Xiaomi Mi8, released in 2018, is still popular with users due to its powerful hardware and up-to-date firmware. However, after 4-5 years of operation, even the best battery loses up to 30-40% of capacity, and the smartphone begins to run out in a few hours or turn off at 20-30% charge. If you notice these symptoms, it’s time to think about replacing the battery.
In this article, we will discuss three ways to replace: in a service center, using tools yourself, and an “artisanal” method for emergency situations, you will learn how to choose a quality battery, avoid disassembly errors, and calibrate a new battery correctly so that it lasts longer. We will pay special attention to the nuances of Mi8: the location of the plumes, the type of glue under the battery and compatibility with analogues from other Xiaomi models.
Signs of battery wear: when is it time to change?
Lithium polymer batteries in smartphones are degraded even when used with care. Here are key signs that the Xiaomi Mi8 battery needs replacement:
- ⚡ The smartphone discharges by more than 50% per 2-3 hour in standby mode (no active use).
- 🔋 When charging is connected, the charge level “jumps” (for example, from 10% immediately to 40%).
- 🔌 Charging is interrupted with the message "Not the original cable," although you are using a proprietary adapter.
- 🌡️ The smartphone body heats up strongly in the battery area (even with minimal load).
- 📉 In the Settings menu → The battery state shows less than 80% of the original (3400 mAh).
If two of the items on the list match, the battery is worn out. It is dangerous to delay replacement: a degraded battery can swell and damage the display or motherboard, in extreme cases, it leads to a short circuit and a complete failure of the smartphone.
⚠️ Warning: If the Mi8 case becomes convex or there are gaps between the screen and the frame, turn off the smartphone immediately and don't try to charge it!
Battery selection: original vs analogues
The original battery for Xiaomi Mi8 has an MBJ4057 and a capacity of 3400 mAh. However, after 2020, Xiaomi officially stopped supplying batteries for this model, so the market is dominated by analogues.
| Type of battery | Advantages | Deficiencies | Price (2026) |
|---|---|---|---|
| Original (b/u)Article: MBJ4057 | Guaranteed compatibility, stable operation | Hard to find, wear and tear (if taken from another smartphone) | 1 500–2 500 ₽ |
| Brands: Patona, Baseus, Remax | Capacity 3500-3600 mAh, protection against overheating | Prices above average, fakes are possible | 1 200–1 800 ₽ |
| The budget analogue of the Brand: Green Cell, Xiaomi Original (non-OEM) | Low price, ease of purchase | Capacity is often understated (2800-3200 mAh), rapid wear and tear | 600–1 000 ₽ |
| Increased capacity (3,800–4,000 mAh) | Longer holds charge, suitable for active users | The thickness of the original, may not fit into the body or deform it | 1 800–2 500 ₽ |
When buying, pay attention to:
- 🔍 Availability of protection against overcharging/overheating (to be indicated on the package).
- 📏 Battery thickness: original 3.85 mm. Analogues thicker than 4 mm may not fit.
- 🔋 Connector type: The Mi8 is JST 1.0 (not to be confused with JST 1.25 on other Xiaomi models!).
- 🛡️ Guarantee: Reliable sellers give a minimum of 6 months.
Where to buy? Best options:
- 🛒 Official stores: Xiaomi Store (if you find the original), AliExpress (sellers with a rating of 98%+).
- 🔧 Specialized sites: BatteryShop.ru, Akku-Russia.ru.
- 🏬 Local service centers (sometimes sell quality analogues in bulk).
⚠️ Warning: Avoid batteries labeled "For Mi8/Mi9" - they are versatile and often don't fit in size. Also, don't pick up batteries without the Li-Polymer label (this can be dangerous Li-Ion fakes).
💡
Check the reviews on the 4PDA or Mi Community forums before buying, often posting photos of real batteries with the capacity after the tests.
Preparing for replacement: tools and safety
For a battery replacement in Xiaomi Mi8, you will need:
Disconnect the smartphone and remove SIM-map|Charge the battery to 30-50% (do not charge the bloated!)|Prepare a workplace with good lighting|Wear an antistatic bracelet (or work on a wooden surface)|Have on hand medical alcohol to clean contacts-->
- 🔧 Tools: Plastic blades (mediator) - 2-3 pieces. Cross screwdriver PH00 (for screws of the case); Suction cup for the screen (diameter 5-7 cm); Tweezers with curved ends; hair dryer or thermo-air station (for softening of glue).
- 🧴 Consumers: Double-sided tape or glue B-7000 (to lock the new battery); Isopropyl alcohol (90%+) for cleaning contacts; napkins without pile.
- 🛡️ Safety measures: Work with gloves — lithium polymer batteries are toxic when damaged. Don't use metal tools to slam the battery (risk of short circuit!) If the battery is swelling, don't pierce it or bend it.
An important nuance: in the Xiaomi Mi8, the battery is glued to the body with double-sided high-strength tape. To remove it, you will need to heat the body to 60-70 ° C (not higher!).
- Turn the dryer on at minimum power.
- Heat the back cover in circular motions for 2-3 minutes.
- Try to tamper with the battery with a plastic blade from the edge (where the plume is located).
Don't use sharp objects, you can damage the display plume or the motherboard, and if the glue doesn't respond, repeat the heat.
What to do if the battery is too tight?
Step-by-step instructions for replacing the battery
Now, to the process itself, follow the instructions in strict order to avoid errors.
Step 1: Removing the back cover
1. Turn off your smartphone and remove the tray for SIM-map.
2. heat the hair dryer edge of the back cover (especially near the power and volume buttons).
3. With a suction cup, lift the lid at the bottom edge (where the USB-C connector is).
4 Carefully apply a plastic blade around the perimeter, starting at the corners. Don't force it, the lid is held on the latches.
Step 2: Shutting off the battery
1 Unscrew 10 screws (they are of different lengths - remember the location!).
2. disconnect the battery plume with tweezers (it is under a black protective tape).
3. Check the voltage on the contacts of the battery multimeter (should be 0 V). If there is a voltage, repeat the shutdown.
Step 3: Remove the old battery
1. heat the battery with a hairdryer (as described above).
2. Put the battery on the edge where there are no components of the board. Use a plastic blade or thread.
3. If the battery is swelling, do not press on it - carefully remove, tilting the body.
Step 4: Installation of a new battery
1. Clean the seat with alcohol from glue residues.
2. Remove the protective film from the contacts of the new battery and glue it to a double-sided tape.
3. Connect the battery plume to the motherboard and fix it with tape.
Step 5: Build a Smartphone
1. Make sure all plumes (display, cameras, speaker) are connected.
2.Turn the screws (starting with the longest ones).
3. Press the back cover until the snaps of the latches.
Important: Don't turn on your smartphone right away. Let the glue hold for 10 to 15 minutes.
1. Correct connection of the battery plume.
2. the presence of voltage on the contacts (should be ~3.8 V).
3. Integrity of flexible plumes (especially display).-->
Calibration of the new battery
The new battery requires calibration so that the charge controller can correctly determine its capacity, and by skipping this step, you run the risk of getting inaccurate data on the level of charge.
Calibration instructions:
- Full discharge: Use your smartphone before automatically turning off (don’t manually turn off!).
- Charging without interruption: Connect the original charger and charge up to 100% (at least 3 hours).
- Battery Reset: Go to the Engineering menu: ##4636##Select Battery Information →Reset statistics.
- Recycle: Discharge the smartphone to 0% and recharge to 100%.
After calibration, check the actual battery capacity using the following applications:
- AccuBattery (shows wear and discharge rate).
- CPU-Z (Battery tab → Health parameter)
- Mi Battery Doctor (official app from Xiaomi)
⚠️ Warning: If after calibration, the smartphone is less than 3,000 mAh, there may be a problem with the power controller on the motherboard.
Frequent Mistakes and How to Avoid Them
Even experienced users sometimes make mistakes when replacing the battery. TOP-5 Problems and ways to prevent them:
| Mistake. | Effects of consequences | How to avoid |
|---|---|---|
| Use of metal tools | Short circuit, board damage | Work only with plastic blades |
| Battery overheating with a hairdryer (>80°C) | Bloating or ignition | Hold the hair dryer at a distance of 10 cm, use minimum power |
| Incorrect connection of the plume | The smartphone is not powered on or charged | Check the polarity of contacts (red – “+”, black – “-”) |
| Use of low-quality glue | Battery goes off when it falls | Use B-7000 glue or original Xiaomi Scotch |
| Sizing omission | Rapid wear of the battery, incorrect charge indicator | Perform 2-3 full charge/discharge cycles |
Additional advice:
- 🔌 If the smartphone does not charge after replacing, check the integrity of the USB- port (contact may have gone away).
- 📱 If the screen doesn't respond to touch, most likely the display plume has gone away - disassemble the smartphone and connect it again.
- 🔋 If the new battery is rapidly discharged, check the background processes in Settings → Battery.
Alternative methods of substitution
If you are unsure of your abilities or don’t have time to repair yourself, consider alternatives:
- 🏢 Official Xiaomi Service Center: Pros: 6-12 months warranty, original parts. Cons: high price (2,500-4000 ₽), long wait (1-2 weeks).
- 🔧 Local workshops: Pros: 1,000–2,000 ₽, quick repairs (1–2 hours) Cons: the risk of installing a substandard battery.
- 📦 Postal repair: Pros: no need to go to the service, price from 1,500 ₽ Cons: the risk of losing your smartphone during shipping.
Advice: Before contacting the service, specify:
- What battery will be installed (ask for a photo of the package).
- Do you have a job guarantee and spare parts?
- How long will it take to repair it?