Why the Redmi Note 4 battery fails and when to change it
Xiaomi Redmi Note 4 (codenamed mido) was released in 2017 and is still popular today for reliability and maintainability. However, even the most tenacious models, the battery degrades over time. If your device starts to run out in a few hours, turn off at 20-30% charge or overheat during charging, these are sure signs that the battery needs to be replaced.
The manufacturer claimed the battery life in 500-800 charging cycles, but in practice after 2-3 years, the capacity drops to 60-70% of the original 4100 mAh. The reasons are several: natural wear of lithium polymer cells, overheating during intensive use, the use of non-original chargers. Unlike flagships, where the battery is often soldered to the board, in the Redmi Note 4 it can be replaced independently - even without special skills.
The main challenge is that there are no screws on the back cover, and many users mistakenly think that the case is glued together, but it's actually fixed by latches and double-sided tape, and the right approach would allow you to open the smartphone without damage and install a new battery in 30 to 40 minutes.
What tools will be needed to replace
Before you start, prepare everything you need, and without the right tools, you risk damaging plumes, tearing off contacts, or scratching the body.
- 🔧 Plastic mediators or blades (2-3 pieces) - to separate the latches of the shell!
- 🔥 Dryer or thermo-air station - for softening the glue (temperature 60-80)°C) Even a household hair dryer at maximum power will work.
- 🧲 Suction cups help lift the lid after heating, you can use a glass suction cup or even a stationery holder.
- ⚡ New battery - original (article) MB-BL4100mAh) or a qualitative analogue (for example, from Baseus or Remax).
- 📏 Thin screwdriver or tweezers - to disconnect the battery plume from the motherboard.
- 🧴 Isopropyl alcohol (90%+) — to remove glue residues. Acetone or solvent cannot be used!
If you are disassembling a smartphone for the first time, we recommend you also purchase a repair kit (costs 300-500 rubles on AliExpress), which usually includes all the necessary mediators, a sucker and even a small magnet for screws (although Redmi Note 4 does not have them).
⚠️ Warning: Do not use knives, screwdrivers or other sharp objects to open the case! this is almost guaranteed to result in scratches on the plastic or damage to the fingerprint plume that runs under the lid.
How to choose a high-quality battery: original vs analogues
The choice of battery depends on how long your Redmi Note 4 will last after replacing. The original Xiaomi batteries cost more (1500-2000 rubles), but guarantee compatibility and long life. Analogs are cheaper (800-1200 rubles), but among them there are many fakes with low capacity.
When buying, pay attention to:
- 🔋 Capacity: Must be at least 4,000 mAh (original - 4100 mAh), batteries with declared 5000 mAh and above - almost always a fraud.
- 📦 Packaging - the original comes in a white box with a hologram, analogue - in a transparent blister with markings.
- 🔍 Contacts must be clean, without oxidation, and the battery board usually has the date of production and serial number.
- 🛡️ Protection against overheating – high-quality batteries have a thermosensor and charge controller.
| Parameter | Original battery | Quality analogue | Fake (low quality) |
|---|---|---|---|
| Capacity | 4100 mAh | 4000-4100 mAh | 3000-3500 mAh (overwhelming on packaging) |
| Price. | 1500–2000 ₽ | 800–1200 ₽ | 400–700 ₽ |
| Guarantee | 6–12 months | 3–6 months | Absent or 1 month |
| Term of service | 3-4 years | 2–3 years | 6–12 months |
Check the reviews before you buy. On AliExpress, look for stores with a rating of at least 98% and orders from 1000+. Pay attention to photos of real customers - often there you can see what the battery looks like live.
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Before installing a new battery, charge it to 30-50%, which will help the controller to properly calibrate the capacity in the first cycles of operation.
Step-by-step instructions: how to open the case without screws
The most important step is to carefully separate the back cover, and if you do this incorrectly, you can damage the fingerprint scanner plume or tear off the antenna contacts.
- Turn off your smartphone and remove it. SIM-This will prevent short circuits when you're working with the board.
- Heat the body with a hair dryer around the perimeter for 2-3 minutes. Keep the hair dryer at a distance of 5-7 cm to avoid melting the plastic. Pay special attention to the bottom part - there is more glue.
- With a suction cup, lift the lid from the lower left corner (near the USB-C connector). If there is no suction cup, you can gently tuck the mediator in, but without jerking.
- Move the mediator along the edge, alternately snapping the clamps. Start at the bottom, then move to the sides. The top (near the camera) opens last.
If the lid doesn't respond, reheat the problem area. Don't put too much force on the plastic, it can crack. When you hear the characteristic clicks of the clamps that are snapping, the lid will easily separate.
Make sure all latches are snapped.|Check if the fingerprint is tightened.|Check the case for cracks|Place the lid on a soft surface (for example, a napkin)-->
⚠️ Attention: The fingerprint scanner plume is very fragile, it attaches to the lid and connects to the board through the connector, if you pull the lid sharply, the plume will break, and the scanner will stop working.°.
Disconnecting the old battery and installing a new one
When the case is open, you'll see the battery glued to the back wall, held back by double-sided tape, and on top by a black protective film, and don't try to pull the battery out right away, because you risk tearing the contacts off or damaging the board.
Act on the algorithm:
- Take the battery plume off the motherboard, and it's under a little black lid (you can tweez it), and you can gently put a plastic scapula on the jack, and you can unplug it.
- Take the protective film off the battery. It's not glued very much, so just pull the corner.
- Push the battery with a plastic mediator on the side (where there are no board components) and slowly pull up. If resists, heat the phenomic part of the battery for 1-2 minutes.
- Remove the glue from the case and the new battery with isopropyl alcohol. Don't use acetone, it's corroding the plastic!
- Install a new battery starting at the top, make sure it's flat, free of distortion.
- Plug the plume back into the board. It should snap with a slight click.
Critically, before you plug in the plume, make sure that the contacts are free of dust or glue residue. Even a microscopic particle can cause a short circuit.
What to do if the battery is swelling?
Build a smartphone and the first charging
Once the new battery is installed, the Redmi Note 4 is assembled in reverse order.
- 🔌 Connect the fingerprint scanner plume to the board, make sure it's not bent or lided.
- 📱 Line the latches of the body before the final closure. Start at the top (near the camera), then click the sides.
- 🔥 Heat the edges of the lid with a hair dryer (30-40 seconds) and press tightly. This will help the glue to better grip.
Don't turn on the smartphone right away. Wait 10-15 minutes for the glue to cool and the lid to sit tightly in place. Then plug in the original charger and charge the battery to 100%. The first 2-3 charge/discharge cycles may seem fast - that's OK, as the controller calibrates the new battery.
Check the operation of all functions:
- 📶 Network and calls – make sure the antenna is not damaged.
- 🔍 Fingerprint scanner – if it doesn’t work, check the plume connection.
- 🔋 Charging – the smartphone should determine the percentage of charge without jumps.
(1) Correct connection of the battery plume.
(2) Integrity of contacts on the board (whether there is oxidation).
3) Charger (try another one).
In 90% of cases, the problem lies in poor contact plume.-->
Frequent Mistakes and How to Avoid Them
Even with a careful replacement, you can make mistakes that will cause the device to fail, and here are the most common mistakes and ways to prevent them:
| Mistake. | Effects of consequences | How to avoid |
|---|---|---|
| A sharp opening of the lid | Fingerprint plume break | Heat the hair dryer and open slowly, from the corner |
| Use of metal tools | Scratches on the case, damage to the board | Only work with plastic mediators |
| Incomplete shutdown of battery plume | Short circuit when working with the fee | Check the disconnection of the connector visually |
| Installation of the battery with distortion | Bad contact, quick discharge. | Level the battery before gluing |
If your smartphone gets overheated after you replace it, you may have damaged the heat paste on the processor, which means you need to re-disassemble the device and apply a new paste (such as the Arctic MX-4).
Another common problem is that the charge display is incorrect (e.g., jumps from 50% to 1%), which means that the battery controller is not calibrated.
- Completely discharge the smartphone before turning it off.
- Charge to 100% without interruption.
- Repeat the cycle 2-3 times.