Philips Xenium X818 Replacement Battery AB3000LWMT 3.8V

Philips Xenium X818 — 3.8V Li-Polymer Replacement Battery (AB3000LWMT)

This is a 3.8V, 2800mAh Li-Polymer cell built to the AB3000LWMT spec for the Philips Xenium X818 smartphone. It replaces the original pouch cell when the existing battery no longer holds a charge, swells, or causes unexpected shutdowns. Dimensions are 70.00 × 58.10 × 4.10mm — measure your current cell before ordering if you are unsure.

• Xenium X818 fitment: The X818 uses a removable pouch cell with a three-pin connector that carries both charge current and the thermistor signal. The AB3000LWMT pinout matches this exactly — swapping a non-matched connector will break the temperature reporting loop and cause the charge IC to reject the cell.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on an X818 mainboard. The BMS handshake completed on the first cycle, the charge IC accepted current without fault codes, and voltage held steady under active screen and modem load.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge to automatic shutdown, then charge uninterrupted to 100% before enabling fast charge. This gives the fuel gauge IC one clean cycle to map the new cell's discharge curve — skipping it causes the percentage counter to read inaccurately for several weeks.

Why the Xenium X818 reports wrong battery percentage after a cell swap

The X818 uses a coulomb-counter-based fuel gauge IC that stores a learned discharge curve from the original cell. When a new cell is fitted, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The IC keeps using the old curve until it completes at least one full discharge-to-charge cycle on the new cell. Until recalibration happens, the display may show 40% remaining while the cell is actually near cutoff voltage — or show 100% before the cell is genuinely full.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff issue, not a faulty cell. When the modem transmits or the screen brightness spikes, instantaneous current draw pulls the cell voltage below the BMS cutoff threshold — even though the fuel gauge still shows charge remaining. It happens most often in the first few cycles before the gauge IC has recalibrated. Run two full discharge-charge cycles without interruption and check that the cell voltage reads at least 3.75V when the phone reports 30% — if it reads below 3.6V at that point, the calibration cycle is incomplete.