Why the Redmi 8 battery fails and when to change it
Xiaomi Redmi 8, released in 2019, is equipped with a non-removable battery capacity of 5000 mAh. Despite the promised manufacturer 2-3 years of uninterrupted operation, the real battery life rarely exceeds 18-24 months with active use.
✅ The phone discharges in 4-5 hours at a standard load (social networks, instant messengers, calls), although previously held the charge for a day.
✅ The device spontaneously turns off at a charge level of 20-30% and does not turn on without recharging.
✅ The battery is swollen - the phone body has become convex, the screen or back cover move away from the frame.
✅ Redmi 8 overheats while charging or running, even if resource-intensive applications are not running.
If you see any of these symptoms, you don't have to wait to replace them, because a swelling battery can damage the motherboard or the screen, which can lead to costly repairs, and lithium polymer batteries can become fire-prone when they deform.
Which battery to choose for Xiaomi Redmi 8: original vs analogues
The first thing to start with is choosing a quality battery. Xiaomi’s original Redmi 8 batteries are coded MB-J12B (or BM4H in some batches).
- 🔋 Compliance with factory parameters: capacity of 5000 mAh, voltage of 3.85 V.
- 🛡️ Compatibility guarantee with the phone’s power controller (no risk of overheating or rapid wear and tear).
- 📦 In the kit is a heat pad and bilateral tape for fixation.
However, the original batteries cost from 1500 to 2500 rubles, and their counterfeits are found even at official sellers.
| Brand | Model battery model | Capacity | Price (2026) | Features |
|---|---|---|---|---|
| ZMI | ZB01 | 5,000 mAh | 1200–1500 ₽ | High quality assembly, minimum self-discharge |
| Baseus | BS-BAT08 | 5,200 mAh | 1300–1600 ₽ | Increased capacity, but may slightly protrude |
| Patona | PAT-RM8 | 5,000 mAh | 900–1200 ₽ | Budget option, but less resource of charging cycles |
⚠️ Warning: Buy batteries only from trusted sellers (e.g. AliExpress 98 rating%+, Avoid offers cheaper than 800 rubles - this is a guaranteed fake with a capacity 2-3 times lower than the declared one.
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Before buying, check the battery with a multimeter (if possible).The voltage of the new battery should be in the range of 3.7-3.9 V.
Battery Replacement Tools: What You Need
To replace the battery on the Redmi 8 will require a minimum set of tools, without them the risk of damage to the plumes or the body of the phone increases significantly:
- 🔧 Plastic blades (mediators) - for careful liding and disconnection of plumes.
- ⚙️ The screwdriver (PH00 or PH0) — screw-twisting.
- 🔥 Dryer or thermo-air station - for softening the glue (temperature 60-80)°C).
- 🧲 Magnetic mat or container – to avoid losing small screws.
- 🩹 Alcohol wipes - to clean contacts and remove glue residues.
- 🔋 New bilateral scotch (e.g, 3M 9448A) — battery-lock.
⚠️ Warning: Do not use metal blades or knives - they can puncture the battery or damage the plumes! Also avoid overheating the body with a hairdryer: keep it at a distance of 10-15 cm and do not direct the air flow to the screen or camera.
Turn off the phone and remove it. SIM-memory-card|
Charge your phone to 30-50% to avoid short circuits)|
Prepare a workspace with good lighting |
Take photos of the interior structure before disassembly (in handy for reverse assembly)|
Wear an antistatic bracelet or touch a grounded object periodically-->
Step-by-step: how to disassemble Xiaomi Redmi 8 and replace the battery
The process of replacing the battery with the Redmi 8 takes 30-60 minutes, if you have experience. If you are doing this for the first time, be patient.
Step 1: Removing the back cover
1. Turn off the phone and place it down on a soft surface (such as a napkin).
2. heat the hair dryer edge of the back cover around the perimeter for 2-3 minutes - this will soften the glue.
3. Insert the plastic blade into the gap between the lid and the body (start at the bottom edge where the charging connector is).
4 Carefully drive the blade along the edge, gradually detaching the lid. If the glue does not respond, repeat the heating.
Step 2: Shutting off the battery
1. Once you remove the lid, you'll see the battery covered with black film. Don't pull it -- it's a heat pad!
2 Unscrew 5 screws that fix the metal plate above the plumes (they are of different sizes - remember the location!).
3. With a plastic spatula, gently tuck the battery connector (it is white, located in the upper part) and disconnect it from the motherboard.
⚠️ Warning: If the battery is swelling, do not pierce it or press it from above. If the lithium polymer battery is damaged, it can ignite or emit toxic gases.
Step 3: Remove the old battery
1. Put a plastic blade on the battery from any angle, and it's glued to the body, so it takes a lot of effort.
2 If the battery is not amenable, heat it with a hair dryer (not higher than 60 ° C) and pull on special "ears" (white ribbons on the sides).
3. Remove the remnants of old glue with an alcohol napkin.
Step 4: Installation of a new battery
1. Remove the protective film from the new battery and glue it to the old one using double-sided tape.
2. Connect the battery connector to the motherboard (it should click with a slight click).
3.Make sure that the plume is not bent and does not touch other components.
Step 5: Reverse Assembly
1. Place the metal plate in place and twist the screws (do not pull!).
2. Stick the back cover. You can use B-7000 glue or a special glue for smartphones for reliability.
3. Place the phone under a press (such as a stack of books) for 10-15 minutes to get the glue.
What if the phone doesn’t turn on after replacement?
Calibration of the new battery: why it matters
After the battery is replaced, it needs to be calibrated so that the phone’s power controller correctly determines the charge level, and skipping this step can lead to inaccurate battery performance (for example, the phone will turn off at 20% charge).
Calibration instructions:
- Charge your phone to 100% and leave it on charge for another 1-2 hours.
- Turn off charging and use the phone as normal until it’s down to 0% and off.
- Wait 5-6 hours, then charge it again to 100% without interruption.
- Repeat the discharge-charging cycle 2-3 times.
⚠️ Note: Do not use Quick Charge during the first time. 3–5 Charge your phone with a standard cable from the network. 5V/2And.
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Calibration helps the power controller to learn new battery characteristics, without which the phone can either show the wrong percentage of charge or run out quickly.
Frequent Battery Replacement Mistakes and How to Avoid Them
Even with a careful battery replacement, beginners often make mistakes that cause their phone to break, and here are the most common ones and ways to prevent them:
- 🔌 Damage to the battery plume occurs when the connector is sloppy, always squirt it from the side, not pull it up.
- 🔥 Overheating the body with a hair dryer - can melt plastic elements or damage the screen.Keep the hair dryer at a distance and use the minimum temperature.
- 🧲 Loss of screws is a different length of screws in Redmi 8, and if you mix them up, you risk damaging the motherboard.
- 🔋 Use of poor-quality glue -- cheap glue can fall off in a week. 3M 9448A or B-7000.
- ⚡ Ignoring calibration – without it, the phone will not display the charge level correctly, which will lead to sudden blackouts.
If after replacing the battery, the phone began to overheat, quickly discharge or not charge, the likely reasons are:
- Battery defect (check the voltage with a multimeter).
- The plume or power controller is damaged.
- The battery connector is not properly connected.
Should I change the battery myself or contact the service?
Self-replacement of the battery on Xiaomi Redmi 8 will cost 1000-2500 rubles (battery price + tools). In the service center for the same work will ask 2000-4000 rubles, but you will get a warranty for installation (usually 3-6 months).
When to contact the service:
- 🛠️ If the battery is swollen and deformed the body - the risk of damage to the board is too high.
- 🔧 If you don’t have experience disassembling electronics, one mistake can cost more than saving money.
- ⚡ If the phone does not turn on or behaves unstable after replacement.
When you can change yourself:
- 💰 If you want to save money and are confident in your skills.
- 🔋 If the battery just sat down and didn't swell.
- 🛠️ If you have the right tools and time.
💡 Tip: If you decide to change the battery yourself, film the process. This will help avoid errors in the reverse assembly and will be proof to the service if something goes wrong.