TCL J720 Replacement Battery TLi019B2 3.8V 2000mAh

TCL J720 / J726T Series — 3.8V Li-ion Replacement Battery (TLi019B2)

This is a 3.8V, 2000mAh (7.6Wh) Li-ion cell sourced as a direct replacement for the TCL J720, J726T, J738M, J730U, and compatible variants. It fits the internal battery slot using the same connector and cell dimensions (70.75 × 51.20 × 4.70mm) as the original TLi019B2. If the original cell is swelling, failing to hold charge, or dropping off quickly under load, this is the cell to replace it with.

• J720 / J726T series fitment: These models share the same battery bay geometry, connector pinout, and BMS handshake protocol. One cell covers the full compatibility range listed — no adapter or modification needed.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on compatible hardware. The BMS accepted charge from both standard 5V and the device's native charge IC without triggering fault flags or thermal cutoff.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This allows the fuel gauge IC to map the new cell's discharge curve before the charge IC begins pushing higher current into it.

Sudden shutdown at 20–30% on the TCL J720 after a cell swap

This is a voltage cliff issue, not a capacity fault. When the modem radio or display fires a high-draw burst, the new cell's voltage drops momentarily below the BMS cutoff threshold — even though the OS gauge still reads 20–30%. The fuel gauge IC is still calibrated to the old cell's internal resistance curve, so its percentage estimate is off. Run one full discharge cycle down to automatic shutdown, then charge to 100% without interruption — this resets the coulomb counter against the new cell's actual curve.

OS battery percentage jumping erratically after replacement

The Android fuel gauge IC stores a learned discharge model from the previous cell. When a new cell goes in, the stored model no longer matches actual cell behaviour, so percentage readings jump or stall at fixed points. This is not a fault with the replacement cell — it is the coulomb counter recalibrating. Let the phone discharge to auto-shutdown naturally, then charge uninterrupted to 100%. Most TCL devices stabilise the percentage readout within two full cycles.