Repair of Xiaomi’s superbank with your own hands: from diagnosis to repair

Why Xiaomi Verbanks Break Down and Can They Be Fixed at Home?

Xiaomi’s power banks are some of the most popular external batteries on the market due to their value for money, but even they are not immune to breakdowns: after 1-3 years of active use, users are faced with the device stop charging, do not give out current at the output or discharge in a few minutes. 80% of the causes of malfunctions are typical and fixable without going to the service center.

The main “symptoms” of failures in models Mi Power Bank, Redmi Power Bank and Xiaomi Pro: not included (no indication when you press a button), not charged from the network/USB, It doesn't charge the phone, it discharges quickly (even without a load), it heats up or it swells up, and most of these are related to battery wear, contact oxidation, or control failures. In this article - step-by-step instructions for diagnosis and repair with a photo, as well as criteria when repairing a superbank is dangerous and cheaper to buy a new one.

Diagnosis of malfunctions: how to determine the problem

Before you disassemble the overbank, check it for obvious malfunctions.

• 🔍 Case: cracks, dents or bloating (especially dangerous - this is a sign of battery damage).
• 🔌 Ports: Oxidation or contamination of connectors USB-A, USB-C or micro-USB.
• 🔋 Indicators: whether the light bulbs are on when connected to charging or pressing a button.
• 🌡️ Heating: if the case is strongly warmed without load - this is a sign of a short circuit.

Next, test the functionality:

1. Connect the overbank to another cable and power supply (exclude the problem with the charger).
2. Try charging different devices from it (smartphone, headphones, fitness bracelet).
3. Check the input voltage with a multimeter (should be) ~5V contact USB-port when connected to the network).

If the superbank doesn't respond to charging, but the lights are on, it's more a problem with the charge controller. If it doesn't give current at the output, but it charges itself, the voltage converter is to blame. The total lack of response is usually due to a circuit break or battery cell failure.

Disassembly of Xiaomi’s Verbank: Tools and Precautions

The repairs will require:

• 🔧 Plastic spatula (mediator) or a thin screwdriver for opening the body.
• ⚡ Multimeter to check voltage on the board and battery.
• 🔥 soldering iron (power 30-40 W) with a thin sting and solder.
• 🧴 Isopropyl alcohol (for cleaning contacts).
• 🛡️ Gloves and glasses (batteries can ignite!).

⚠️ Attention: When disassembling Xiaomi overbanks, there is a high risk of damage to the battery cells. If the case is bloated or deformed, do not try to open it - this can lead to fire.

Step-by-step disassembly instructions (for example, Mi Power Bank 3 Pro 20000 mAh):

1. Remove the stickers from the case (under them there may be hidden screws).
2. Carefully tuck the plastic spatula of the seam between the upper and lower part of the body.
3. Disconnect the plume connecting the control board to the battery cells.
4. Remove the board and inspect it for blackened elements (burnt resistors, capacitors).

Xiaomi’s Superbank Boards are usually equipped with: Charge Controller (e.g., charge controller, TP4056), voltage converter (SY6974 Or similar, a protective chip and a thermistor (for temperature control). If you are not sure about your soldering skills, it is better to consult a specialist.

Top.-5 causes of failure and ways to eliminate them

Most of Xiaomi’s overbank malfunctions are due to component wear and tear or factory defects, and the most common problems and solutions are listed below.

If Xiaomi’s overbank stopped charging, but the indicators burn when connected to the network, the problem is most often in the case of a battery. USB-Clean it of dust and oxides with a toothpick and alcohol, and if that doesn't work, check the integrity of the tracks on the multimeter board.

Replacement of battery cells: step-by-step instructions

If Xiaomi's superbank is rapidly discharged or not holding a charge, it's likely that lithium-ion cells have worn out, and you can replace them yourself by matching the same capacity and size, for example, in Mi Power Bank models. 2/3 cell-driven 18650 (3.7V, 3400–3500 mAh, and in Xiaomi Pro 20000 mAh — 21700 (3.6V, 5000 mAh).

Replacement will require:

• 🔋 New cells (e.g. Samsung) INR18650-35E or LG MJ1).
• 🔥 Point welding or soldering iron with temperature control.
• 📏 Thermal shrink tube for contact isolation.
• 🔧 Multimeter for voltage testing.

⚠️ Warning: When soldering batteries do not overheat them, it can lead to an explosion.The optimum temperature of the soldering iron stinger is 250-300°C, contact time is not more than 2-3 seconds.

Step-by-step process:

1. Disconnect the old cells from the board by pre-photographing the connection scheme.
2. Seal new cells in parallel (to increase capacity) or sequentially (to increase voltage).
3. Check the voltage at the output with a multimeter (should correspond to the nominal value, for example, 3.7V single-cell).
4. Isolate the contacts with a shrink tube.
5. Assemble the case, making sure that the cells do not touch the metal parts.

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Before soldering new cells, level their voltage with a charger TP4056. The difference is more 0.1V between cells can lead to imbalance and shortened service life.

Control Board Repair: soldering and replacement of elements

If Xiaomi's overbank doesn't turn on or charge, but the battery cells are working (checked by a multimeter), the problem is the control board.

• 🔌 Charge controller (TP4056, BQ24072 etc.).
• ⚡ Voltage converter (SY6974, MP2307).
• 🔥 Fuse (often burns with a short circuit).
• 📉 Resistors and capacitors (may turn black or swell).

For diagnosis:

1. Call the chain with a multimeter in mode 200Ω, track-check.
2. Check the voltage at the input of the charge controller (should be) ~5V when connected to the network).
3. Check the charge for blackened or swollen items.

If a burnt element is found (for example, TP4056), can be replaced:

1. Drink the faulty chip using the braid to remove solder.
2. Clear the contact areas with alcohol.
3. Install the new chip while observing polarity (usually marked by a dot on the case).
4. Check the work of the board by connecting it to the battery.

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If the voltage converter has burned on the board (for example, SY6974), The power bank can charge, but it can't give off the power output.

Cleaning contacts and USB-Ports: A Simple Way to Recover

Often, Xiaomi’s power banks stop charging or giving current due to oxidation of the contacts, especially for models with a Micro-USB connector (for example, Mi Power Bank 2), where the port eventually wobbles and becomes contaminated.

You'll need to clean:

• 🧼 Isopropyl alcohol (90% and higher).
• 🪥 Toothpick or plastic spatula.
• 🧵 Cotton swabs (for hard-to-reach places).

Step-by-step:

1. Disconnect the overbank from the network and discharge it to 0% (if possible).
2. Apply alcohol to a cotton swab and gently clean the contacts in USB-port.
3. For the connector USB-C Use a toothpick wrapped in cotton soaked in alcohol.
4. Blow the port with compressed air (for example, a canister for cleaning equipment).
5. Allow the device to dry for 10-15 minutes before connecting.

If the contacts are blackened or corroded, they can be cleaned with a stripe or small sandpaper (1000-1200 UAH). After cleaning, check the performance by connecting the superbank to the charging.

When repairs are inappropriate: signs of hopeless breakdowns

Not all Xiaomi overbank malfunctions can be fixed at home, and in some cases repairs will cost more than buying a new device or be dangerous to health.

• 🔥 Bloating – the battery cells have decomposed, they can not be restored.
• 💥 The smell of burning – burned critical elements of the board.
• 🔌 The cliff USB-port with board – resweetening is required, which often costs as a new overbank.
• 📉 Capacity has fallen below 30% of face value (e.g. 6,000 mAh instead of 20,000 mAh).

If the superbank has been in service for more than 3-4 years, its battery cells are likely to be worn to the limit, replacing the cells will cost 50-70% of the cost of a new device, so it is more advisable to buy a new model (for example, Xiaomi Redmi Power Bank). 30W or Baseus Blade 2).

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Xiaomi overbanks with a capacity of 10000 mAh and below are rarely subject to cost-effective repairs. Their cost on the market starts from 1000-1500 rubles, and repairs will cost 800-1200 rubles.

FAQ: Frequent questions about repairing Xiaomi's superbanks