BLU Studio 5.5 Replacement Battery C746440225T 3.7V 1900mAh

BLU Studio 5.5 / D610 Series — 3.7V Li-ion Replacement Battery (C746440225T)

This is a 3.7V, 1900mAh Li-ion cell for the BLU Studio 5.5 smartphone, covering models D610, D610A, and D610i. It replaces the original C746440225T battery when the cell no longer holds a useful charge. Dimensions are 73.80 × 64.10 × 4.40mm — measure your original before installing if you are unsure which variant you have.

• D610 model family compatibility: The D610, D610A, and D610i share the same battery bay dimensions, connector pinout, and BMS handshake protocol. One cell fits all three without modification.
• Bench tested on actual hardware: We cycled this cell through a full discharge and charge sequence on the D610 platform. The BMS accepted the cell on first connection, and charge termination triggered correctly at 4.2V with no false-positive cutoffs during the test cycle.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging for one complete discharge-charge cycle. The fuel gauge IC was calibrated to the old cell's discharge curve. Running one slow cycle gives the coulomb counter accurate reference data before any high-current charge session.

Sudden shutdown at 20–30% on the BLU Studio 5.5

This is a voltage cliff failure, not a capacity problem. When the modem transmits or the screen peaks at full brightness, load current spikes and cell voltage drops sharply. If the cell cannot sustain voltage above the BMS cutoff threshold during that spike, the phone shuts off even though the fuel gauge still shows charge remaining. Running one full discharge-to-shutdown cycle followed by a full uninterrupted charge lets the coulomb counter remap the actual low-voltage boundary of the new cell, which typically pushes the shutdown point below 10%.

OS reporting wrong battery percentage after the cell swap

The fuel gauge IC stores a learned discharge curve from the old cell in its internal registers. After a swap, those stored values do not match the new cell's chemistry profile, so the percentage reading drifts or jumps — especially below 40% and above 85%. The fix is one complete cycle: drain the phone until it powers off automatically, then charge uninterrupted to 100% without removing the cable. After that single cycle, the coulomb counter recalibrates against the new cell and the percentage stabilises.