Sendo X 3.7V Replacement Battery 8M24-0H000-00000 1250mAh

Sendo X — 3.7V Li-ion Replacement Battery (8M24-0H000-00000)

This is a 3.7V, 1250mAh Li-ion replacement cell for the Sendo X smartphone. It matches the OEM part number 8M24-0H000-00000 and slots directly into the Sendo X battery bay. Capacity is 4.63Wh — identical to the original specification.

• Sendo X platform fit: The Sendo X ran a Symbian-based stack with a single Li-ion cell at 3.7V nominal. This replacement matches that voltage rail and the original connector pinout, so the device power management IC sees no mismatch on startup.
• Bench tested on actual hardware: We cycled this cell through a full discharge-charge sequence and monitored BMS handshake behaviour. The protection circuit triggered correctly at both the low-voltage cutoff and the charge termination threshold — no false trips recorded.
• Fuel gauge recalibration on first use: On first installation, disable any fast-charge mode and run one complete discharge-charge cycle before normal use. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging pushes current into an uncalibrated baseline.

Sudden shutdown at 20–30% on the Sendo X after a cell swap

The Sendo X fuel gauge IC was calibrated against the original cell's internal resistance and voltage-discharge curve. A new cell has a different impedance profile, so the IC misjudges the remaining capacity. Under load — screen on, radio active — the cell voltage dips below the shutdown threshold before the reported percentage reaches zero. One full discharge-charge cycle resets the coulomb counter and closes that gap. Until then, expect the phone to cut out anywhere between 15% and 35%.

Sendo X shows wrong battery percentage after replacement

The fuel gauge IC stores learned discharge data from the old cell. A fresh cell with a slightly different discharge curve causes the IC to report percentage values that don't match actual charge state — often jumping erratically or reading full charge too early. The fix is a single uninterrupted discharge down to automatic shutdown, followed by a full charge to 100% without interruption. After that cycle, the IC recalibrates its internal model against the new cell's voltage curve and percentage reporting stabilises.