External batteries Xiaomi Mi Power Bank 2C have proven to be reliable devices with a high capacity of 20,000 mAh, but over time, even high-quality electronics require maintenance. Most often, users are faced with the need to replace lithium polymer cells, which lose their original capacity after several hundred charge-discharge cycles. Self-disassembly of the case allows you to save significantly on repair and extend the life of the gadget, if you approach the process with due care and knowledge.
The dismantling process is not trivial, as the manufacturer uses hidden fasteners and durable plastic latches to ensure the monolithic design. You will need not only a standard set of tools, but also an understanding of the principles of the power controller, so as not to damage the control board at the opening. In this article, we will look at the stages of dismantling, identify hidden screws and discuss the nuances of working with high-voltage components.
Before you start to physically affect the housing, you need to make sure that the device is completely discharged or, conversely, has a minimum charge to avoid short circuits when carelessly handling contacts. Lithium cells inside the housing are energized, and any error can lead to thermal acceleration or damage to electronics. Safety is the number one priority when working with portable energy.
Tools and workplace preparation required
To successfully perform the disassembly, you will need a specialized toolkit that will ensure the accuracy and safety of the process.Do not try to use kitchen knives or rough screwdrivers, as they can damage the plastic mounting elements or scratch the aluminum case of the Mi Power Bank 2C. Workplace preparation also plays a critical role: the surface must be clean, dry and do not conduct electric current.
Special attention should be paid to the tool for opening the case, since the plastic latches Xiaomi is made of a fairly rigid polymer that is easy to break at the wrong angle of impact. It is best to use plastic mediators or special blades to open smartphones. Metal tools are only allowed for twisting screws, but not for tweaking the covers.
- 🛠️ Precision screwdrivers (cross-haired) PH000, flat-slime)
- 🪓 Plastic blade or mediator for opening the body
- 🔥 A hair dryer or thermophen for heating adhesives (if available)
- 🔍 Loop or magnifying glass for inspection of small contacts
- 🧤 Dielectric gloves to protect against static electricity
It's important to organize the space so that the small screws don't get lost. It's recommended that you use a magnetic mat or a container with cells, marking the stages of untwisting. The screw layout may not be obvious, and if you confuse their length, you can damage the thread or penetrate the body through when you build it.
⚠️ Warning: Before starting work, be sure to disconnect all power cables and make sure there are no conductive items on the desktop that can accidentally close the contact boards.
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Use a magnetic screw stand and take photos of each stage of disassembly – this will help not to forget the order of assembly and the location of the plumes.
Design analysis and search for hidden fasteners
Xiaomi Mi Power Bank 2C is designed in a sandwich form factor, where the two halves of the case fit tightly together. At first glance, it may seem that there are no visible screws at all, but the manufacturer has hidden the fasteners under decorative linings or rubber legs. Careful visual inspection of the end faces and the bottom panel often allows you to detect hidden screws.
In most of the modifications of this model, the main screws are under the bottom rubber lining, which serves for (anti-slip) and protection against scratches. Carefully pulling the edge of the lining with a thin tool, you will find indentations. USB-Ports where additional fixing elements are sometimes located.
If the screws are not detected immediately, do not use force. The design can be designed to connect exclusively to plastic latches that require careful passage around the perimeter of the housing to undock. Using excessive force will lead to cracks in the body, which will make the device less protected from dust and moisture in the future.
The process of opening the case and dismantling the board
Once you remove all the visible screws, the most critical step is to split the halves of the body, insert the plastic blade at the junction between the top and bottom of the case, starting at the angle opposite to the USB connectors, and move slowly, feeling the resistance of the latches and gently putting them on.
The case of the Mi Power Bank 2C can be assembled tightly enough, so don’t be afraid to apply moderate force, but strictly control the depth of penetration of the tool so as not to damage the internal components. Once the perimeter is passed and all latches are snapped, you can gently open the device.
Inside, you'll see the main control board, which is secured by the screws, and the battery pack, which can be glued to the case or fixed by additional screws, and to fully remove the board, you need to disconnect the plumes or wires that go from the battery cells to the controller.
- 🔌 Disconnect the cell balancing connectors from the control board
- 🔩 Unscrew the screws fixing the circuit board to the bottom of the case
- 🧩 Carefully remove the board, monitoring the integrity of the wires
- 🔋 If necessary, remove the block of cells from the plastic bed.
When working with wires, be especially careful: they can be soldered directly to the board or connected through connectors. Sharp twitching can lead to breakage of tracks on the board or damage to the insulation of wires, which can short circuit.
⚠️ Warning: Never pull wires without making sure they aren't glued to the case or board.Adhesive locker is often used to prevent components from vibrating.
☑️ Autopsy procedures
Replacement of battery cells and diagnosis
The main reason for disassembly is often replacement of the exhausted batteries. Inside Xiaomi Mi Power Bank 2C usually installed four cylindrical elements of 18650 format. Diagnosis shows that often only one or two cells fail, but for stable operation it is recommended to change the entire kit at once.
New cells must have the same characteristics: the same capacity, internal resistance and degree of charge. Using cells with different parameters will cause the entire battery unit to fail quickly and can damage the charge controller.
The replacement process involves disconnecting the nickel tape that connects the cells together, which requires spot welding or, in extreme cases, careful soldering using a powerful soldering iron and flux to avoid overheating the lithium cell. Overheating above 80 degrees can lead to bloating or fire.
Once the new cells are installed, you need to check the voltage at the outputs and make sure that you connect to the control board correctly. An error in polarity when connecting can instantly disable the electronic circuit of the overbank, so recheck the connection circuit several times.
How to check the condition of the cells without disassembly?
Assembly of the device and verification of functionality
The assembly is done in reverse disassembly. Place the block of cells in the pad, making sure the wires are not clamped or twisted. Secure the screw control board, but don't tighten them too much so as not to damage the plastic or thread.
Before you finally snap the case, you need to do a primary test, connect the verbank to the network and check the charging indication. Then plug in the load (smartphone or lamp) and make sure the device is giving off power. If everything is working correctly, you can connect the halves of the case.
When connecting the parts of the body, make sure that all the wires and plumes are in their channels and do not protrude beyond the dimensions. Carefully press the perimeter until the characteristic click of all latches. If the screws were designed, twist them and close the decorative linings.
| Phase | Action. | Risk of error | Tool. |
|---|---|---|---|
| 1 | Removing stubs | Rubber damage | Thin needle |
| 2 | Screwing of screws | Carving failure | Screwdriver PH000 |
| 3 | Autopsy of the hull | Latch break | Plastic spatula |
| 4 | Cell replacement | Short circuit. | Point welding |
| 5 | Final assembly | Clip wires. | Hands. |
The final test involves a full charge and discharge cycle, which is necessary to calibrate the controller and check the balance of the cells, and if the device heats up very much or makes extraneous sounds during the charge, immediately stop operation.
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Quality assembly and use of original or proven 18650 cells is the key to a long and safe service of the restored superbank.
Typical errors and precautions
One of the most common mistakes is to ignore the safety rules when working with lithium batteries. Short circuit of contacts even for a split second can lead to powerful sparking and heating. Always isolate the contacts of cells that are not currently working with.
Another common mistake is losing or entanglement of screws of different lengths, screwing a long screw into a short hole can penetrate the body through or damage the internal elements, including the battery cells, and sort the fasteners during the disassembly process.
Don't try to forcibly (forcefully) insert connectors if they don't fit in orientation.Connectors inside electronics have keys to prevent improper connection, but excessive force can break the plastic guide connectors on the board.
- 🚫 Do not leave disassembled lithium cells unattended
- 🚫 Do not use damaged or swollen batteries.
- 🚫 Avoid getting moisture on open electronics
- 🚫 Do not expose the device to mechanical shocks in disassembled form
⚠️ Warning: If you notice bloating cells or the smell of electrolyte, immediately stop work, place the elements in a non-combustible container and dispose of them according to safety regulations.