The Xiaomi Mi Power Bank 20000 series has earned a reputation for being reliable and durable, providing multiple charging in the field. However, even the best-quality lithium polymer battery loses capacity over time or fails due to heavy use. Many users face the need to replace power cells or repair the controller, but do not know how to safely open the monolithic case of the device.
The process of dismantling this gadget requires care, since the design is made without visible screws and involves the use of thermal influence to soften the glue. In this article, we will examine in detail the stages of disassembly of the popular model Mi Power Bank 2 Pro 20000, the necessary tools and precautions.
It is worth noting that self-interference with the device will void the warranty if it has not expired. However, for devices that have already served their life, this is the only way to extend the life of the gadget without buying a new one. Before starting work, make sure that you have basic electronics skills and understand the risks associated with short circuits.
Preparation of the workplace and tools
You can't disassemble electronics properly without a well-organized space and specialized tools. You'll need a clean desk with good lighting to see the fine details and not lose the tiny screws. The main tool will be a hair dryer or a professional thermo-air soldering station, which is necessary to heat the adhesive layer.
In addition to the heating element, you will need a set of plastic mediators or thin metal blades to snap the case. Metal tools should be used with extreme caution to avoid damaging the polymer elements inside. Also prepare tweezers with thin curved ends to work with plumes and small connectors.
⚠️ Attention: Using knives or sharp objects to open the case can cause battery puncture and fire, so act as delicately as possible.
To reverse assemble and fix the elements, you will need a thin double-sided tape or a special glue B-7000. Be sure to prepare the screw folding container, as their sizes may vary, and it is critical to avoid mixing up the installation sites. If you have a multimeter, it will help check the voltage on the contacts before you start manipulating.
- 🔧 A hair dryer or thermophen to heat glue.
- 🛠️ Set of screwdrivers (cross-crosses) P2, P5 screw-on).
- 📏 Plastic blades and mediators for opening.
- 🧲 Tweezers and containers for fasteners.
- 🔋 Multimeter for diagnosing food chains.
☑️ Checking disassembly readiness
Design and access points analysis
Xiaomi Mi Power Bank 2 20000 is made in all-metal case, which gives it a premium look, but significantly complicates the repair process. Unlike plastic analogues, there are no latches around the perimeter, and the entire structure is supported by a powerful adhesive layer and two screws hidden under plugs. USB-Understanding this architecture is the key to successful undamaged disassembly.
The first step is to look carefully at the ends of the device, and one of the narrow faces is the USB Type-A connectors and the Micro-USB or USB-C input port, depending on the revision, and it's under the rubber or plastic plugs of these ports that the locking screws that need to be unscrewed first are hidden.
Once the screws are removed, the main task is to separate the two halves of the body, which are tightly pressed against each other. The glue used by the manufacturer is designed for high loads, so simple effort is not enough. It requires uniform heating of the device perimeter to a temperature of about 60-70 degrees Celsius to soften the adhesive layer.
| Component | Location. | Type of attachment | Tool. |
|---|---|---|---|
| Body screws | Ends (under ports) | P2/P5 screws | Screwdriver. |
| Sticky layer | |||
| Controller's fee | |||
| Battery |
Why doesn't the body open right away?
Heating and opening process
Heating the case is the most important step, requiring temperature control. Turn on the dryer at medium power and start evenly warming one of the long faces of the device, constantly moving the air flow so as not to overheat one point. Xiaomi's metal body conducts heat quickly, so after 2-3 minutes you can try gently inserting a plastic blade into the joint.
If you feel resistance, don't use force, add a little more heat. Move around the perimeter, gradually injecting the blade deeper and cutting the adhesive layer. It's important not to damage the plume of the power button, which can be glued to the inside of the case or board.
⚠️ Warning: Excessive heating above 80 degrees can damage the structure of lithium cells inside, so keep your finger on the case - if it gets hot to hold, stop heating.
When the case starts to diverge, use a few mediators to insert them into the gap so that the glue doesn't get caught back. Act slowly, listening to the sounds: the characteristic crackling of the glue is a good sign, and the sound of the tearing plastic signals an error, and your goal is to completely separate the metal frame from the central plastic platform.
- 🌡️ Warm up the edges evenly, without holding the hair dryer in one place.
- 👐 Check the temperature with your hand so that the battery does not overheat.
- 🔪 Insert the shoulder blade at an angle 30-45 degree-plane.
- 🛑 When resisting, add heat, not force.
Disabling plumes and retrieving boards
When you successfully remove the top cover, you'll see the inner part of the superbank, and you'll see a circuit board with a charge controller, ports and an on button, and the first thing you need to do is turn off the battery from the board to shut down the system and avoid short circuits in further manipulation.
The battery connector is usually on the side, and it's a white connector that you have to pull upwards behind the plastic ears, not the wires, and you can't pull the wires, because you're going to break them at the base, and you can turn the screws off, and you can pull the screws that hold the board to the plastic base.
On some Mi Power Bank models, the power button is connected to the board with a thin plume that also requires careful shutdown, which requires bending the fixing plastic tongue of the connector (if any) and smoothly pulling out the plume. The capacitors on the board can retain charge for a while, so avoid touching the contacts with your fingers.
Now the board is completely free and can be put aside, and you can have access to two or three rectangular batteries attached to double-sided tape, and you can move on to the next step, which is replacing or diagnosing the batteries.
Replacement of elements of power and diagnosis
Inside the case Xiaomi 20000 usually installed two or three elements of the 18650 format or flat lithium-polymer packages of high capacity. If the device stopped holding charge, the problem is often the degradation of these cells. To replace you need to carefully unstick the locking tape and remove the old elements.
New batteries should have identical voltage characteristics (3.7V) and similar capacity. When installing new cells, it is important to observe polarity when connecting wires to the contact group if you change them with soldering. If you use ready-made assemblies with connectors, just connect them to the appropriate contacts on the board.
⚠️ Warning: Never connect the plus and minus of the battery directly - this will cause instant heating, sparking and possible explosion of the element.
Before final assembly, it is recommended to conduct an initial multimeter voltage test: the normal voltage of a fully charged element is about 4.2V, and the discharged one is not lower than 3.0V. If the voltage is below 2.5V, the cell is considered deeply discharged and requires special recovery or disposal.
- 🔋 Use only food from proven brands (Samsung, LG, Sony).
- ⚡ Check the voltage of each cell before installing it in the housing.
- 🧶 Lock new batteries with new double-sided tape.
- 🔌 Check the contact density of the connectors before switching on.
💡
To increase the life of a new battery, avoid a full discharge of zero and do not leave the device in the cold.
Assembly of the device and check of performance
The final step is to assemble the device in reverse order, make sure all the wires are stacked in their channels and not clamped by the body, apply a thin layer of new glue or bilateral tape around the perimeter of the plastic substrate before installing the metal cover, combine the port connectors with holes in the case.
Carefully press the halves of the body and lock them with rubber bands or clips for 15-20 minutes before the initial grasp of the glue. After that, screw the screws into the end holes and cover them with plugs. Connect the overbank to the charger and check the charging indication.
If the lights caught fire and the device started charging and also gives power to the connected smartphone, the repair was successful. The charge controller must automatically identify new capacities and calibrate after the first full charge-discharge cycle.
💡
The successful calibration of the controller occurs after 1-2 full cycles of charging and discharging the new battery.
If you don't react, check the integrity of the plumes and the reliability of the connectors. Sometimes you need to re-disassemble to correct minor defects in the assembly. Don't rush to shut the case until you're sure the system is working.