Xiaomi Mi9 is the flagship of 2019, which is still popular among users thanks to the powerful hardware and camera at the level of top models. However, after 4-5 years of operation, even the highest-quality battery loses up to 30-40% of capacity, and the smartphone begins to discharge in a few hours or turn off at 20-30% charge. If you encounter such problems, it is time to think about replacing the battery.
In this article, we'll look at three ways to replace your battery with a Mi9: in a service center, using tools yourself, and the artisanal method (which you should not use), which battery to choose, how much it costs, and how to avoid damaging the motherboard when disassembling, and why the battery can disappear after replacing the battery through USB-C and how to fix it.
The Xiaomi Mi9 has a glue battery, a brittle display plume and thin connectors that are easy to tear off. If you've never disassembled a smartphone, you better consult the professionals. But if you decide to try it yourself, follow our instructions Step-by-step.
Signs that the battery Xiaomi Mi9 is time to change
How do you know if the battery is the problem, not if there's a software failure or a damaged charger?
- 🔋 The smartphone is running out of power. 2-3 hours with moderate use (social networks, messengers, calls).
- ⚡ The charge "jumps": for example, with 40% drops 15%, or the phone is turned off when 20-30%.
- 🔌 Does not charge from the original charger or is charged only in a certain position of the cable.
- 🌡️ The battery is very hot even with minimal load (for example, during a call).
- 📉 In battery settings (Settings) → Battery. → Condition) the capacity shows less 70-75% starting-point (3300 mAhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh).
If you have at least 2-3 items on your list, you're probably wearing out the battery.
- Clean USB-C connector (sometimes the problem is oxidized contacts).
- The charger (try charging another smartphone).
- Power saving settings (Settings → Battery → Power saving mode – turn it off).
If you have a problem after this manipulation, it's time to change the battery, and then we'll figure out which one to choose.
What battery to buy for Xiaomi Mi9: original vs analogues
The original battery for the Mi9 is BM4D and has a capacity of 3300 mAh. However, after 2021, Xiaomi officially stopped supplying spare parts for this model, so it is almost impossible to find a “native” battery.
| Type of battery | Capacity | Price (2026) | Pluses | Cons |
|---|---|---|---|---|
| Original (b/u) | 3300 mAh | 1500–2500 ₽ | Guaranteed compatibility, no charging problems | Hard to find, wear and tear (if taken from another phone) |
| Analogue (quality) | 3300-3500 mAh | 800–1500 ₽ | New, often with increased capacity, easy to install | Risk of getting into a fake, possible calibration problems |
| Increased capacity | 4000-4500 mAh | 1200–2000 ₽ | Longer holds charge, suitable for active users | May not fit into the body, wear out faster, risk of overheating |
We recommend choosing high-quality analogues with a capacity of 3300-3500 mAh from proven brands:
- 🔹 Baseus – reliable batteries with overheating protection.
- 🔹 Remax – budget option, but with a guarantee of 6 months.
- 🔹 ZMI (Xiaomi subsidiary – almost original quality.
⚠️ Note: Don’t buy batteries with AliExpress for a lower price 500 ₽ — These are fakes with real capacity in 2-3 They can swell or damage the motherboard.
Before buying, check:
- The presence of protective film on the contacts (the originals and high-quality analogues have it).
- Production date (on the box or the battery itself) Lithium polymer batteries have a lifespan of 2-3 years, even when unused.
- Guarantee (good sellers give at least 3 months).
Preparing for replacement: security tools and measures
To replace the battery on Xiaomi Mi9, you will need:
Plastic blades (mediators) for disassembly|Set of screwdrivers (cross, five-pointed, Torx) T3)|Hair dryer or thermo-air station for softening glue|Screen suction cup|Thin-ended tweezers|New battery with adhesive base|Isopropyl alcohol (90%+) clean-up|Gloves and safety glasses (optional)-->
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.
⚠️ Attention: Xiaomi battery Mi9 It's soldered to the body with a special glue, and if you pull it off by force, you can damage the plume of the display or the motherboard. 60–80°C)! Before work begins: Turn off the phone and remove it SIM-Discharge the battery to the map. 20-30% — This will reduce the risk of fire if you damage it. → System system → Backup). 💡If you don’t have a hair dryer, you can use a regular household hair dryer, but keep it at a distance. 10-15 See from the phone to avoid overheating plastic parts. Mi9 Replace the battery and replace the battery. 5 Follow the instructions carefully, any error can cause your phone to break. 1: Removal of the back cover Rear panel Mi9 case-stick. To remove it: Heat the phone edge with a hairdryer (especially near the buttons and camera) during 2-3 Place the suction cup near the connector. USB-C And pull it up. Put a plastic blade in the gap, and you'll gently walk it around the perimeter, separate the lid. If the lid doesn't work, warm it up again. Don't force it, or you'll break the latches! Step. 2: Disabling the battery plume After removing the cover you will see: 🔋 Battery with black adhesive base. 📶 Antenna modules (do not touch them!). 🔌 The battery plume is a thin white connector near the bottom edge. To turn off the battery: Carefully put the plume in a plastic blade and unplug it from the motherboard. 5 minutes - this will discharge the residual current in the capacitors. ⚠️ Attention: If you accidentally touch the screwdriver contacts on the board, a short circuit may occur. Work with plastic or wooden tools only! Step 3: Remove the old battery pack The battery is glued to the case. To remove it: Tap the edge of the battery with a plastic blade. Pull the special black tape (pull-tab) that is under the glue. If there is no tape, carefully cut the glue with a knife, preheat it with a hair dryer. Don't use metal tools - they can puncture the battery! What to do if the battery is swelled? If the battery is swelled, don't try to pier it or bend it, this can lead to a new contact 4, to place it in the battery at the open window, and put it in front of the battery. Clean the installation site of the glue residue with isopropyl alcohol. Next: Stick the new battery (use double-sided tape or glue that came with it). Connect the plume to the motherboard. Make sure the battery is flat, free of skews. Step 5: Put the phone back together: Set the back cover and snap it around the perimeter. Warm up the edge hair dryer for better glue fixation. Turn on the phone and check the charge. 💡After replacing the battery, be sure to calibrate: completely discharge the phone, then charge to 100% Repeat the procedure without interruption. 2-3 Frequent errors and how to avoid them Even experienced masters sometimes make mistakes when replacing the battery. Here are the most common: Error Consequences How to avoid Using metal tools Puncture battery, short circuit Work only with plastic blades Strong heat puncture puncture (>100°C) Melting plastic parts, detachment of plumes Keep the hair dryer at a distance 10-15 temperature 60–80°C Incomplete shutdown of battery plume Short circuit when working with board Wait 5 minutes after disconnection Installation of the battery of increased capacity Fragmented fit of the cover, overheating Select the battery with the original capacity (3300 mAh) Another common problem is that the phone doesn't charge after the battery is replaced: 🔌 Poorly connected battery plume (check fixing connector). 🔋 Low-quality battery (try another one). 📱 Power controller settings are lost (reset via Fastboot is needed). If the phone turns on after replacing but does not charge, try: Disable and reconnect the battery plume. Wipe the contacts USB-C Enter Fastboot mode (clamb Volume down) + Power) and execute command: fastboot oem edl Then flash the phone through the Mi Flash Tool (instructions are on the phone. 4PDA). How much does it cost to replace Xiaomi battery? Mi9 2026 Replacement costs depend on where and how you do it: Replacement method Price (2026) Pros of Cons Self 800–2000 ₽ (Savings, repair experience Risk of damage to the phone Service center 2500-4000 ₽ (Guarantee, professional repair Expensive, possible queues Mobile master (exit) 3000-5000 ₽ Comfortable, fast High price, risk of running into a dilettante In service centers Xiaomi officially do not change batteries on the market. Mi9, Since the model is discontinued. But many private workshops are taking this job: 🏙️ Moscow: 3000–4,000 ₽. 🏙️ St. Petersburg: 2800–3500 ₽. 🏙️ Regions: 2000–3000 ₽. If you decide to give the phone for repair, check: Availability of a work warranty (at least 3 months), reviews about the workshop (on Yandex.Maps or 2GIS), whether they use original or certified analogues of batteries. Alternative ways to extend the life of the battery If replacing the battery is not yet included in your plans, you can try to extend the life of the old battery: 🔄 Calibration: Completely discharge the phone, then charge to 100% without interruptions. Repeat 3 times. ⚡ Charging optimization: Use original RAM, avoid wireless charging (it heats the battery). ❄️ Temperature control: Do not leave your phone in the sun or near heat sources. 📵 Energy saving: Turn off the background activity of applications (Settings) → Battery. → Optimization. You can also try resetting your phone to factory settings: Go to Settings. → The phone. → Setting reset. Select Erase all data. After reset, don't restore the data from the backup -- set the phone as new. This will help if the problem was a software failure of the power controller. 💡If the phone is turned off when 20-30% It's a charge, but after the reset, it shows a normal level -- a problem with the battery sensor. Try calibrating it with the engineering menu ##4636##, section “Battery information"). FAQ: Frequent questions about Xiaomi battery replacement Mi9 Can I replace the battery with Xiaomi? Mi9 No, that's not possible. Mi9 built-in, and to replace it requires a complete disassembly of the body. Any “contactless” methods (e.g. charging-discharge) only give a temporary effect and do not solve the problem of battery wear. How long does it take to replace the battery in the service? On average, the procedure takes 1-2 hours if there is no queue in the workshop. In on-site repairs, the wizard can cope in 30-40 minutes. Self-replacement without experience can take 3-4 hours. Why does the Xiaomi Mi9 battery fail to turn on? There may be several reasons: The battery plume is poorly connected (check the fixation of the connector). Short circuit during the disassembly of the phone (if the battery is not rated, for example, if the battery is not rated by the 4000). Technically, yes, but it's fraught with problems: the battery may not fit into or deform the case; the heating will increase when charging; the power controller may misrepresent the level of charge; the battery's life is usually shorter than the original battery. We recommend installing batteries with a capacity of no more than 3,500 mAh. How to dispose of an old battery from Xiaomi Mi9? Lithium polymer batteries can't be thrown away in the trash, they need to be taken to special reception points: 📍 Electronics stores (Svyaznoy, M. Video, Eldorado - they have battery bins). 📍 Xiaomi Service Centers. 📍 Recycle points (see "battery recycling" in your city) seal the battery contacts with tape before disposal to avoid short circuits.