UBiQUiO 401 Replacement Battery 3.7V 1700mAh Li-ion UBI-4-1300

UBiQUiO 401 — 3.7V Li-ion Replacement Battery (UBI-4-1300)

This 3.7V Li-ion battery replaces the original UBI-4-1300 cell in the UBiQUiO 401 smartphone. Capacity is 1700mAh (6.29Wh), matching the OEM specification. It restores normal device function when the original cell has degraded or lost the ability to hold a charge.

• UBiQUiO 401 fitment: The 401 uses a fixed-connector cell at 3.7V nominal. This replacement matches that voltage rail and connector pinout so the phone's charge IC and BMS communicate without fault codes or refused charge cycles.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge runs on the bench. The BMS accepted charge correctly, protection circuits triggered at the expected low-voltage cutoff, and the charge IC showed no handshake errors during the session.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC build an accurate discharge curve against the new cell before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the UBiQUiO 401 after a cell swap

The 401's fuel gauge IC stores a learned discharge curve from the old cell. When you install a new cell, that stored curve no longer matches real-world voltage behaviour. Under modem or screen load, the phone's voltage drops faster than the IC expects, and the device shuts down before the percentage reaches zero. This is not a fault with the replacement cell — it is a calibration gap. Run one full discharge from 100% down to automatic shutdown, then charge uninterrupted to 100%. After that cycle the IC recalibrates and reported percentage tracks actual cell voltage correctly.

UBiQUiO 401 won't power on after sitting in storage

Li-ion cells self-discharge in storage. If the cell drops below approximately 2.5V per cell, the BMS enters a lockout state and blocks normal charging to prevent damage. The phone shows no response when connected to a charger. Connect the device to a low-current USB source — a laptop port or a 5W charger — and leave it connected for 15 to 20 minutes without pressing the power button. This allows a trickle pre-charge to bring the cell above the BMS re-enable threshold, typically around 3.0V, after which normal charging resumes.