacity.
Chinese copies fall into several categories: the first are “high-quality replicas”, which may even have a chip with the correct ID, but use lower quality cells (Grade B). The second is a frank marriage with a declared capacity of 4100 mAh, which in reality is 2000-2500 mAh. The difference in price between the original and a good copy can be double, but the life of the original is 2-3 times higher.
When choosing, the following criteria should be relied on:
- 🔋 Availability of a protective board with high-quality soldering (seen on the connection connector).
- 📦 Tight packaging with QR-authentication code on Xiaomi’s website (not always for older models).
- 🏷️ Clear print of text on the battery case – blurred letters speak about artisanal production.
- 📉 Reviews about a particular seller and battery brand (e.g. Nohon, Cameron Sino, and others) are often praised for quality).
The myth of "infinite capacity"
Tools and preparation for replacement
Replacing the battery in the Redmi 4X requires care, as the smartphone has a metal body and a glued rear cover design. To work, you will need a minimum set of tools that can be purchased from any electronics store or ordered online.
First of all, a heating element is needed. This can be a special thermophene, but for one-time use, a regular household heating pad or even a heated iron (through a towel) is suitable. The heating temperature should not exceed 80-90 ° C, so as not to damage the plastic frame or display.
List of necessary tools:
- 🛠️ Thin plastic blade or mediator to open the body.
- 🔧 Cross screwdriver (usually size) PH00 or PH000) screw-cover.
- 💨 Suction cup for pulling back cover (optional, but convenient).
- 🧴 Clay. B-7000 or T-7000 for fixing the cover after replacement.
Before starting work, be sure to turn off the phone. Do not try to disassemble the device while it is on, as there is a risk of short circuit of the battery contacts, which can lead to fire. It is also recommended to discharge the battery to 20-30%, as a fully charged battery is more fire-prone in case of mechanical damage.
Step-by-step instructions for replacing the battery
The replacement process begins with heating the back cover. Put the smartphone screen down on the soft fabric and heat the lid perimeter for 2-3 minutes. The glue should soften. Carefully insert the blade into the junction between the frame and the lid, trying not to damage the fingerprint scanner plume, which is often glued to the lid or runs close to the edges.
When you take the lid off, you'll see the battery locked with a metal plate or a plastic pad that's screwed up, unscrew all the screws you see, and then you'll turn off the battery plume, and you'll do that with a plastic tool or nail, so you don't damage the connector on the board.
☑️ Checklist before assembly
Removing the old battery is the most difficult thing, as it's planted on double-sided tape. Don't use metal tools to avoid piercing the battery body! Tap the edge with a plastic card and, slowly rocking, separate the battery from the body. If it's tight, you can warm the body a little on the front side (screen up) at low temperature to soften the glue under the battery.
Install the new element, making sure it lay flat and tight. Stick new strips of tape (usually bundled with battery) plug the plume before clicking, check the phone's turn on, and only after successful launch start start start to fix the back cover. Apply a thin layer of glue B-7000 around the perimeter, press the lid and lock with rubber bands for 1-2 hours before drying.
⚠️ Warning: Never compress or puncture a lithium polymer battery. Electrolyte leakage is toxic, and contact with air can cause spontaneous combustion. If the battery is damaged, dispose of it in a special container.
💡
The B-7000 adhesive quality allows the body to be reopened without heating if necessary, but ensures that it is leakproof from dust and spray.Do not use superglue (cyanacrylate) - it destroys the plastic and makes re-opening impossible.
Calibration and first launch
Once a new battery is installed, Android may not display the charge level correctly because the controller "remembers" the parameters of the old battery. To eliminate this, you need to perform a calibration procedure. This is not a software utility, but a physical process of "training" the controller.
Completely discharge the phone before it turns off. Then charge it when it's off to 100%. After reaching 100%, hold it charging for another 1-2 hours. Then turn on the phone, check the charge, and if it drops (for example, to 98%), put it on charge again. Repeat the cycle 2-3 times.
To extend the life of a new battery, it is recommended to follow the following rules:
- 🌡️ Avoid overheating the device (do not leave it in the sun, do not play heavy games on charging).
- 🔌 Try not to drain your phone to zero regularly – the optimal range for Li-Po is from 20% to 80%.
- ❄️ Do not use the device in extreme frost without protection, the cold irreversibly reduces the capacity.
Compliance with these simple rules will allow your Redmi 4X to enjoy the autonomy for a long time.Replacing the battery is a cost-effective repair that gives the device a second life comparable to buying a new budget smartphone.