Xiaomi Mi 9T Replacement Battery BM4G 3.85V 4000mAh
This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.
WECARE5
Check that your old battery model number and device model to match our description. This makes sure they work together.
We ship your order same day if you buy it before 4 PM EST.
Xiaomi Mi 9T Replacement Battery BM4G 3.85V 4000mAh - is backordered and will ship as soon as it is back in stock.
Let customers speak for us
Send Your Battery Photo
Expert Technician Help
Snap a photo or video of your battery and send it to us. We'll identify the exact replacement—fast and hassle-free. Our team has helped thousands of customers find the right battery quickly and easily.
POST YOUR BATTERY IMAGE
Product & Solutions Expert
✉ sales@batteryweb.com
Battery Care Tips
Battery Care Tips
🔹 Getting Started
Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.
🔹 Keep It Healthy
Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.
Delivery and Shipping
Delivery and Shipping
🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.
Disclaimer
Disclaimer
⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.
🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Xiaomi Mi 9T Replacement Battery BM4G 3.85V 4000mAh - is backordered and will ship as soon as it is back in stock.
Voltage
3.85V
Amp
4000mAh
Xiaomi Mi 9T / Mi 9T Pro — 3.85V Li-Polymer Replacement Battery (BM4G)
This is a 3.85V, 4000mAh (15.4Wh) lithium-polymer cell for the Xiaomi Mi 9T and Mi 9T Pro. OEM part number BM4G. It fits the pop-up camera variants of the Mi 9T lineup — both share the same battery bay, connector, and BMS handshake protocol.
- Mi 9T and Mi 9T Pro compatibility: Both models run the same battery bay geometry and use the same four-pin connector with identical BMS communication. One cell fits both — no hardware modification needed.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on a Mi 9T unit. The BMS accepted the cell on first connection, charge termination triggered correctly at 4.4V, and no thermal flags appeared during the fast-charge phase.
- First-cycle fast charge protocol: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.
Sudden shutdown at 20–30% on the BM4G replacement cell
This happens when the fuel gauge IC is still calibrated to the old cell's discharge curve. A fresh cell has a steeper voltage cliff under modem or display load — the phone reads 25% but the actual cell voltage drops below the BMS cutoff threshold under that load spike. The BMS trips and the phone shuts down hard. One full discharge-charge cycle without fast charging corrects the coulomb counter and the shutdowns stop.
Phone not powering on after the BM4G sat in storage
Lithium-polymer cells stored below approximately 2.5V per cell trigger BMS lockout — the protection circuit opens and blocks current flow to prevent damage. A standard charger cannot restart the phone in this state. Connect the phone to a 5V/1A USB-A charger — not a fast charger — and leave it for 20–30 minutes without attempting to power on. The charge IC delivers a low-current trickle that brings the cell above the BMS re-enable threshold, typically around 2.9V, after which normal charging resumes.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Xiaomi
- Manufacturer: CS
- Series: Standard
- Color: Black
- Product Type: Li-Polymer
- Battery Type: Li-Polymer
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The Mi 9T is shutting off randomly at around 25% battery — why does this happen with a new cell?
The fuel gauge IC inside the Mi 9T was calibrated to the discharge curve of the original worn cell, not the new one. A fresh cell has a sharper voltage drop under heavy loads like the modem or screen — the phone reads 25% but the actual voltage collapses below the BMS trip point. Run one full discharge down to automatic shutdown, then charge to 100% without fast charging enabled. That single cycle re-anchors the coulomb counter to the new cell and the premature shutdowns stop.
Fast charging stopped working after I swapped in the BM4G — the phone just charges slowly now.
On the first cycle after a cell swap, the Mi 9T's charge IC sometimes withholds the proprietary fast-charge handshake until it has verified the new cell's impedance profile. This is normal behaviour, not a fault with the cell. Complete one full slow charge to 100%, then discharge naturally. On the next charge cycle the fast-charge protocol re-engages. If it still does not appear after two full cycles, check that the USB cable supports the required current — a cable-side resistance issue mimics the same symptom.
The battery percentage is jumping around erratically — it shows 60%, then drops to 41%, then climbs back up.
Erratic percentage readings after a cell replacement are a fuel gauge IC recalibration issue, not a fault with the new cell. The Mi 9T's gas gauge uses a coulomb counter that was tuned to the capacity fade pattern of the old battery — the new cell's fuller capacity throws off its state-of-charge estimates. Discharge the phone completely until it powers off on its own, then charge uninterrupted to 100% with fast charging off. After one clean full cycle the gauge stabilises and percentage readings become consistent.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
Related Products
Engineered for Performance. Built to Last.
Check out our top-rated selection of reliable products built to last. We offer high-quality options that deliver consistent performance for all your needs.
-
Up to 21% offNew arrival
BatteryWeb
OPPO A58 Replacement Battery BLPA19 3.9V 4600mAh
0.27 lb
Sale priceFrom $30.99 USD Regular price $38.99Unit priceIn stock (60 units) -
-
Up to 21% offNew arrival
BatteryWeb
Oppo BLPA05 Reno 10 5G Replacement Battery 3.89V 5000mAh
0.25 lb
Sale priceFrom $30.99 USD Regular price $38.99Unit priceIn stock (66 units) -
-
Up to 19% offNew arrival
BatteryWeb
BN5F Xiaomi Redmi Note 12 Pro Compatible Battery 3.82V 5000mAh
0.26 lb
Sale priceFrom $38.99 USD Regular price $47.99Unit priceIn stock (66 units) -
-
Up to 19% offNew arrival
BatteryWeb
Redmi A2 Replacement Battery BN5F 3.82V 5000mAh
0.26 lb
Sale priceFrom $38.99 USD Regular price $47.99Unit priceIn stock (66 units) -
-
Up to 20% offNew arrival
BatteryWeb
Huawei P40 Pro Replacement Battery HB536378EEW 3.85V 3750mAh
0.24 lb
Sale priceFrom $36.99 USD Regular price $45.99Unit priceIn stock (12 units) -
-
Up to 20% offNew arrival
BatteryWeb
SB2000 Schok Flip SC3218T Replacement Battery 3.8V 2100mAh
0.14 lb
Sale priceFrom $40.99 USD Regular price $50.99Unit priceIn stock (174 units) -
-
Up to 20% offNew arrival
BatteryWeb
Bea-fon M6s Premium Replacement Battery 3.85V 4000mAh
0.23 lb
Sale priceFrom $43.99 USD Regular price $54.99Unit priceIn stock (66 units) -
-
Up to 20% offNew arrival
BatteryWeb
AT&T EABF22206A Replacement Battery 3.85V 3600mAh
0.22 lb
Sale priceFrom $43.99 USD Regular price $54.99Unit priceIn stock (63 units) -
