Redmi Note 5 BN35 Compatible Battery 3.85V 3200mAh Li-Po

Redmi 5 — 3.85V Li-Polymer Replacement Battery (BN35)

This is a 3200mAh, 3.85V lithium-polymer cell built to the BN35 specification. It fits the Redmi 5 smartphone. Swap it in when the original cell no longer holds charge, swells, or causes unexpected shutdowns.

• Redmi 5 fit: The Redmi 5 uses a fixed connector pinout tied to the BN35 form factor — same flex ribbon tab, same 78.72 × 63.10 × 3.50mm footprint, same BMS handshake with Qualcomm's PMIC on the board. No modifications needed at the hardware level.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Redmi 5 unit. The BMS accepted the cell without fault flags, charge termination fired correctly at 4.35V, and the PMIC did not trigger over-voltage protection on the first cycle.
• First-cycle fuel gauge reset: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before fast-charge current is applied to an uncalibrated cell.

Why the Redmi 5 reports wrong battery percentage after a cell swap

The fuel gauge IC on the Redmi 5 builds its charge model by tracking coulombs against a stored discharge curve from the original cell. When a new cell goes in, that curve no longer matches, so the reported percentage drifts from the real state of charge. The IC needs at least one full discharge cycle — from 100% down to auto-shutdown — followed by an uninterrupted charge to 100% to rewrite its reference data. Until that cycle completes, readings between 30% and 70% are the least accurate. After one full cycle, the gauge corrects itself without any app or software intervention.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display pulls a high-current burst and the cell voltage drops below the BMS cutoff threshold — even though the reported percentage looks safe. A freshly installed cell with an uncalibrated fuel gauge makes this worse because the IC may show 25% when the actual state of charge is already near the low-voltage cliff. Run that first full discharge cycle without interruption so the coulomb counter anchors to the real cell capacity. If shutdowns continue after two full cycles, check that the battery connector flex tab is fully seated — a partial connection raises contact resistance and amplifies voltage sag under load.