TCL 40 SE Replacement Battery TLp049FA 3.87V 4900mAh

TCL 40 SE / T610E2 / T610K — 3.87V Li-Polymer Replacement Battery (TLp049FA)

This is a 3.87V, 4900mAh (18.96Wh) lithium-polymer cell that fits the TCL 40 SE, T610E2, T610K, and T610K2. It replaces the original TLp049FA when the factory cell can no longer hold voltage under screen or modem load. Dimensions are 92.00 × 65.00 × 3.50mm — measure your existing cell before ordering if the chassis has been repaired before.

• TCL 40 SE series compatibility: The T610E2, T610K, and T610K2 share the same 3.87V power rail, connector pinout, and BMS handshake as the 40 SE. One cell covers all four variants because the charge IC accepts the same voltage thresholds and NTC thermistor curve across the lineup.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the T610K2. The BMS held charge termination at 4.40V and triggered low-voltage cutoff cleanly at 3.0V. No mid-cycle faults, no thermal flags on the charge IC.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This gives the coulomb counter a clean reference point against the new cell's actual discharge curve before high-current charging begins on an uncalibrated gauge.

Sudden shutdown at 20–30% on the TCL 40 SE after a cell swap

This happens because the fuel gauge IC still holds the old cell's discharge curve in memory. A degraded original cell had a steep voltage cliff at low state-of-charge — the gauge learned that cliff. The new cell holds voltage further into discharge, but the IC cuts power early based on stale data. One full discharge cycle — down to automatic shutdown, then a full charge — resets the coulomb counter and eliminates the early cutoff.

USB fast charge not activating after battery replacement

On the first charge cycle after installation, the charge IC may not negotiate the fast-charge protocol with the new cell's BMS. This is normal — the IC defaults to standard 5V/1A until it confirms the cell's temperature and impedance are within range. Charge once at standard rate using the stock cable and charger. Fast charge typically activates automatically from the second cycle onward once the BMS clears its initialisation flags.