Replacement of the battery with Xiaomi Mi 9T: Full guide to photo and video

Xiaomi Mi 9T

Redmi K20

4000 mAh

1 500–3 000 ₽

In this article, you will find a step-by-step photo instruction, a list of tools you need, tips for choosing the original battery and answers to frequent questions. We will also tell you how to check battery wear before replacing and avoid the typical mistakes that may cause the smartphone to stop turning on.

⚠️ Replacement of the battery with Mi 9T It requires care, and you have fragile plumes and adhesive tapes inside the case, and if you've never taken your smartphone apart, you can work out on an old device or trust the professionals to do the work.

The average replacement time for beginners is 40 to 60 minutes, for power users it's 20 to 30 minutes. Ready to start? Then let's go!

How to check the wear of the battery before replacing

Before you buy a new battery, make sure it’s the problem.Here are 3 ways to diagnose battery wear on Xiaomi Mi 9T:

🔹 Through the smartphone menu:

1. Go to Settings. → The phone. → Battery status.
2. If it's below 80 percent of the original 4,000 mAh (less than 3200 mAh), it's time to change the battery.

🔹 Using the AccuBattery app (Android):

🔹 By indirect indications:

• ⚡ The smartphone turns off at 15-30% charge and turns on only from charging.
• 🔋 Battery discharges by 20-30% per hour in standby mode (without active use).
• 🔌 The phone does not hold a charge even after full charging (for example, 100% → 0% in 3-4 hours).
• 🌡️ The body heats up in the battery area for no apparent reason.

If you know at least 2-3 items from the list, replacing the battery is justified, otherwise the problem may lie in the software (for example, background processes) or the charger.

What tools are needed to replace

For self-replacement of the battery on Mi 9T Prepare the next set of tools, and without them, the risk of damaging your smartphone increases dramatically:

🔧 You'll need some extra:

• 🧲 Magnetic mat - so as not to lose screws (can be replaced with a sheet of paper and tape).
• 📦 Container for screws - for sorting fasteners by size.
• 🔦 Lupe or table lamp - to work with small details.

⚠️ Warning: Do not use metal blades or knives to separate the lid - they will scratch the body and may damage the plumes under the screen.Plastic mediators are safer but require care.

If you don’t want to buy the tools separately, take a ready-made smartphone repair kit (costs from 300). ₽ It's on AliExpress or Citilinka, and it already includes shoulder blades, screwdrivers and tweezers.

What battery to choose for Xiaomi Mi 9T

Original battery for the Mi 9T markable BM47 and capacity of 4000 mAh (nominal voltage) 3.85V). When choosing a replacement, pay attention to:

🔋 Type of battery:

• ✅ Original (OEM) — manufacturer ATL (Amperex Technology Limited. Cost: 1,200–1,800 ₽. Guaranteed fits in size and connector, but can be sold without adhesive base.
• ⚠️ The analogue of high quality - brands Baseus, Remax, Patona. Price: 800-1 200 ₽. Often completed with glue strips and tools.
• ❌ No-name battery (unlabeled) - risk of low capacity or bloating. Cost from 500 ₽, but the service life rarely exceeds 6 months.

📏 Dimensions and connectors:

• Length × width × thickness: ~148 × 70 × 3.5 mm (tolerance) ±0.5 mm).
• The connector should be JST 1.0 2P (two-pin, white).

🔍 Where to buy:

• 🛒 Xiaomi’s official service centers are original batteries, but the price is higher.

Critical: Check the seller's reviews before buying! Counterfeiting is often sold under the guise of originals, and its actual capacity can be 30-40% lower than claimed.

💡

If you choose between the original and the analog, prefer the former - even if it is more expensive. Cheap batteries often inflate after 3-6 months, which can damage the screen or motherboard.

Step-by-step instructions for replacing the battery

Now, to the most critical stage, follow the instructions carefully so that no plumes or contacts are damaged.

🛠️ Step 1: Turn off your smartphone and remove it. SIM-map

• 🔘 Press the power button and select "Switch off».
• 📱 Get the tray for you. SIM-card with a paper clip (hole on the right).

🔥 Step 2: Heat the back cover

• 🔥 Turn on the dryer at medium power and warm up the edges of the cover for 2-3 minutes.
• ⚠️ Don't overheat! Temperatures should not exceed 60-70.°C (touch should be warm but not scalding).

📱 Step 3: Separate the lid

• 🧲 With a suction or plastic spatula, gently pull the lid from the lower edge (near the connector). USB-C).
• 🔧 Swipe around the perimeter, separate the lid, and if you feel resistance, warm up the area again.

⚠️ Attention: Under the lid are the fragile plumes of the fingerprint scanner and antennas. Don't pull the lid sharply - first make sure it's receded around the perimeter.

🔧 Step 4: Unscrew the screws

• ⚡ Screwdriver. T3 twist 10 screws fixing the metal plate (they are of different lengths - remember the location!).
• 🧲 Remove the plate and put it together with the screws on the magnetic mat.

🔌 Step 5: Disconnect the plumes and battery

• 📱 Tweez gently disconnect the battery connector (white connector next to the motherboard).
• ⚡ Put the adhesive tapes under the battery and pull the "tongues" (if there are any).If the tapes aren't, use a plastic shoulder blade to separate the battery from the housing.

🆕 Step 6: Install a new battery

• 🔋 Check to have a sticky base on the new battery (or stick double-sided scotch yourself).
• 📱 Connect the connector and put the battery in place, slightly pressed.

🔧 Step 7: Build a Smartphone

• ⚡ Twisting the screws of the metal plate (do not tug over!).
• 🧲 Stick the back cover, warming it with a hair dryer for better fixation.

✅ Step 8: Check the performance

• 🔌 Connect the charger and make sure the phone is charging.
• 📱 Turn on your smartphone and check your settings. → Battery status.

Battery connector disconnected|All screws are in place.|No foreign objects inside the body|Adhesive tapes removed or replaced-->

Common Mistakes and How to Avoid Them

Even with a careful replacement, beginners often make mistakes that damage the smartphone or quickly wear out the new battery.

🔥 1. Overheating of the lid by a hairdryer

• ❌ Error: Using a hair dryer at maximum power or prolonged heating (more than 5 minutes).
• ✅ Solution: Keep the dryer 10-15 cm away from the body and warm in short intervals (30 seconds heating, 10 seconds break).

🔧 2. Confusion with screws

• ❌ Error: Installation of long screws in spaces for short (risk of damage to the motherboard!).
• ✅ Solution: Spread out the screws in groups on a magnetic mat or sign their location.

🔋 3. Damage to plumes

• ❌ Error: Sharp separation of the cover without checking for the presence of glued plumes.
• ✅ Solution: Before removing the cover completely, make sure it is not connected to the body by flexible cables (especially in the fingerprint scanner area).

⚡ 4. Incorrect battery connection

• ❌ Error: Connecting the battery connector "blindly", without checking polarity.
• ✅ Solution: There is a marking on the connector and motherboard + And – combine them before connecting.

📱 Ignoring calibration

• ✅ Solution: After replacing, fully discharge the phone, then charge to 100% without interruption. Repeat the process 2-3 times.

⚠️ Note: If the smartphone does not turn on after replacement, check:

How long will the new battery last and how to extend its life

Battery life on Xiaomi Mi 9T It depends on the quality of the battery, the operating conditions and the charging mode:

🔌 How to extend the life of the battery:

• 🔌 Use an original or certified charger (power) 18W for Mi 9T).

📊 Signs that the battery is degraded again:

• ⚡ Battery life reduced by 30% or more compared to the “fresh” replacement.
• 🔋 The phone heats up when charging more than usual.
• 📉 The discharge schedule in AccuBattery became uneven (sharp jumps in percentages).

💡

Regular battery calibration (every 2-3 months) helps to reset power controller errors and prolong battery life.

Frequent questions about replacing the battery with Xiaomi Mi 9T