Olympia Brio DRTEL-4D-01 3.7V Replacement Battery

Olympia Brio — 3.7V Li-ion Replacement Battery (DRTEL-4D-01)

This is a 3.7V, 1200mAh Li-ion cell (4.44Wh) for the Olympia Brio mobile phone. It replaces OEM part number DRTEL-4D-01 and fits directly into the Brio's battery bay. Dimensions are 60.00 × 43.80 × 4.50mm — verify these against your existing cell before ordering.

• Olympia Brio compatibility: The Brio uses a single-cell 3.7V nominal architecture. This cell matches the voltage rail, physical footprint, and connector orientation the phone's charge IC expects. No modification required.
• Bench tested on actual hardware: We cycled this cell through a full charge and discharge on the bench. The BMS held the charge termination voltage correctly and passed charge-current data to the phone without triggering an error state.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging for the first full discharge-charge cycle. The Brio's fuel gauge IC is calibrated to the old cell's discharge curve. One complete cycle at standard current lets it map the new cell accurately before higher charge rates are applied.

Why the Brio reports wrong battery percentage after a cell swap

The Brio uses a coulomb-counting fuel gauge IC that tracks charge in and out relative to a stored discharge curve. When you swap to a new cell, that stored curve no longer matches the new cell's actual characteristics. The phone reads state-of-charge against the wrong reference, so the percentage display drifts. One full discharge to auto-off followed by a complete charge to 100% resets the reference and brings the gauge back into alignment.

Sudden shutdown at 20–30% on the replacement cell

This happens because the new cell's internal resistance is slightly different from the depleted original. Under modem transmission or screen-on load, the voltage drops sharply below the BMS cutoff threshold even though the displayed percentage looks safe. The phone interprets this voltage cliff as a fault and shuts down. Run two full discharge-charge cycles to let the fuel gauge IC re-anchor its low-voltage endpoint — target a resting cell voltage of 3.6–3.7V at the 30% mark after calibration.