Xiaomi Mi8 was the flagship of its time, offering users advanced specs and high-quality AMOLED screen. However, time does not spare lithium-polymer batteries, and after a few years of active operation, the battery capacity drops significantly. The device begins to run out in the cold, turn off at 20-30% charge or work only half a day instead of a full day.
The process of restoring your smartphone to health requires care, because the interior layout of the model is quite dense. NFC-antenna and plumes, which are easily damaged if you carelessly handle. However, with a minimum set of tools and technology, you can carry out the replacement yourself, saving a significant amount of money on the services of the service center.
In this article, we will take a look at every step of the way, from the work place preparation to the post-assembly seal check, how to properly unstick the back panel, what risks are there when working with Li-Pol batteries, and what to look for when buying a new part, the main thing is to take your time and follow the instructions strictly so as not to turn a simple repair into a difficult problem with the restoration of plumes.
Tools and workplace preparation
Before you start dismantling the Xiaomi Mi8, you need to organize a comfortable and safe workspace. You will need a well-lit desk, preferably with a white or light surface, so that small screws and details are clearly visible. The absence of drafts and dust will also play an important role, since the inside of the case should not get debris, which can cause short circuits or sticking buttons.
To perform a quality battery replacement, a specific set of tools will be required, which is often sold by a smartphone repair kit. The base list includes a dryer (construction or household with a narrow nozzle), plastic mediators (scapula), a suction cup, a set of cross sting screwdrivers and tweezers. It is also strongly recommended to prepare isopropyl alcohol or a special solvent B-7000 for softening the glue.
- 🛠️ Heating element: A hair dryer or heat mat to heat the adhesive layer under the back cover.
- 🔧 Set of screwdrivers: Necessarily the presence of a thin cross screwdriver (PH00 or PH000) hull-rotor.
- 📱 Plastic blades: For gently snapping clips and separating plumes without damaging electronics.
- 🧲 Magnetic mat or organizer: To avoid losing tiny screws of different sizes during the disassembly process.
Pay special attention to safety when working with heating devices. The heating temperature should not exceed 80-90 degrees Celsius, so as not to damage the display matrix or plastic elements of the case. If you use a household hair dryer, keep it at a distance of 3-5 cm from the surface of the phone and constantly move the flow of hot air, warming the perimeter evenly.
☑️ Preparation for repairs
Diagnostics and selection of a new battery
Before you start physical work, it is important to make sure that the problem lies in the wear of the battery chemistry, and not in the software failure or malfunction of the power controller. On the Xiaomi Mi8, you can conduct initial diagnostics through an engineering menu or special applications, but the most accurate result will give a visual inspection of the old battery after removal. Bloating, oxidation of contacts or a sharp smell of the electrolyte are clear signs that the element requires urgent disposal.
When choosing a new battery for Xiaomi Mi8 should focus on the original models or quality analogues from proven brands. The capacity of the standard battery is 3400 mAh, and attempts to find versions with increased capacity often lead to the purchase of poor-quality goods with a regated label. Original batteries are marked BM3E and protective holograms, as well as a built-in protection board (BMS) of high quality.
The spare parts market is full of fakes, so when buying, pay attention to the date of production. Lithium polymer cells degrade even when stored, so a battery that has been in storage for three years will have a life significantly lower than stated. It is better to buy a slightly more expensive, but fresh copy than to save and in six months to look for a replacement.
How to check the date of production of the battery?
| Characteristics | Original / High quality | Cheap copy |
|---|---|---|
| Capacity | Real 3400mAh | Claimed 3400+, real 2000-2500 mAh |
| Weight. | Complies with the standard (~60-65 g) | It is often easier due to material savings. |
| Controller (BMS) | High-quality ration, protection from overheating | Simple fees, possible failures in work |
| Cycle resource | 500-800 full cycles | 100-200 cycles before losing 20% capacity |
Removal process of the back cover
The most difficult and risky step of replacing the battery on Xiaomi Mi8 It's a neat removal of the back glass panel, and it's glued all around the perimeter, and any sudden movement can cause cracks. Start by turning off your smartphone and removing the tray. SIM-Then turn on the hair dryer and evenly warm the edges of the back cover during the course of the 2-3 minutes, periodically checking the temperature with your finger - the glass should become hot, but not burning.
After warming up, glue the suction cup at the bottom of the back, closer to the Mi logo, but not at the very edge. Pull the suction cup up, creating a small gap between the glass and the frame, and immediately insert a thin plastic blade or mediator into the resulting slit. Do not use metal objects, as they can break the glass or damage the internal components.
⚠️ Attention: Don't try to pull the lid apart! The glue should soften. If the shoulder blade is struggling, warm up the problem area again with a hairdryer.
Drive the blade along the perimeter of the body, gradually cutting through the adhesive layer. Be especially careful in the area of the main camera module and the fingerprint scanner, because there are plumes going to the motherboard. If you feel resistance, then the glue in this place is not warmed up, and you need to add heat. Move slowly, peeling the lid 1-2 millimeters at a time.
Once the adhesive layer around the perimeter has been overcome, gently lift the back cover. Don't put it away far, as it may be glued to the fingerprint scanner plume (in some revisions) or NFC-An antenna that can be mounted on glass. Mi8 antenna module is often located on the inside of the cover, so it should be disconnected extremely carefully, putting the connector on the nail or plastic blade.
Disassembly of the internal layout
Once the back cover is successfully removed, you will see the inside of the smartphone, and the first thing you need to do is to disconnect the battery plume from the motherboard, which is a critical safety step: any manipulation inside the phone should only be done after the device has been turned off, and find the battery connector, which is usually located at the bottom or center of the board, and gently disconnect it by putting it up from the bottom.
Next, you have to remove the plastic cover covering the motherboard and the top of the battery, which is secured by several screws of different sizes. Unscrew them, fold them in the organizer and remove the cover. Under it you will see the main board, the camera module and the top plume. To access the battery in the Xiaomi Mi8, you often need to remove the motherboard or at least lift it, because the battery is closed with a metal plate or the motherboard itself.
Carefully disconnect all the necessary plumes: display, cameras, antenna cables. Unscrew the screws that hold the motherboard and remove it from the case. Now the path to the battery is free. The battery is glued to the frame of the case on double-sided tape. Use a plastic card or a special hood with a suction cup to extract it.
- 🔋 Turn off the plumes: Always turn off the battery first and plug in the last one.
- 🧹 Cleaning: Before installing a new element, remove the remnants of the old glue from the frame of the case.
- 🧤 Static: Try not to touch the contacts of connectors and chips on the board with your fingers.
If the battery is sitting very tight and doesn't want to separate, you can slightly warm the back of the case (where it's now empty) with a hairdryer to soften the glue under the battery. Also effective isopropyl alcohol: pour some liquid under the edges of the battery and wait a couple of minutes. Never use sharp metal objects to tamper with the battery - a puncture of the lithium polymer cell causes instant ignition!
Installation of a new battery and assembly
When the old battery is removed, thoroughly clean the seat of glue and dirt residues.The new Xiaomi Mi8 battery usually comes with an already applied adhesive layer or complete with adhesive strips. Remove the protective film and gently install the power supply element into its place, combining the connector with the response part on the plume or board (if the plume is left on the battery).
Before the final assembly, you need to do an initial check. Connect the new battery plume to the motherboard and press the power button. If the screen catches fire and the phone starts charging or shows a charge level, then the installation was successful. If there is no reaction, double check the connector density and make sure that the battery is not discharged to zero (sometimes you need to hold them on charging for 10-15 minutes).
The assembly process is done in reverse order. Set the motherboard, lock it with screws. Connect all the plumes: displays, cameras, antenna cables. Make sure each connector snaps to a characteristic clicks. Put the antenna module (NFC) in place if it was separate, or glue it to the inside of the back cover if it was on it.
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Before sticking the back cover, be sure to check the touchscreen, cameras, speakers and vibrator in the disassembled state, which will save time if you need to reconnect something.
Apply the new glue (B-7000 or special adhesive for smartphones) with a thin strip along the perimeter of the frame of the body and on the back cover. Let the glue dry for 1-2 minutes to a state of stickiness, then carefully align the cover with the body and tightly press the edges. For better adhesion, you can use special clips or tightly rewind the phone with rubber harnesses for 30-60 minutes.
Calibration and primary start
After you build your smartphone, don't rush to use it actively. The new battery needs an initial calibration to correctly display the charge level by the power controller. Put the phone on charge when it's off and wait until the indicator shows 100%. Then turn on the device without disconnecting from the network, and leave for another hour.
Then you can use the phone in normal mode until it is completely discharged and automatically turned off. This charge-discharge cycle helps the system correctly determine the real capacity of the new element. In the early days of use, the Xiaomi Mi8 can heat up slightly in the area of the camera - this is a normal process of grinding the chemical processes inside the new cell.
⚠️ Warning: If the phone is too hot or discharges quickly in the first days, you may have a defective battery or a poorly connected train.
To monitor the status of the new battery, you can use built-in MIUI tools or third-party applications like AccuBattery, which will help you track the wear rate and real capacity over time. With proper operation and quality spare parts, your Xiaomi Mi8 will again enjoy the autonomy comparable to the new device.
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Qualitative calibration in the first charging cycles extends the life of the new battery and ensures the accuracy of the display of the percentage of charge.