Replacement of the battery on Xiaomi Mi9 SE: detailed instructions with photos and tips

Xiaomi Mi9 SE is a compact flagship of 2019, which is still popular due to its powerful hardware and convenient size. However, after 3-4 years of operation, even the highest-quality battery loses up to 30-40% of capacity, and the phone begins to run out in a few hours. If your Mi9 SE turns off at 20-30% charge, quickly heats up or requires recharging 2-3 times a day, it’s time to think about replacing the battery.

In this article you will find step-by-step instructions for replacing the battery with a photo, recommendations for choosing an original or high-quality alternative battery, as well as tips for calibrating and extending the life of a new battery. We will look at what tools are needed, how to avoid common errors (such as damage to the display plume), and what to do if the phone does not turn on after replacing. Mi9 SE — its battery is glued to the body, and the power connector is located non-standard, which complicates the process for beginners.

Signs that it is time to change the battery

Fast discharge does not always mean battery wear — sometimes software failures or applications' background power consumption are the problem, but there are clear signs that indicate physical battery wear:

• 🔋 The phone turns off when 20-40% The indicator is normal, although the indicator shows a normal level.
• ⚡ The battery is discharged on 10-15% post 10-15 minutes without active use (e.g., in standby mode).
• 🔥 The body heats up in the battery area even with light load (video viewing, instant messengers).
• 📉 The time of operation from one charge was reduced in 2-3 compared to the new phone.
• 🔌 Charging is jerky: it quickly gains interest, then “hangs” at the same level.

If you know at least 2-3 items from the list, check the battery status through an engineering menu or applications like AccuBattery.

1. Enter the number ##4636##.
2. Go to the section Information about the battery.
3. If you look at the Health parameter, if it's below 80 percent, you need to change the battery.

⚠️ Attention: Mi9 SE firmware MIUI 12 engineering menu may not display battery health. In this case, use third-party utilities.

What battery to choose for Xiaomi Mi9 SE: original vs analogues

The original battery for the Mi9 SE is marked BM47 (or BM48 for some batches) and a capacity of 3070 mAh. However, after 2021, Xiaomi officially stopped supplying batteries for this model, so the market is dominated by analogues.

For the Mi9 SE, we recommend that you focus on quality analogues from proven brands: Green Cell GC-XM9SE, Baseus BAT-XM9SE or Remax RMB-307. These batteries are certified and have overheating protection. Avoid cheap no-name options - they often swell or lose capacity in 3-6 months.

When buying, pay attention to:

• 📦 Packaging: Xiaomi’s original batteries come in a white box with a hologram.
• 🔍 Marking: the model must be indicated on the battery (BM47/BM48), capacity and production date.
• 🔋 Contacts: high-quality batteries are golden in color, without traces of oxidation.

⚠️ Warning: Batteries with a capacity of more than 3200 mAh may incorrectly display the percentage of charge in the battery. MIUI. Calibration will require a full discharge-charging cycle (see section below).

Tools and preparation for battery replacement

To replace the battery with the Mi9 SE, you will need a special set of tools. Unlike models with a removable back cover (for example, the Redmi Note 4X), you will have to disassemble the phone almost completely, so it is important to prepare in advance.

Screen suction cup (∅ 5-7 cm)|Plastic blades (mediators) for disengaging the body|Screwdriver. T3 and T5 (magnetic)|Tweezers with curved ends|Hair dryer or thermo-air station (for softening glue)|New battery (see section above)|Isopropyl alcohol (90%+) clean-up|Double-sided tape or glue B7000 battery-lock-->

Also prepare the workplace:

• 🪑 Work at a table with good lighting (better to use a desk lamp).
• 🧲 Remove all metal objects – they can close contacts on the board.
• 📱 Put a second phone next to this instruction or print it out.
• ⚡ Turn off the power: take out SIM-cards and make sure the phone is turned off (clip the power supply) + Volume up for 10 seconds).

If you don't have experience disassembling smartphones, practice on an unnecessary device or watch video guides. the Mi9 SE has a brittle display plume - it's easy to damage if you take your screen off sloppy. Also be careful with the wireless charging coil (if installed) - it's glued to the back cover.

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Before disassembling, take a photo of each stage on your phone – this will help you put the device back together correctly, especially if you’re doing repairs for the first time.

Step-by-step instructions for replacing the battery

Now, to the most critical point, follow the instructions in strict order, and skipping the steps can damage your phone.

Step 1: Removing the back cover

The rear panel of the Mi9 SE is glued around the perimeter, so it needs to be heated to soften the glue. Use a dryer at minimum power (50-60 °C) or a thermal air station. Heat the edges of the body in a circle for 2-3 minutes.

Next:

1. Lock the suction cup at the bottom of the phone (near the USB-C connector).
2. Pull up carefully - there should be a gap.
3. Insert a plastic blade into the slot and slowly lead it along the body, separating the lid.

If the lid doesn't respond, heat it up again. Don't force it, you can break the latches or damage the antenna modules.

Step 2: Disconnect the battery plume

When you take the lid off, you'll see the battery glued to the case, and the first thing you do is disconnect it from the board, or you'll risk closing contacts.

1. Unscrew 5 screws (screwdriver T3), fixing the metal plate above the battery.
2. Carefully tuck the battery plume with a plastic spatula and disconnect it from the connector.

The power connector on the Mi9 SE is unconventional, hidden under a metal plate and has 4 pins (not 3, like most smartphones).

Step 3: Remove the old battery

The battery is glued to the body with double-sided tape to remove it.

1. Put a plastic shoulder blade on the battery from any angle.
2. Put a thin guitar string or plastic card under it.
3. Slowly drive the string under the battery, cutting the glue. Don't pull up, you can break the battery!

If the battery is swollen, don't prick it, it can cause fire. Instead, gently cut the glue around the perimeter and remove the battery entirely.

Step 4: Installation of a new battery

Before installing the new battery:

• Clean the seat from the residues of glue with isopropyl alcohol.
• Check the contacts on the board – they should be clean and not oxidized.
• Apply a new double-sided Scotch or B7000 glue to the back of the battery.

Set the battery so that the plume is not stretched, and connect it to the connector. Secure the metal plate with screws (T3).

Step 5: Assembly of the phone

Collect the phone in reverse order:

1. Lay down the display and camera plumes (make sure they are not twisted).
2. Stick the back cover. Warm it up with a hair dryer (40-50°C) to make sure it's safe and press it for 5-10 minutes.
3. Twirl the screws of the cover (screwdriver T5).

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After assembly, do not turn on the phone immediately - wait 10-15 minutes for the glue to grab and the battery "set" in place.

Calibration of the new battery and check of performance

After the battery is replaced, it needs to be calibrated so that the charge controller correctly displays the charge level. On the Mi9 SE, this is especially important because of the features of the MIUI firmware.

Do the following:

1. Full discharge: Use your phone before automatically turning off (do not charge even if a low charge warning appears).
2. Charge to 100%: plug in the original (18W) RAM and wait for full charge. Don't interrupt the process!
3. Reset battery data: go to Settings → Battery → Reset statistics (on some firmware, the path may differ).
4. Recycle: Recharge the phone before turning off and charge up to 100%.

If the phone still shows an incorrect charge after calibration (for example, it jumps from 50% to 20%), try the following methods:

• 🔄 Resetting settings (without deleting data): Settings → Additionally. → Resetting settings.
• 📱 Firmware update: sometimes charge display bugs are fixed in newer versions MIUI.
• 🔧 Manual calibration through ADB (for advanced users):

adb shell dumpsys battery set ac 1


adb shell dumpsys battery reset

⚠️ Warning: If the phone doesn't turn on after the battery is replaced, check: Is the battery plume connected to the connector (sometimes it falls out when assembly), is the contacts on the board closed (look for foreign metal particles). Is the display plume damaged (if the screen is not shining, but the phone vibrates when turned on) 90% of the time, the problem is solved by re-disassembling and checking connections.

Common Mistakes and How to Avoid Them

Even experienced craftsmen sometimes make mistakes when replacing the battery with the Mi9 SE. Here are the most common ones and ways to prevent them:

Another common problem is the rapid wear and tear of a new battery.

• 🔌 Use of non-original chargers (especially with higher power) 18W).
• 🌡️ Overheating of the phone (games, long-term use of the camera).
• 📵 Full discharge to 0% (lithium polymer batteries do not like deep discharge).

To extend the life of a new battery:

• 🔋 Try to keep the charge in the range of 20-80%.
• ❄️ Avoid overheating (do not leave your phone in the sun or near heat sources).
• 🔌 Use original or certified RAM (Quick Charge 3.0).

Cost of battery replacement in service vs self-repair

If you are not sure of your abilities, you can contact the service center, but the cost of replacing the battery with the Mi9 SE in 2026 varies widely:

Self-substitution is cheaper, but only if you already have the tools. If you buy them from scratch, the total cost is 2,000 to 2,500. ₽ (A set of screwdrivers, sucker, shoulder blades, hair dryer, in which case it is cheaper to contact a trusted service.

When choosing a service, pay attention to:

• 📋 Reviews - check Yandex.Maps or 2GIS.

FAQ: Frequent questions about replacing the battery with Xiaomi Mi9 SE