How to change the battery on Xiaomi Redmi 9: a complete guide with photos and nuances

Replacing the battery with Xiaomi Redmi 9 is one of the most popular procedures among the owners of this smartphone. After 2-3 years of active use, the battery capacity inevitably drops: the phone discharges in a few hours, turns off at 20-30% charge or refuses to hold charge at all. If you encounter these problems, do not rush to contact the service center - with the right approach, you can replace the battery yourself, saving up to 70% of the cost of repair.

In this article, we will go into detail about the entire process, from choosing a new battery to the final assembly of Redmi 9, you will learn what tools you will need, how to avoid disassembly errors, and what to do if the phone does not turn on after replacing, we will also analyze whether to buy the original battery or you can do with a quality analog, and give recommendations for extending the life of the new battery.

Preparation for replacement: tools and materials

Before you start disassembling the Xiaomi Redmi 9, make sure you have everything you need. Not even one tool can damage the body or internal components.

• 🔧 Set of screwdrivers (cross-haul) PH00, flat 1.5 mm, five-pointed Y00 back-coat)
• 🔨 Plastic mediators or shoulder blades (2-3 stains and stains are carefully stained)
• 🔥 Dryer or thermo-air station (to soften the glue under the back cover)
• 📦 New battery (original) BM4B or certified analogue with a capacity of 5020 mAh)
• 🧲 Magnetic mat or container (to avoid losing screws)
• 🧴 Isopropyl alcohol (90%+) (Cleaning contacts and removing glue residues)
• 📏 Suction cups (optional) (helps to lift the lid after heating)

Pay special attention to battery choice. Xiaomi's original batteries are labeled BM4B and have a factory-made hologram package. Patona, Baseus and Remax batteries are well-established, often with double-sided tape already glued, making installation easier. Avoid cheap no-name options: they may swell or fall short of the declared capacity.

⚠️ WARNING: If you've never taken your smartphones apart, practice on an old device or watch Redmi 9 video disassembly on YouTube.The body of this phone is glued very tightly, and careless movement can lead to cracks in the back panel.

Step 1: Turn off and disassemble Xiaomi Redmi 9

Start by turning off your phone completely. To do this, press the power button and select Turn it off. Wait until the screen goes out, and then start disassembling. Do not disassemble the phone when it is on, which can lead to short circuits.

Next, perform the following actions:

1. Take it down. SIM-card and memory card (if installed) The card tray is on the left end of the phone - use a paper clip or special key to extract.
2. Heat the back cover with a hair dryer for 2-3 minutes, holding it at a distance of 5-7 cm The temperature should be about 60-70 ° C - enough to soften the glue, but not melt the plastic. Especially carefully warm the edges near the buttons and charging connector.
3. Insert the plastic mediator into the gap between the lid and the body (start at the lower right corner, where the charging connector is located). Carefully drive the mediator along the edge, separating the lid. If you feel resistance, warm up the place again.

Once the lid is lifted, don't remove it completely, because it's still connected to the body by the fingerprint scanner plume. Carefully unplug the plume by pulling the mediator on the side, and you can take the lid away.

Step 2: Remove the old battery

Now you have to disconnect the old battery, and at this point, the key is not to damage the flexible plumes and board. First, unscrew the 11 screws that hold the metal plate above the battery. The screws are of different lengths, so remember or photograph their location:

• 🔩 4 screws under a five-point screwdriver (Y00) — plate-corner
• 🔩 7 screws under the cross screwdriver (PH00) — perimeter and centre

When you take off the plate, you'll see a battery connector -- a little white connector with an orange or red wire -- and you'll be able to gently tuck it in with a mediator and unplug it from the motherboard. If the connector is boiling, don't pull it by force, put some isopropyl alcohol on the contacts and wait. 10-15 seconds.

The battery itself is glued to the body with double-sided tape. To remove it, pull the black Pull-Tab that's under the battery. If the tape is missing or it's broken, use a plastic shovel to gently fit the battery on the side. Don't put metal objects under the battery -- it can break through and cause fire!

⚠️ Warning: If the battery is swelling, don't try to prick it or bend it. Place the phone in a sealed container and take it to a service center - bloated batteries are extremely dangerous!

Step 3: Installation of a new battery

Before installing a new battery, clear the seat of the old glue residue. Use isopropyl alcohol and a lilac-free wipe to do this. Make sure the contacts are free of dust or oxide film, which can lead to poor connection.

If you bought a battery with double-sided tape already glued (like most analogues), just remove the protective film and gently press the battery against the case. If there is no tape, you will need B-7000 glue or special double-sided battery tape (such as 3M 9448A).

After the battery is installed:

1. Connect the connector to the motherboard. It should snap with a click.
2. Install a metal plate in place and twist all 11 screws (watch out for their length!).
3. Connect the fingerprint scanner plume to the lid connector.
4. Press the back cover against the body, starting at the position near the charging connector, make sure it sits smoothly, without gaps.

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If the back cover is wobbly or not tight after assembly, warm it up with a hair dryer again (30-40°C) and press it with a heavy book for 10-15 minutes, which will help the glue to better grasp.

Step 4: First battery powering and calibration

After assembly, take your time to use the phone right away. First, calibrate the new battery so that the charge controller correctly determines its capacity:

1. Connect Redmi 9 to the original charger (or a quality analogue with Quick Charge 3.0 support).
2. Charge your phone to 100% and leave it on charge for another 1-2 hours.
3. Turn off charging and use the phone until it is completely discharged (until it turns off).
4. Repeat the charging-discharge cycle another 2-3 times, which will help stabilize the capacity.

If the phone does not turn on after replacing the battery, check:

• 🔌 Is the battery connector connected to the motherboard correctly.
• 🔋 Have you damaged the plumes during assembly (especially the fingerprint scanner).
• 🔧 Whether all screws are twisted (untwisted screws can cause short circuits).

If the problem persists, try to press the power button for 20-30 seconds – this sometimes helps to “wake up” the phone after a deep discharge.

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Calibration of the new battery is mandatory! Without it, the phone can show an incorrect percentage of charge or quickly discharge.

Frequent Mistakes and How to Avoid Them

Even experienced technicians sometimes make mistakes when replacing batteries, and here are the most common ones and ways to prevent them:

• 🔥 Hydrogen overheating → Keep the hair dryer at a distance. 5-7 Do not heat one point for longer. 10 Redmi plastic. 9 It can be deformed at a temperature higher 80°C.
• 🔩 Tangled screws → Rotors of different lengths! Use a magnetic mat and take pictures of their location before unscrewing.
• 📉 Damage to the fingerprint scanner plume → Remove it only after the lid is lifted. 1-2 Don't pull the plume!
• 🔋 Use of an uncertified battery → Cheap batteries can not only quickly fail, but also swell, damaging the motherboard.

Another common problem is that the phone doesn't see the new battery.

• Poor contact in the connector (check if the connector legs are bent).
• Power controller failure (try resetting via Recovery).
• Battery incompatibility (make sure it has a capacity of exactly 5020 mAh).

How much does it cost to replace the battery in the service vs independently?

The cost of replacing the battery with Xiaomi Redmi 9 in service centers varies depending on the region and type of battery.

As you can see from the table, self-replacement saves up to 50-70% of the cost, but if you are not sure about your skills, it is better to contact the service - especially if the phone is warranty (self-repair will cancel it).

When choosing a service, give preference to authorized Xiaomi centers or workshops with good reviews.

• 🚫 No guarantee for work (minimum 3 months).
• 🚫 Use batteries of unknown brands.
• 🚫 Refusing to show the original battery before replacement.

FAQ: Answers to popular questions