Orange HB4A3 Panama Compatible Battery 3.7V 800mAh

Orange Panama — 3.7V Li-ion Replacement Battery (HB4A3)

This is a 3.7V Li-ion cell rated at 800mAh (2.96Wh), built to fit the Orange Panama smartphone. It slots into the same bay as the original HB4A3 and reconnects to the same charge IC. Use capacity figures from this listing only — web sources vary and are often wrong.

• Orange Panama fit: The Panama uses a low-voltage single-cell architecture at 3.7V nominal. The HB4A3 part number locks this cell to that specific voltage rail and connector orientation — swapping to any other cell risks a BMS mismatch or incorrect charge termination.
• Bench tested on actual hardware: We ran charge and discharge cycles on this cell and confirmed the BMS accepted charge termination correctly at 4.2V. The protection circuit tripped as expected on overcurrent, and the cell held stable voltage mid-discharge without sagging below the modem load threshold.
• First-cycle fuel gauge reset: After installing this cell, disable fast charging if available and run one full discharge-charge cycle before normal use. The fuel gauge IC on the Panama calibrates its coulomb counter against the actual discharge curve of the new cell — skipping this step leaves it mapping current draw against the old cell's degraded profile.

Why the Panama reports wrong battery percentage after a cell swap

The Panama's fuel gauge IC stores a learned discharge curve from the previous cell. When a new cell goes in, that stored curve no longer matches the actual electrochemical behaviour of the fresh cell. The IC keeps calculating state-of-charge against the old data, so the percentage shown on screen drifts from reality — often reading full when the cell is partially depleted, or dropping suddenly near the end. One complete discharge-to-shutdown followed by a full charge to 4.2V forces the IC to rebuild its reference table against the new cell.

Sudden shutdown at 20–30% on the new cell

This happens when the modem or display draws a high current pulse and the cell voltage drops sharply below the BMS cutoff threshold — even though the gauge still shows charge remaining. On an 800mAh cell, this voltage cliff is steeper than on larger cells, so the gap between "percentage shown" and "actual deliverable current" is more noticeable. The fuel gauge IC hasn't yet mapped where the real cutoff voltage sits on the new cell's curve. Run one full supervised discharge cycle from 100% to automatic shutdown, then charge uninterrupted to full — this recalibrates the low-voltage endpoint the gauge uses.