Xiaomi’s modern portable batteries have proven to be reliable and durable devices that can recharge smartphones away from the grid. However, even the highest-quality lithium polymer cells lose their capacity over time, and electronics can fail due to voltage surges or mechanical damage. Owners often wonder how to disassemble the Xiaomi 20000 Power Bank to replace the battery or check the status of internal contacts without resorting to the services of a service center.
The process of dismantling this device requires a certain amount of precision and understanding of the design, since the manufacturer uses a single aluminum case without visible screws. This is done for aesthetics and dust protection, but it makes it much more difficult to access the insides. You will need special tools, such as thin plastic blades, a dryer to soften the adhesive and a set of precision screwdrivers. It is important to understand that opening the case automatically voids the warranty, so you only decide to do this step if you have a warranty period or complete confidence in your actions.
Before you start physically affecting a device, you need to do a thorough visual diagnosis. Often the problem is not with the batteries themselves, but with the charge controller or cable you use. If you have determined that you need an internal audit or cell replacement, prepare a workspace with good lighting. Don't forget about safety: lithium batteries do not tolerate punctures and short circuits, which can lead to ignition.
Tools and workplace preparation required
The Xiaomi Mi Power Bank 2 or earlier is assembled very tightly, and the use of inappropriate items can lead to deformation of aluminum or damage to plastic plugs. The main enemy when opened is the glue that fixes the end plastic inserts. It will require a heat source to soften it, but it is important not to overheat the device so as not to damage the chemical composition of the batteries.
You'll need a toolkit that's often called a "smartphone repair kit." It includes plastic mediators or shoulder blades that don't scratch metal or conduct current. Metal tools like knives or flat-slime screwdrivers should be used with extreme caution, and only where there's no risk of damaging the circuit board or wire insulation. Any spark inside the case can be fatal to electronics.
- 🔧 Hair dryer construction or household (to heat the edges of the case)
- 🛠 Thin plastic blades and mediators for opening
- 🔩 Precision screwdrivers (cross-hatched) PH000, PH00)
- 🧤 Dielectric gloves and antistatic mat
Special attention should be paid to space organization. All small screws and parts should be folded into separate containers with signatures, because the design can use fasteners of different lengths. Never use metal tweezers to remove batteries from the housing unless they have a dielectric coating. This rule is critical to prevent short circuits at the terminals of the batteries.
Design analysis and removal of end caps
Designably, Xiaomi's external battery is an aluminum pencil case that has plastic ends pressed on both sides, and inside it is cylindrical 18650 batteries (in older models) or flat lithium-polymer bags (in newer versions 2 and 2i) connected to control boards. Access to the interior space is only opened after careful removal of these plastic inserts, which are kept on adhesive basis and tight fit.
Start by heating the perimeter of plastic plugs. Use a hair dryer with a temperature of about 80-100 degrees Celsius, and evenly warm the junction of metal and plastic for 1-2 minutes. Don't hold the hair dryer at one point for too long so that the plastic doesn't start to melt or change color. After warming up, insert a thin plastic blade into the gap between the aluminum body and the plastic.
⚠️ Attention: Do not make excessive efforts when bending the plastic. If the plug does not respond, then the glue is not warmed enough. Repeat the heating procedure, otherwise you risk breaking the mounts. USB-Ports that are often integrated into this plastic frame.
Go around the circle, peeling the glue neatly. Once one corner is free, you can use a second mediator to fix the gap. Smoothly rock the plug, gradually increasing the amplitude until it comes out of the slots. Inside you will see a circuit board screwed to the plastic base. At this point, it is important not to pull sharply, because the circuit board can be soldered wires or it can be connected with a plume to another part of the circuit.
Removing internal fillings and accessing batteries
Removing one of the end plugs (usually starting with the one where the USB connectors are located) will open access to the fasteners. In the Mi Power Bank 20000 model, the control board is usually fixed with two or four screws. Carefully twist them using a suitable cross screwdriver. If the screws are torn or lacquered, drop a little solvent, but this is rare in Xiaomi devices.
The most important thing to do next is to remove the battery pack. Depending on the modification, the batteries can be soldered to each other and to the board, or connected through a connector. In classic models with cylindrical 18650 cells, they are often packed in shrinkage and tightly inserted into the case, you will need to carefully pull for a fee or use a plastic blade to rattle the battery pack from the bottom side.
- 🔋 Disconnect the plume or wires going to the board if they interfere with full extraction.
- 🧱 Remove the battery pack, trying not to damage the insulation against the aluminum walls
- 🔍 Inspect the insides for bloating, oxides, or traces of burns
- 🧹 Clean the case of residues of old glue and dust before reassembling
If you own a version with flat packs, they can be glued to the walls of the case or to each other, in which case extraction requires you to carefully warm the case again or use a plastic card to peel the packages off. Act slowly so that you do not pierce the battery shell with the sharp edge of the case.
☑️ Checking before disassembly
Diagnosis and replacement of food items
When the insides are removed, you can start to diagnose, first of all, visually assess the condition of the elements. Swelling cylinders or bloated packages are an obvious sign of the need to replace. Use of such elements is strictly forbidden, because they are fire-prone. If the batteries look normal, you will need a multimeter to measure the voltage on each cell.
The nominal voltage of a serviceable Li-Ion cell should be in the range from 3.0 to 4.2 Volts. If the multimeter shows values below 2.5 V, the element is likely to degrade and not hold load. Xiaomi builds often use a serial-parallel connection. This means that the elements are soldered together with nickel tape. To replace you will need a spot welding or a powerful soldering iron with flux to disconnect old cans and solder new ones.
When buying new batteries, pay attention to their size and capacity. 20000 mAh is commonly used 4 element 5000 mAh (if it is Li-Po) or 6-8 element 18650 down 3200-3500 It is important to buy batteries from proven brands such as LG, Samsung, Sony or Sanyo. Cheap Chinese counterparts often have real capacity in the market. 2-3 less than the amount claimed, which will negate all repairs.
| Parameter | Norma. | Critical condition | Action. |
|---|---|---|---|
| Voltage (Li-Ion) | 3.7. to 4.2 B | Below 2.5 V | Replacement of the element |
| Appearance | Smooth hull | Bloating, denting. | Urgent disposal |
| Temperature. | Room room | Charging heating | Checking and replacement of KZ |
⚠️ Warning: When soldering new batteries, don't overheat them. Keep the soldering iron in contact no more. 2-3 You can have the insides of the cell boiling and breaking right in your hand, use the active flux and get the contacts out quickly.
Checking the charge controller and control board
Often the problem with Power Bank failure is not the batteries, but the control board (BMS) is responsible for voltage conversion, protection against short circuit, overheating and overcharging. Carefully examine the charge under increase. Look for blackened cells, swollen capacitors or traces of oxidation from moisture.
Pay special attention to USB ports. In Xiaomi models, the 20,000 Micro-USB or USB-C connectors often slack from frequent use and fall off the board. If you see the port hanging or the contacts inside are shifted, you need to solder the connector. This requires a good soldering iron with a thin sting and, preferably, a thermo-air station for neat dismantling of the multi-pin connectors.
If the circuit board is intact visually, but the device is not working, check the fuse. It looks like a small black rectangle or a cylinder on the board. Call it with a multimeter: if the resistance is infinitely high, the fuse has burned. Its replacement can resuscitate the device, but it is important to understand the cause of the burnout (often it is a short circuit in the cable or a voltage surge in the network).
How to check the fee without batteries?
Assembly of the device and testing of performance
After successful replacement of the elements or repair of the board, the assembly stage begins: Make sure that all soldered joints are reliable and do not have solder "snots" that can cause short circuit. Carefully put the battery pack back into the aluminum housing. If you have changed the elements for new ones, you may need to use a little thermal glue or double-sided tape so that they do not hang inside, but do not block the ventilation holes (if any).
Connect the battery connector to the board (if it is detachable) or make sure the solder is properly connected. Insert the plastic plug with ports in place, pre-applying a thin layer of B-7000 or similar perimeter glue for tightness. Press the plug tightly and let the glue dry for a few hours. Don't turn the device on immediately, let the chemical processes in the glue stabilize.
The final test involves charging the power bank from the network adapter and then discharging it to the consumer (smartphone). The indicators must switch correctly: blink when charged, burn constantly at full charge and go out as the device behaves strangely (heats, sparkles, does not hold a charge), immediately stop using.
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To extend the life of new batteries in the first three cycles of charging and discharging, use them slowly: charge with a current of no more than 1A and discharge with small currents, which will help calibrate the controller and evenly activate the chemical processes in the new cells.
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High-quality assembly and use of original or certified batteries is a guarantee that your Power Bank will last for several more years without losing efficiency.