About this replacement
Lenovo A330E / A399 / A3500 Series — 3.7V Li-ion Replacement Battery (BL239)
This is a 3.7V, 1900mAh Li-ion cell replacing the OEM BL239 battery. It fits the Lenovo A330E, A399, A3500, and A3500-HV smartphones. Voltage and capacity match the original spec exactly — no modifications needed to install it.
- A330E / A399 / A3500 platform fit: All four models share the same battery bay dimensions, 3.7V nominal voltage rail, and BL239 connector pinout. The BMS handshake protocol is consistent across the series, so the fuel gauge IC on each device reads this cell without modification.
- Bench tested on actual hardware: We cycled this cell on an A3500 unit and monitored BMS communication throughout charge and discharge. The protection circuit engaged correctly at low-voltage cutoff, and the charge IC accepted the cell without triggering an incompatibility error.
- Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC build an accurate discharge curve against the new cell before high-current charging begins on an uncalibrated coulomb counter.
Sudden shutdown at 20–30% on the A330E after a cell swap
A fresh cell has a slightly different voltage-discharge curve than the depleted original it replaced. The A330E's fuel gauge IC still holds the old curve in memory and misjudges remaining capacity. When the modem or display draws a current spike, the cell voltage dips below the BMS cutoff threshold — even though the percentage shown looks safe. The fix is one full uninterrupted discharge down to auto-shutoff, then a full charge without interruption, which forces the coulomb counter to resync to the new cell's actual curve.
Phone reports wrong battery percentage after BL239 replacement
The fuel gauge IC on these Lenovo devices calibrates its percentage readout against charge and discharge history stored from the old cell. A new cell resets that baseline, so percentage readings can jump, stall, or read 100% well before a full charge completes. This is not a faulty cell — it is the coulomb counter working from stale data. Run two full discharge-charge cycles with the screen on and no charge interruptions; by the end of the second cycle the IC recalibrates and percentage tracking stabilises.