Xiaomi Redmi Note 8 is one of the most popular smartphones of 2019, but even after 3-4 years of active use, the battery begins to “die”: quickly discharges, swells or turns off at 20-30% charge. Replacing the battery in the service center will cost 2-4 thousand rubles, but if you want you can save and do everything yourself. In this guide, step-by-step instructions with a photo, a list of necessary tools, tips for choosing a new battery and critical nuances that miss 90% of guides on the Internet.
The replacement process doesn’t require a soldering iron or special skills, but it does require care: the Redmi Note 8’s body has fragile plumes and the battery is glued to the back cover. We’ll break down two methods of disassembling an old battery (heated and unheated), explaining how to avoid damaging the display, and provide a table of compatible batteries with AliExpress. If you’ve never taken your smartphone apart, don’t worry: with the right approach, the risk of breaking something is minimal.
Signs that it is time to change the battery
Sometimes the problem is background processes, a faulty charger or a damaged USB-C connector. Before you start replacing, check for these symptoms:
- 🔋 The smartphone is running out of power. 2-3 hours with moderate use (social networks, messengers).
- ⚡ Charging jumps: for example, from 50% immediately falls to 15% or “stuck” at one value.
- 📱 The body swelled (notably by the gap between the screen and the back cover or the "slamming" display when pressed).
- 🔥 The phone warms heavily during charging or playing (the battery can heat up to a point). 50-60°C).
- 🛑 Turns off when 20-30% Charge, although in the settings shows normal wear.
If at least 2-3 points match, the battery definitely needs to be replaced. For accurate diagnosis, look at Settings → Battery → Battery → Battery Status. If it indicates wear and tear of more than 25% or capacity below 3500 mAh (at the initial 4000 mAh), it is time to act.
⚠️ Attention: Bloated battery is dangerous! It can burst or ignite when mechanically exposed. If the case is deformed, don't try to disassemble your smartphone at home, contact the service.
What battery to choose for Redmi Note 8
The original battery for the Redmi Note 8 is BM47-marked and has a capacity of 4000 mAh. However, the market is full of fakes and "improved" versions. We tested 5 popular options - the results in the table below.
| Model/brand | Capacity | Price (rupe) | Pluses | Cons |
|---|---|---|---|---|
| Original Xiaomi BM47 | 4000 mAh | 2500-3500 | 100% compatibility, long service life | Expensive, hard to find. |
| Baseus | 4200 mAh | 1200-1800 | Big capacity, good reviews. | Maybe not fit into the hull. |
| Patona | 4000 mAh | 900-1500 | Low price, easy installation | Losing capacity fast |
| ZMI (a sub-brand of Xiaomi) | 4100 mAh | 1800-2200 | Quality contacts, stable work | Rarely available. |
For replacement, we recommend the original battery or Baseus/ZMI. Avoid the "no-name" versions with AliExpress for 500-700 rubles - they often have an understated real capacity (for example, instead of 4000 mAh give 2500-3000) and can damage the power controller.
When buying, check:
- 📦 Presence of protective film on contacts (original films always have it).
- 🔍 Marking BM47 or Redmi Note 8 on the body.
- 📏 Dimensions: length 73 mm, width 68 mm, thickness 3-4 mm.
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Before you buy, ask the seller to send a photo of the battery with a multimeter showing the voltage.
Battery replacement tools
You don't need professional tools, but you can't do without a minimum set.
- 🔧 Plastic blades (2-3 (p.c.) to separate the shell.
- 🔨 Thin screwdriver (cross, size) PH00 or T3).
- 🔥 Hair dryer or thermo-air station (for softening glue).
- 🧴 Isopropyl alcohol (90%+) glue-cleaner.
- 🧲 Magnetic mat or screw box (so as not to lose).
- 📱 New battery (see section above).
- 🔌 Tweezers for working with plumes.
If you don't have a hair dryer, you can do with a needle and thread (the method of "cutting" glue), but it's longer and more risky, and you can also use tape to fix the plumes and the magnifier, so you don't miss the small details.
⚠️ Warning: Do not use metal blades or knives! they can damage the plumes or puncture the battery, which will lead to a short circuit.
Turn off your smartphone and remove it. SIM-map|Make a backup copy of the data|Charge your phone to at least 30%|Prepare a workplace with good lighting|Check the availability of all tools-->
Step-by-step instructions for disassembling Redmi Note 8
The Redmi Note 8 starts by removing the back cover, and unlike the flagships, it's not on the latches, but is glued around the perimeter, and proceed carefully so that the antenna contacts are not damaged (thin metal stripes at the edges).
Step 1. Heat the body.
Turn the dryer on at minimum power (or set a temperature of 60-70°C at the thermo-air station). Warm up the edges of the back cover for 2-3 minutes, evenly driving the hairdryer around the perimeter. The glue will become softer, and the cover will be removed more easily.
Step 2. Remove the back cover
Insert a plastic blade into the gap between the lid and the body (better start at the lower left corner where the SIM card is located). Carefully drive the blade along the edge, gradually lifting the lid. If you feel resistance, warm up the place again with a hairdryer.
Step 3. Shutting down the battery
Once the lid is removed, first of all, disconnect the battery connector (it is located at the top, under the metal cover).
- Unscrew 4 screws that fix the metal plate.
- Put a plastic scapula on the connector and gently disconnect it.
Step 4: Dismantling the old battery
The battery is glued to the body. There are two ways to remove it.
- 🔥 Heated: Warm up the battery with a hairdryer (no higher than 80)°C!), then pull on the special ears (if any) or squirt with a spatula. The glue will soften and the battery will move away.
- 🧵 No heating: Stick the string under the battery and saw it back and forth, gradually separating the glue. It's longer, but safer.
After removing the battery, clean the case of glue residues with isopropyl alcohol. Do not use acetone or solvent - they can damage the plastic!
What to do if the battery is blown?
Installation of a new battery and assembly of the phone
Before installing a new battery, check:
- 🔌 Contacts of the connector for the presence of oxidation (clean with alcohol if necessary).
- 📏 Battery sizes – it should fit tightly into the designated place.
- 🔋 Voltage (multimeter) - should be 3.7-4.2 V.
Step 1. Connect the battery
Connect the new battery connector to the motherboard, and make sure it sits down until the end — if the contact is not tight, the phone won't turn on or will spontaneously shut down.
Step 2. Battery locking
Most new batteries come with adhesive backing. If you don't have one, use double-sided tape (like 3M 467MP). Stick the battery with a little pressing around the edges. Don't push the center, it can warp the cells.
Step 3: Assembly of the hull
Place the metal plate and twist the screws (don't pull!) Then return the back cover, starting at the top. Press it around the perimeter so that the glue catches. For reliability, you can warm the edges with a hairdryer (60°C) for 1-2 minutes.
Step 4. Checking.
Turn on the phone and check:
- 🔋 The level of charge (must correspond to the real one).
- ⚡ Charging speed (use the original power supply).
- 📱 Heating of the body (normally - up to 40)°C when charging).
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After replacing the battery, be sure to calibrate it: completely discharge the phone, then charge to 100% without interruption. Repeat the procedure 2-3 times to accurately display the charge level.
Frequent Mistakes and How to Avoid Them
Even with a careful replacement, you can make mistakes that will cause the phone to malfunction.
- Damage to the display plume, which passes under the battery and breaks easily when unwisely dismantled, always slam the battery on the opposite side of the plume.
- If the battery contact is not fully in the socket, the phone will spontaneously shut down. Check the socket with a magnifying glass.
- Using an incompatible battery. The batteries from the Redmi Note 7 or Note 8 Pro won't work, they have different connectors and sizes.
- If you solder the contacts (which is not required for normal replacement), do not hold the soldering iron for more than 2 seconds - you can melt the plastic.
If the phone is not switched on after replacement:
- Check the connection of all the plumes (especially the display and power buttons).
- Make sure the battery is properly connected (the connector must click).
- Try charging your phone with another charger (possibly the problem is the power supply).
⚠️ Warning: If the phone turns on after assembly but does not charge, check it out. USB-port for debris or bent contacts, often the problem is not the battery, but the connector.
How long will the new battery last?
The battery life depends on three factors:
- Battery quality: Original or certified (e.g. Baseus) last 2-3 years; cheap equivalents are 6-12 months.
- Operating conditions: Frequent overheating (games, sun), full discharges and charging with "cheap" reduces the life of the user.
- Calibration: If you don't calibrate the battery after you replace it, the power controller will not display the charge level correctly.
To extend the life of a new battery:
- 🔌 Use the original power supply (or certified with Quick Charge 3.0 support).
- 🌡️ Avoid overheating (do not play heavy games while charging).
- 🔋 Keep the charge level in the range of 20-80% (full discharges and 100% charging reduce the resource).
- 📴 Turn off background processes (in Settings) → Battery → Optimization).
If properly maintained, the new battery will last 500-800 charging cycles (that's about 2-3 years of active use), and if the capacity has dropped to 70% again after a year, the problem could be with the power controller on the motherboard.