Disassembly of Xiaomi 20800 mAh: a complete guide with photos and tips

Xiaomi Mi Power Bank 20800 mAh (PLM07ZM) is one of the most popular external chargers due to its capacity and reliability. However, over time, even such devices fail: batteries inflate, connectors break down or electronics stop working. If you are faced with the need to repair or replace components, disassembling the case is the first step.

In this article, you will find a step-by-step photo instruction, a list of necessary tools and critical warnings to help avoid damage or short circuit, and we will also analyze typical problems (for example, a charge controller failure after falling from a height of more than 1 meter) and give recommendations for diagnosing malfunctions.

⚠️ Warning: Disassembly of the Verbank will void Xiaomi's warranty and could lead to a fire if you mishandle your lithium-ion batteries.If you're unsure of your skills, contact a service center.

1. Disassembly preparation: safety tools and measures

Before you start, make sure you have everything you need, and the minimum set of tools includes:

• 🔧 Plastic mediators (or guitar mediators) – to disconnect the body without scratches.
• 🔨 Thin screwdriver with a flat sting (1-2 mm) - for slapping latches.
• 🔋 Multimeter – to check the voltage at the contacts of the battery (must be 3.7–4.2V).
• 🧤 Gloves and safety glasses – Lithium-ion batteries can ignite if damaged.
• 📸 Smartphone for photography – fix the location of parts before disassembling.

Also, prepare your workspace: a clean desk with no metal objects (exclude the risk of closure), good lighting and a fire blanket (in case of fire). If the battery is swelling, do not prick it - this can cause a chemical reaction with the release of toxic gases.

⚠️ Warning: If the body of the superbank is deformed or makes hissing sounds, don't disassemble it yourself. These are signs of an unstable chemical reaction inside the battery. Wrap the device in dense fabric and take it to the battery recycling point.

External inspection and diagnostics of malfunctions

Before you take a look at the Xiaomi 20800 mAh, identify the symptoms of the malfunction, which will help to localize the problem more precisely:

If the overbank does not turn on at all, check:

1. Integrity of the cable and power supply (try charging with another charger).
2. Voltage at the battery output by multimeter (if <2.5V, the cells are deeply discharged and may not recover).
3. The state of the fuse on the board (often burns out during voltage surges).

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If the overbank doesn't charge the phone but the lights are on, try cleaning up USB-Oxidation of contacts is a common cause of malfunction.

3. Step-by-step disassembly of the Xiaomi 20800 mAh body

The Xiaomi Mi Power Bank 20800 mAh has two plastic halves held together by latches and glue, and it requires careful handling to keep the locks intact.

Step 1. Unconnect the top cover

Insert a plastic mediator into the gap between the top and bottom of the case (start on the side opposite the body). USB-Carefully drive the mediator along the perimeter, without undue effort - the latches can crack. If the lid does not respond, slightly heat the body with a hairdryer (temperature not higher than 60).°C) to soften the glue.

Step 2: Removal of the control board

After removing the cover, you will see:

• 🔋 Battery unit (two cells 18650 connected in parallel).
• 📱 Microchip controller board TI BQ25703A (charge-driven).
• 🔌 USB-Micro-USB ports and connector for charging.

Disconnect the plumes that connect the board to the battery (use tweezers). Don't pull the wires! - they are soldered to the contacts and can come off.

Step 3: Battery removal

Cells 18650 are usually glued to the body with double-sided tape. Put a plastic shovel on them, avoiding punctures of the shell. If the battery is blown up, do not try to squeeze or puncture it - this can cause an explosion.

⚠️ Warning: If you smell burns or see traces of melting on the board during the disassembly, do not turn on the device. This is a sign of short circuit - you need to change the controller.

Typical malfunctions and their elimination

Most of the problems Xiaomi 20800 mAh related to the battery, USB-So let's look at the most common cases, the ports or the charge controller:

4.1 Damage USB-port

If the overbank does not charge the devices, but the indicators are on:

• 🔍 Check it out. USB-A ports for oxidation (clean with alcohol).
• 🔧 If the contacts are bent, straighten them gently with a needle.
• 🔨 When you break the soldering, solder the port again (use a soldering iron). 30W and soldered).

Fault of the charge controller

Symptoms: the overbank is not charging from the network, but it is charging the phone.

• 💥 Fired fuse (replace with a similar current) 3A).
• 🔋 The chip's out of order. BQ25703A (re-sweating or replacement of fees).
• 🔌 Micro-USB connector damaged (check contact integrity).

Battery degradation

If the capacity has fallen below 60 percent of the nominal capacity, the 18650 cells are to be replaced.

• 🔋 Capacity: 2000–2200 mAh (original — LG INR18650 MJ1).
• 📊 Voltage: 3.6–3.7V.
• 🔥 Maximum discharge current: >2C.

When replacing, connect the cells in parallel (plus to plus, minus to minus) and use a balancing board to equalize the voltage.

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If the battery is not turned on after the battery is replaced, check the polarity of the connection. Incorrect connection of the cells can disable the controller.

5.Poverbank assembly after repair

To assemble the device you need to reverse, taking into account several nuances:

1. Contact check: Make sure all plumes are tightly connected to the board. Oxidized contacts clean with a smooth.
2. Battery insulation: Wrap the cells 18650 with shrink tube or tape to avoid circuiting.
3. Test before final assembly: Connect the multimeter to the USB-A output and check the voltage (5V ± 0.2V).
4. Closing the case: Click the lid, starting from the side USB-If the locks are broken, use glue (see spoiler above).

After assembly, perform the charge-discharge test cycle:

1. Charge the power bank to 100%.
2. Discharge it to 0% through a load (like a phone).
3. Repeat the cycle 2-3 times to calibrate the controller.

⚠️ Warning: If the overbank warms up more than usual after assembly, immediately turn it off. This may indicate a short circuit in the chain or a malfunction of the controller.

6.Recycling of old batteries

Lithium-ion batteries 18650 can not be thrown into ordinary garbage, they contain toxic metals (cobalt, nickel) and can spontaneously ignite if damaged.

• ♻️ Hand over to the points of reception of batteries (in electronics stores or at processing plants).
• 🔋 If the battery is swollen, do not pierce it - place it in a sealed container and take it to a specialized center.
• 📦 For transportation, wrap the cells in a non-conductive material (for example, bubble film).

In Moscow and St. Petersburg, batteries are taken in:

• EcoTechnologies (networks of delivery points).
• M.Video and Eldorado (battery containers at the entrance)
• The yards under the Clean City program (special urns for hazardous waste).

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Before disposal, discharge the battery to 0% - this will reduce the risk of fire during storage.

Frequently Asked Questions (FAQ)