Highscreen Spark 3.7V 1300mAh Replacement Battery

Highscreen Spark — 3.7V Li-ion Replacement Battery

This 3.7V, 1300mAh Li-ion cell replaces the original battery in the Highscreen Spark smartphone. It fits the Spark directly and restores power when the original cell can no longer hold a usable charge. Capacity is 4.81Wh, matching the stock specification.

• Highscreen Spark fit: The Spark uses a compact 3.7V single-cell configuration with a low-current BMS. This replacement matches that voltage rail and connector pinout, so the charge IC communicates with the new cell without flagging a fault on boot.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a 3.7V Li-ion bench rig. The BMS held cutoff at the correct upper and lower voltage thresholds, and charge current tapered cleanly at full capacity without tripping a protection fault.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle at standard current. This lets the Spark's fuel gauge IC map the new cell's discharge curve before the OS begins reporting accurate percentages.

Why the Highscreen Spark reports wrong battery percentage after a cell swap

The Spark's fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The OS reads voltage from the fuel gauge and converts it to a percentage using the old data, so reported figures can run 10–20% off actual state of charge. One full discharge below 10% followed by a complete charge cycle forces the coulomb counter to recalibrate against the new cell.

Sudden shutdown at 20–30% on the Highscreen Spark

This happens when the cell voltage drops sharply under load — typically during a cellular data burst or screen-on peak draw — faster than the fuel gauge expects. The phone shuts down before the reported percentage reaches zero because the cell cannot sustain voltage above the BMS cutoff threshold under that current spike. It is not a cell defect; it is the fuel gauge working from a miscalibrated baseline. Run one full discharge-charge cycle and let the reported percentage stabilise above 5% before the next charge — the shutdown threshold should move back to below 10%.