AT&T SMT5700 Replacement Battery 3.7V 2200mAh BTE5700

AT&T SMT5700 — 3.7V Li-ion Replacement Battery (BTE5700)

This is a 3.7V lithium-ion cell rated at 2200mAh (8.14Wh), built to the BTE5700 spec for the AT&T SMT5700 smartphone. It slots directly into the SMT5700 battery bay and connects to the same three-contact interface as the original. Voltage and physical dimensions match the OEM unit at 51.13 × 38.39 × 10.23mm.

• SMT5700 compatibility: The SMT5700 and SMT-5700 share the same battery bay geometry and charge controller. This cell uses the same 3.7V nominal rail and contact pitch, so the phone's charge IC communicates with the BMS without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the SMT5700 platform. The BMS handshake completed on the first cycle, the charge IC accepted the cell without fault flags, and cutoff voltages held within spec at both the high and low ends.
• Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one full discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before the coulomb counter starts reporting percentage to the OS.

Sudden shutdown at 20–30% on the SMT5700 after a cell swap

The SMT5700's fuel gauge IC retains the discharge curve from the old cell in its memory after a swap. When the new cell's actual voltage profile diverges from that stored curve, the OS reads 20–30% remaining while the cell is already near its real floor. Under modem or screen load, voltage drops sharply, the BMS hits its lower cutoff, and the phone shuts off without warning. One full uninterrupted discharge to auto-shutdown, followed by a complete charge, forces the coulomb counter to relearn the new cell's curve. After that cycle, the percentage readout tracks correctly under load.

SMT5700 not powering on after the replacement battery sat in storage

Li-ion cells self-discharge in storage, and if voltage drops below approximately 2.5V per cell, the BMS enters a lockout state to prevent damage. In lockout, the phone shows no charge indicator and will not respond to the power button. Connect the phone to a wall charger — not a PC USB port — and leave it undisturbed for 15–20 minutes. The charge IC trickle-charges the cell back above the BMS re-enable threshold, after which normal charging resumes. If the charge indicator still does not appear after 30 minutes on a wall adapter, check that the charger output meets the SMT5700's minimum 5V/500mA requirement.