BL261 Lenovo K5 Note Replacement Battery 3.8V 3400mAh

Lenovo K5 Note — 3.8V Li-Polymer Replacement Battery (BL261)

This is a 3400mAh (12.92Wh) Li-Polymer replacement battery for the Lenovo K5 Note smartphone. It fits the K52t38, Lemon K5 Note Dual SIM TD-LTE, and A7020a48 variants. Voltage is 3.8V nominal — matching the original BL261 specification.

• K5 Note variant coverage: The K52t38, A7020a48, and Lemon K5 Note TD-LTE all share the same battery bay dimensions and BMS connector pinout, so one cell covers all four model numbers. The BL261 part number is the key identifier — confirm it on your original battery before ordering.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a K5 Note unit. The BMS accepted charge handshake normally, held voltage within spec across the discharge curve, and the protection circuit tripped cleanly at low-voltage cutoff without requiring a manual reset.
• Fuel gauge recalibration on first install: On first use after fitting this cell, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the K5 Note after a cell swap

The K5 Note's fuel gauge IC retains the discharge curve of the old, degraded cell in its coulomb counter memory. When a new cell is fitted, the IC still uses that old curve to estimate remaining capacity. Under modem or display load, the new cell's actual voltage drops faster than the IC expects at that percentage, triggering a low-voltage shutdown before the gauge reads zero. One full discharge-charge cycle at standard rate clears the calibration offset. After that cycle, the percentage readings track the new cell's curve correctly.

Phone not powering on after BL261 cell arrived fully discharged from storage

Li-Polymer cells shipped or stored for extended periods can drop below the BMS lockout threshold — typically under 2.5V per cell. When voltage falls that low, the protection circuit opens and blocks normal charge current entirely. The phone appears completely dead and the charging indicator may not appear. Connect to a wall charger — not a PC port — and leave it for 20–30 minutes without pressing the power button. The charge IC on the K5 Note will trickle current through the BMS at a recovery rate; once cell voltage climbs above 2.7V, the BMS closes and normal charging resumes.