Redmi Note 6 BN46 Compatible Battery 3.85V 3800mAh

Redmi Note 6 / Note 8 Series — 3.85V Li-Polymer Replacement Battery (BN46)

The BN46 is a 3800mAh Li-Polymer cell rated at 3.85V, built to replace the original battery in the Redmi Note 6, Note 8, Note 8T, and M1810F6LG. These phones share the BN46 form factor and connector pinout, making one cell compatible across the entire lineup. Install this when the existing cell no longer holds a usable charge or causes unexpected shutdowns.

• Note 6 / Note 8 / Note 8T platform fit: These models run the same BN46 connector layout and BMS handshake protocol. The voltage rail and thermistor pin position are identical across the group, so one cell covers all listed variants without modification.
• Bench tested on actual hardware: We cycled this cell on a Note 8 unit through charge and discharge under screen-on and modem-active load. The BMS accepted charge current correctly and the protection circuit tripped as expected at the low-voltage threshold — no false cutoffs during the test runs.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one full discharge down to automatic shutdown, then charge to 100% uninterrupted. This gives the coulomb counter IC a clean reference curve for the new cell before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the BN46 replacement cell

This is a voltage cliff issue. The fuel gauge IC still holds the discharge curve from the old, degraded cell, so the percentage reading no longer matches actual cell voltage. Under screen or modem load, voltage drops faster than the stale curve predicts — and the protection circuit cuts power before the displayed percentage reaches zero. One full discharge-to-shutdown cycle followed by an uninterrupted charge to 100% resets the coulomb counter to the new cell's actual curve. After that cycle, shutdowns at inflated percentages stop.

USB fast charge not activating after battery replacement

The Note 8 and Note 8T use Qualcomm Quick Charge handshake over the USB port. On the first charge after a cell swap, the BMS on the new cell may not pass the thermal and voltage-ready signals the charge IC expects before unlocking high-current mode. The charger falls back to standard 5V input as a precaution. Charge the phone once at standard speed to full capacity — on the second charge cycle, the BMS signals are stable and fast charging resumes normally at the expected input voltage.