Xiaomi Redmi 3S, launched back in 2016, has proven to be a long-lived budget smartphone. However, even the most reliable lithium-polymer batteries tend to wear out over time, losing capacity and the ability to hold a charge. If your device runs out in a couple of hours or suddenly shuts down at 30% charge, this is a sure sign that it is time to replace the power unit.
The battery replacement process in this model differs from many modern gadgets by the lack of adhesive base, which greatly simplifies the procedure for a home craftsman. You do not need chemical solvents or a hair dryer to peel off the battery, since it is fixed mechanically. The main difficulty is to carefully dismantle the back cover and properly handle the plumes so as not to damage the fragile connections.
Before starting the disassembly, you need to make sure the diagnosis is correct and prepare the workplace. The nominal capacity of the original BM32 battery is 4100 mAh, and if the actual capacity has fallen below 2000 mAh, replacement is the only effective solution. In this article, we will discuss in detail each step, from tool selection to calibration of the new battery.
Diagnosis and selection of components
Before buying a new battery, you should carefully diagnose the current state of the power system. Often users confuse software failures of the charge controller with the physical degradation of the chemical element. To begin, check the usage statistics in the Settings → Battery menu, noting sharp spikes in percentages or abnormally high consumption by background processes.
If the software reset didn't work, it's worth assessing the physical condition. Battery bloating is a critical sign that requires immediate intervention, as using a bloated battery can damage the screen or even cause fire. On the Redmi 3S, the bloated battery often lifts the back cover, making the gap between the frame and the plastic visible to the naked eye.
When choosing a new battery, it is important to pay attention to the label and manufacturer. The market is full of low-quality copies that can not only fail quickly, but also harm the motherboard power controller. The original or quality analogue (for example, Nohon or Cameron Sino) will cost more, but will provide the declared life of the work.
- 🔋 Original battery with marking BM32 The Mi logo is the best choice for maintaining autonomy.
- 🛡️ Quality third-party brands (Nohon, Deji) often have overheating protection and honest capacity.
- ⚠️ Cheap copies without a brand can have real capacity in 2-3 lesser.
Pay attention to the production date, if it is listed on the package. Lithium batteries age even when lying in storage, so buying a "fresh" battery is preferable. You should not chase a record capacity of 5000+ mAh in the Redmi 3S case format - it is physically impossible to fit such a charge into a standard volume without changing the chemistry or thickness, which will lead to problems with closing the lid.
Tools and training required
Getting the right tools and the right tools is half the success of the whole operation. The Xiaomi Redmi 3S disassembly doesn't require complex industrial equipment, but using the wrong items like knives or needles can damage the case or, worse, puncture the battery.
First of all, you'll need a suction cup to gently remove the back cover. If you don't have a special suction cup, you can use a quality window washing suction cup or even a tight tape twisted into a loop, but the risk of damaging the plastic in this case increases. To unscrew the screws, you will need a PH00 or PH000 size cross screwdriver, because the screws in Xiaomi are very small.
⚠️ Warning: Be sure to turn off your smartphone before work begins!Attempting to disconnect the battery plume when the device is on can short-circuit and cause the power controller on the motherboard to fail.
A plastic spatula or mediator is ideal for working with internal components. Metal tools are not recommended, as they can easily damage the insulation of plumes or leave scratches on the inner walls of the case. Also prepare a container with a magnetic lid or just a small container so as not to lose tiny screws that tend to fly around the table.
☑️ Preparation for battery replacement
You have good lighting. There are lots of small, dark gray-colored plumes inside the case that are not visible in dim light, and if you have tweezers with curved ends, that's a great addition to extracting screws from deep wells, although Redmi 3S is a good option.
Rear cover removal process
The Redmi 3S back cover is made of plastic and is perimeter-mounted on plastic latches. Unlike today's glued monoblocks, there's no need to heat the edge of the body with a hair dryer, which significantly reduces the risk of internal components overheating or plastic deformation.
Find a small technological groove at the bottom of the smartphone, next to the charging connector, and that's where you put a suction cup or a thin plastic card, and if you're using a suction cup, press it tightly to the center of the bottom of the lid, pull it upwards, create a gap, and insert a mediator or a spatula into the slit.
Then you have to run the tool along the perimeter of the device, snapping the locks. The movements should be sliding, directed inwards, so as not to break the outer edge of the frame. Pay special attention to the corners and areas around the camera where the latches can sit tighter.
- 🔓 Start dismantling strictly from the bottom, where the connector is located. USB.
- 🔄 Move around in a circle, gradually freeing the sides without pulling the lid sharply.
- 💡 Listen to clicks – each sound means a snapped fixator.
Once you've walked around the perimeter, the lid should be easy to remove. Don't use excessive force: if the lid isn't removed, there's an unconnected latch somewhere. Repeat the tool in the problem area. Put the lid off to a safe place, away from the edge of the table.
Disassembly of the internal module
When you take the back off, you'll have access to the insides of your smartphone, and you'll immediately notice a massive battery that covers almost the entire area, and a metal frame screen that covers the motherboard. Unlike many other models, the battery isn't glued to the insides of the smartphone, but it's locked in a plastic frame and screws, making it a technically simple task to replace.
The first thing you need to do is unscrew all the visible screws that attach the bottom plastic bar and the metal screen over the motherboard, and they're usually around. 10-12 They can be of different lengths, so it's critical to remember or record on a circuit which screw was twisted from where. Long screws screwed into short holes can damage the board through.
Once you remove the screws, carefully remove the bottom plastic bar that holds the speaker, then move to the metal screen, and you have to put a plastic blade around the camera or connectors, and remove it, and underneath it are the display plumes and the battery connectors.
⚠️ Warning: The metal screen has thin tongues that are easy to bend. Remove it evenly, without skewing, so as not to deform the metal.
Now that the components are open, you can see the battery connector, which is located at the top of the board, next to the plug of the display. Before you touch any connectors, make sure you remove static electricity by touching a grounded metal object, such as a heating battery.
Design nuances of Redmi 3S
Removing the old battery and installing a new battery
The most important moment is to disconnect the battery plume._connector_ It's a little bit deep, and it's hard to get to it with your fingers. Use a plastic blade or dielectric tweezers to gently pull the connector upwards.
Once the plume is turned off, the battery can be removed. As mentioned earlier, in the Xiaomi Redmi 3S, it is not glued. It is maintained by a tight fit in the frame and the pressure of the back cover. Just take the battery by the edges (trying not to push the center) and remove it from the case. If it sits very tight, you can slightly sway it from side to side.
The new battery is installed in reverse order, insert the battery into the compartment, making sure it is flat and not skewed. The plume should look towards the connector on the board. Connect the connector to the characteristic click, making sure that it entered smoothly and completely.
Take your time to twist the screws right away. Before the final assembly, it is recommended to check the device's health. Press the power button. If the screen catches fire and the phone starts loading, you did everything right. If there is no reaction, double-check the connection of the plume: it may not be fully inserted.
| Parameter | Original BM32 | Cheap copy | Quality analogue |
|---|---|---|---|
| Capacity | 4100mAh | 2000-2500 mAh | 3800-4000 mAh |
| Cycle resource | 500+ cycles | 100-150 cycles | 400+ cycles |
| Protection | Complete (BMS) | Minimum | Complete (BMS) |
| Price. | Tall. | Low. | Medium |
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The right battery plume connection is key to successful replacement, and an unpressed connector will cause the phone to be either out of charge or permanently rebooted.
Final assembly and calibration
Once you make sure that the smartphone is turning on and responding to charging, you can start building. Put the motherboard's metal screen in place, make sure that all the screw holes match. Then return the bottom plastic bar and twist all the screws. Remember the screw sorting rule so that you don't damage the thread or the board.
Place the back cover starting at the top (near the camera), gently pressing the perimeter until the latches click. Make sure there are no gaps and the cover fits tightly. If you hear a crunch of plastic, stop and check if something is interfering with the installation.
After assembly, it is recommended to conduct a procedure for calibrating the new battery, which will help the Android system correctly display the percentage of charge. To do this, completely discharge the phone before turning off, then charge it when turned off to 100%. After reaching full charge, hold on charging for another 1-2 hours.
- 📉 Completely discharge the device before spontaneous shutdown.
- 🔌 Put on charging in the off state to 100%.
- ⏳ Keep it on the charger for more. 1-2 half-hour.
This procedure will help the power controller to remember the limits of the capacity of the new battery. In the first days of use, observe the behavior of the device: if the phone warms up in the area of the camera or quickly discharges, you may have come across a defective instance.
Now your Redmi 3S is back to work, and a properly installed battery will restore the device to its former autonomy and allow it to be used as a backup phone or main caller for a long time, and regular checks of the battery condition will help you to notice the degradation in the future.
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To extend the life of a new battery, try not to let the deep discharge to zero regularly and do not leave the phone on overnight charging all the time unless it supports smart charging features.