BLU Bar Q N5B80T Compatible Battery 3.7V 750mAh

BLU Bar Q — 3.7V Li-ion Replacement Battery (N5B80T)

This is a 3.7V, 750mAh Li-ion replacement battery for the BLU Bar Q mobile phone. It replaces part number N5B80T and fits the Bar Q directly. Use it when the original cell no longer holds a charge or the phone shuts down unexpectedly during calls or light use.

• BLU Bar Q fit: The Bar Q uses a compact 46.20 × 34.14 × 5.68mm cell with a low 3.7V nominal rail. The connector and BMS handshake match the original N5B80T spec, so the phone's charge IC accepts the cell without flagging an incompatible battery warning.
• Bench tested on actual hardware: We cycled this cell through a full discharge-to-charge sequence on the Bar Q platform. The BMS held charge termination at the correct cutoff voltage and did not trip into protection mode under the phone's normal load draw.
• Fuel gauge recalibration on first use: On first installation, disable fast charging if available and run one complete discharge-to-charge cycle before normal use. This lets the Bar Q's fuel gauge IC map its coulomb counter against the new cell's discharge curve — without it, percentage readings will be inaccurate from the start.

Why the BLU Bar Q reports wrong battery percentage after a cell swap

The Bar Q'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 actual cell behaviour. The IC keeps reporting against old data until it relearns. One full discharge down to auto-shutoff, followed by an uninterrupted charge to 100%, forces the coulomb counter to reset against the new cell's actual capacity.

Sudden shutdown at 20–30% on the BLU Bar Q

This is a voltage cliff failure — not a capacity problem. When the modem transmits or the screen refreshes at full brightness, current draw spikes sharply. A degraded or freshly installed uncalibrated cell briefly drops below the BMS undervoltage threshold, triggering an immediate shutdown even though the gauge still shows charge remaining. After the first full calibration cycle, the fuel gauge IC accounts for this voltage sag and the reported percentage at shutdown aligns more closely with actual cell state. If shutdowns persist past two full cycles, check that the battery contacts are clean and seated flat.