Power Bank Xiaomi 20000 mAh Redmi: a full guide with photos and tips

Disassembly of the external battery Xiaomi Redmi Power Bank 20000 mAh may be necessary for various reasons: from replacing the bloated battery to repairing the battery. USB-But this process requires caution, because inside the case are lithium-ion cells that, if handled improperly, can ignite or explode, and if you've never disassembled electronic devices, you'd better go to a service center. But if you decide to do it yourself, our instructions will help you avoid mistakes.

In this article, you'll find a step-by-step analysis of photos, a list of tools you need, and tips for diagnosing faults, and we'll focus on key safety issues that are often overlooked in other guides, and how to properly handle battery cell contacts. If your overbank stops holding a charge, doesn't turn on or is warming up, it might be a problem that can be solved without buying a new device.

⚠️ Warning: Xiaomi Redmi 20,000 mAh Lithium-ion batteries contain cells of the 18650 or 21700 type, which, if short-circuited or mechanically damaged, can cause a fire.Do not use metal tools to separate contacts - only plastic or wooden blades.

1. Disassembly preparation: safety tools and measures

Before you start disassembling, make sure you have everything you need. The minimum set of tools includes:

Also, prepare the workplace: the desk should be clean, without metal objects that could close contacts. Xiaomi Redmi Power Bank 20000 mAh has two types of cases: all-metal (early versions) and plastic with rubber inserts (late models).

⚠️ Warning: If the body of the verbank is swollen or deformed, do not try to disassemble it indoors - take it outside and put it in a fireproof container (for example, a metal basin with sand.

Disassembly of the hull: Step-by-step

So the hard part is to start with the top lid, and the bottom part, and in Redmi Power Bank's 20,000 mAh models, the body is either latched or glued together, and to determine the type of attachment, use your nail to the seam of the body, and if you feel a slit, it's latches, if the seam is flat, it's glue.

For latched housings:

1. Insert a plastic mediator into the gap between the upper and lower part of the case at USB-port.
2. Carefully lead the mediator along the seam, alternately snapping the mounts (starting with the corners).
3. Apply force only in the places of latches - do not press on the center of the cover, so as not to damage the board.

For adhesive housings:

• 🔥 Use a dryer at a minimum temperature (up to 60).°C) to soften the glue at the seam.
• 🧊 Alternatively, put the overbank in the freezer for 15-20 minutes (the glue will become brittle).
• 🪛 After warming up, gently lid the mediator, moving in a circle.

⚠️ Warning: If the case fails, do not apply excess force - the rations of the control board may burst inside. In extreme cases, use isopropyl alcohol 90% to dissolve the glue (use a brush over the seam).

3. Removal of control boards and battery cells

After removing the cover, you will see:

• 🔋 Two Lithium-ion Cells (usually Samsung) INR18650-35E similar).
• 📱 Microchip control board BQ25703A or similar (responsible for charge/discharge).
• 🔌 USB-Type-A and/or Type-C port(s) soldered to the board.

Procedure:

1. Disconnect the plumes that connect the board to the batteries (usually thin wires of red and black). Use a plastic spatula!
2. Turn the screws that attach the board to the body (usually 2-4 screws) PH00).
3. Carefully extract the fee, do not pull the USB-ports are fragile.
4. The cells can be glued together or fixed by a plastic holder. Don't try to unplug them unnecessarily!

📌 Tip: If you're disassembling a verbank because of bloated cells, don't puncture them or mechanically impact them -- even after being removed, they can ignite when in contact with air. Place them in a sealed container of salt or sand for disposal.

4. Diagnosis of malfunctions: what could have broken?

If the overbank does not work, first identify the symptom:

• 🔋 Does not charge itself: the problem is in the control board or Type-C connector (if there is one).
• 📱 Does not charge devices: faulty USB-port, fuse or discharge controller.
• 🔥 Heats up when charging: short circuit in cells or failure of the protection scheme.
• 💡 Blink all indicators: protection against overdischarge or KZ has worked.

For accurate diagnosis, use a multimeter:

1. Set a constant voltage measurement mode (20V DC).
2. Connect the probes to the contacts of the battery cells (red to +, black-to –).
3. Normal voltage at each cell: 3.7–4.2V. If below 2.5V — cell is deep discharged, higher 4.3V — recharged (dangerously!).

⚠️ Note: If the voltage on the cells differs more than 0.3V, They can't be connected in parallel, and that would cause current to flow and overheat, and you need to balance it with a lithium-ion battery charger.

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If the power bank doesn't turn on, but the cells are showing normal voltage, the problem is probably the control board. Try to solder it off and connect the batteries directly to the load (for example, an LED lamp) through a 10 Ohm resistor — if the current is coming, the board needs to be repaired or replaced.

5. Replacement of battery cells: selection and soldering

If the original cells fail, they can be replaced with new ones. For Xiaomi Redmi Power Bank, 20000 mAh will suit:

• 🔋 Samsung INR18650-35E (3500 mAh, 10A)
• 🔋 LG MJ1 18650 (3500 mAh, 10A)
• 🔋 Panasonic NCR18650B (3400 mAh, 6.8A)

Important: Cells must be:

1. Same model and same capacity.
2. With the same level of charge (before soldering, charge them to the same level) 3.7V).
3. With soldered nickel contacts (do not use wires - high resistance!).

Replacement process:

1. Seal old cells off the board using a soldering iron of 40–60W flux-seded.
2. Seal new cells while observing polarity (+ ce +, – ce –).
3. Isolate contacts with a shrink tube or tape.
4. Check the voltage at the output of the control board before assembly.

⚠️ Attention: Don't use acid flux, it corrodes contacts. SMD ornament.

6. repair of the management board and USB-port

If the problem is the fee, examine it for:

• 🔍 Burned elements: blackened resistors, swollen capacitors.
• 🕳️ Tracks that have broken down: often after a fall.
• 💧 Oxidized contacts: green plaque on the legs of chips.

Typical faults and repair methods:

For repairs. USB-port:

1. Drain the port with a soldering hairdryer or a soldering iron with a suction.
2. Clear the contact areas of the old solder.
3. Install a new port (e.g. Type-C female) 16pin), polarize.

📌 Advice: If there is no experience of soldering SMD-components, use low-temperature solder (for example, Sn42Bi58 melting point 138°C) - it reduces the risk of overheating fees.

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The most common reason for failure of the control board is the use of non-original chargers with a voltage higher 5V. Always check the power supply output voltage before connecting to the superbank.

7.Assemblying and testing after repair

After repair, collect the verbank in reverse order:

1. Put the control board in place, secure the screws.
2. Connect battery plumes (observe polarity!).
3. Close the case, making sure the latches are in place. If the case was glued, use cyanoacrylate adhesive (for example, "Moment Super").

Testing:

• 🔌 Connect the verbank to charging and check if the current is coming (indicators should flash).
• 📱 Connect your smartphone – it should start the discharge.
• 🔥 The heating of the body should not exceed 40-45°C in normal operation.

⚠️ Note: If the overbank does not turn on after assembly, disassemble it again and check it:

• The polarity of battery connection.
• Rations integrity on the board.
• Short circuit (call the chain with a multimeter).

FAQ: Frequent questions about the dismantling of Xiaomi Redmi Power Bank 20000 mAh