AT&T Avail Li3715T42P3h415266 Replacement Battery 3.7V 1500mAh

AT&T Avail / N760 Roamer / Z990 — 3.7V Li-ion Replacement Battery (Li3715T42P3h415266)

This is a 3.7V, 1500mAh Li-ion cell that replaces the original battery in the AT&T Avail, N760 Roamer, and Z990 smartphones. It matches the OEM part number Li3715T42P3h415266 and sits within the same 41 × 51 × 6mm envelope as the factory cell. Voltage and capacity are matched to the original spec — no modification needed.

• Avail, N760 Roamer, and Z990 fit: All three models share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail. The BMS handshake on each platform accepts this cell without triggering a compatibility fault.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Avail platform. The BMS accepted charge immediately, held the 4.2V full-charge ceiling cleanly, and the protection circuit tripped correctly at low-voltage cutoff — no anomalies logged.
• Fuel gauge recalibration on first cycle: After fitting this cell, run one complete discharge down to auto-shutdown, then charge uninterrupted to 100% before using the phone heavily. The Avail's fuel gauge IC was calibrated against the old cell's discharge curve — one full cycle rewrites that reference map to the new cell.

Why the Avail reports wrong battery percentage after a cell swap

The Avail uses a coulomb counter IC that builds its percentage model from historical discharge data on the previous cell. When a new cell goes in, that stored curve no longer matches the actual charge profile. The phone reads voltage and maps it against the old curve — so 40% displayed might be 55% actual, or vice versa. One full discharge-to-shutdown followed by a complete charge cycle forces the IC to rebuild its reference against the new cell's actual voltage slope.

Sudden shutdown at 20–30% remaining on the replacement cell

This happens when the fuel gauge IC hasn't completed recalibration and the cell hits a voltage cliff under modem or display load. Even though the reported percentage looks safe, the cell voltage drops below the BMS cutoff threshold — typically around 3.0V under load — and the phone shuts off. It is not a faulty cell. Charge fully, let the gauge recalibrate over one complete cycle, and the shutdowns stop. If they persist beyond two full cycles, measure resting voltage — it should sit above 3.7V after a full charge.