BQ BQS-5050 Replacement Battery 3.8V 2300mAh Li-ion

BQ BQS-5050 — 3.8V Li-ion Replacement Battery (BQS-5050)

This is a 3.8V, 2300mAh Li-ion replacement battery for the BQ BQS-5050 smartphone. It slots into the original battery bay and connects to the device's charge IC and fuel gauge circuit. Capacity matches the factory specification at 8.74Wh.

• BQS-5050 platform fit: The BQS-5050 uses a single-cell 3.8V nominal rail with a proprietary connector keyed to the mainboard's PMIC. Voltage and connector geometry must match exactly — this cell does both.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the BQS-5050 mainboard. The BMS accepted charge current without cutoff events, and the fuel gauge IC tracked state-of-charge across the full discharge curve without erratic jumps.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the BQS-5050 after a cell swap

This is a voltage cliff issue, not a capacity fault. When the modem transmits or the screen peaks, the draw spikes sharply. A new cell with an uncalibrated fuel gauge IC allows the reported percentage to sit at 20–30% while the actual open-circuit voltage has already dropped below the PMIC's cutoff threshold. The phone interprets this as a hard undervoltage event and shuts down to protect the board. One full discharge-charge cycle syncs the coulomb counter to the real cell curve and eliminates most of these events.

BQS-5050 not powering on after the battery sat in storage

Li-ion cells self-discharge in storage. If the cell voltage drops below approximately 2.5V per cell, the BMS trips a deep-discharge lockout and the phone will not respond to a normal power-on press. Connect the phone to a wall charger — not a PC USB port — and leave it for 15–20 minutes without pressing anything. The charge IC trickle-charges the cell back above the BMS re-enable threshold, typically around 2.9V, at which point the BMS releases and normal charging resumes.