Alcatel 1B 2020 TLi028C1 Replacement Battery 3.85V 2850mAh

Alcatel 1B 2020 / OT-5002 Series — 3.85V Li-ion Replacement Battery (TLi028C1)

This is a 3.85V, 2850mAh Li-ion cell replacing the original TLi028C1 in the Alcatel 1B 2020 and OT-5002 series smartphones. It fits variants including the OT-5002A, OT-5002D, and OT-5002F. The physical dimensions match the stock cell: 96.20 × 42.15 × 4.60mm.

• OT-5002 variant compatibility: The OT-5002A, OT-5002D, and OT-5002F share the same battery bay dimensions, connector pinout, and BMS handshake protocol. All three accept the TLi028C1, TLi028C7, and TLi028D7 part numbers interchangeably — same voltage rail, same NTC thermistor line.
• Bench tested on actual hardware: We cycled this cell on the OT-5002 platform and monitored BMS communication across charge, discharge, and modem-load spikes. The protection circuit responded correctly to over-current events and held the voltage rail stable under screen-on plus LTE load.
• First-cycle fast charge tip: 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 high-current charging pushes amps into an uncalibrated cell.

Why the Alcatel 1B 2020 reports wrong battery percentage after a cell swap

The fuel gauge IC on the 1B 2020 stores a learned discharge curve for the original cell in non-volatile memory. When a new cell goes in, that stored curve no longer matches the new cell's actual voltage-to-capacity relationship. The gauge then maps voltage readings against the wrong reference, producing percentage readings that are off by 10–25%. One complete discharge cycle — run the phone down to automatic shutdown, then charge to 100% uninterrupted — forces the coulomb counter to relearn against the new cell. After that cycle, percentage accuracy returns to normal.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops below the load threshold faster than the fuel gauge expects — a voltage cliff. Under combined modem, screen, and CPU load, the cell's internal resistance causes a sharp voltage sag that trips the BMS under-voltage cutoff before the reported percentage reaches zero. It is not a faulty battery; it is an uncalibrated gauge reading a fresh cell. Run two full discharge-charge cycles without interruption. By the second cycle the fuel gauge IC has enough data to shift the low-battery cutoff warning to the correct voltage point — typically around 3.5V per cell.