ZTE U288G 3.7V 1700mAh Replacement Battery Li-ion

ZTE U288G — 3.7V Li-ion Replacement Battery (U288G)

This is a 3.7V 1700mAh Li-ion battery for the ZTE U288G smartphone. It replaces a degraded original cell that no longer holds enough charge for calls, messaging, and daily app use. Capacity is rated at 6.29Wh and matches the original voltage rail exactly.

• U288G platform fit: The U288G uses a single-cell 3.7V Li-ion configuration with a fixed connector orientation and BMS handshake tied to that voltage rail. A cell outside that spec trips the charge IC and prevents a full charge cycle from completing.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the U288G platform. The BMS accepted the cell without fault codes, and the charge IC completed a full constant-current to constant-voltage charge sequence without cutoff errors.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.

Why the U288G reports wrong battery percentage after a cell swap

The U288G uses a fuel gauge IC that builds its state-of-charge model against the discharge curve of the original cell. When you install a new cell, that stored curve no longer matches reality. The gauge will report percentages based on old data until it runs at least one full cycle. Run the phone from 100% down to automatic shutdown, then charge uninterrupted to 100% — after that cycle the gauge recalibrates against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC is still using a calibration map from a worn cell. The old cell's voltage floor sat higher than a fresh cell's, so the gauge reads 20–30% when the new cell is actually near depletion under modem or screen load. The voltage sags below the BMS cutoff threshold before the gauge reaches zero. One full discharge-to-shutdown and uninterrupted recharge to 100% resets the coulomb counter and stops premature shutoffs.