Yingtai T11 Replacement Battery 3.7V 900mAh Li-ion

Yingtai T11 / T15 — 3.7V Li-ion 900mAh Replacement Battery

This 3.7V, 900mAh Li-ion cell replaces the original battery in the Yingtai T11 and T15 smartphones. Both models share the same battery bay dimensions (53.00 x 34.00 x 4.30mm) and voltage rail, so one SKU covers both. Capacity figures come from the product specification — 900mAh / 3.33Wh.

• T11 and T15 shared battery platform: Both handsets run the same 3.7V single-cell architecture with identical connector orientation and board contact spacing. Swapping between models carries no BMS handshake difference — the charge IC behaves identically on both.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a calibrated rig. The BMS held cutoff correctly at the low-voltage threshold and did not trip prematurely under modem-active load spikes.
• Fuel gauge recalibration after installation: On first use, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before any high-current protocol pushes charge into an uncalibrated state — percentage accuracy improves significantly after that single cycle.

Sudden shutdown at 20–30% on the replacement cell

A fresh cell has a steeper voltage drop near the bottom of its discharge curve than the worn cell the phone's fuel gauge was calibrated against. When the modem fires a high-power transmission burst or the screen brightness spikes, the cell voltage dips below the BMS cutoff threshold — even though the percentage reading says 25%. The phone interprets this as a hard fault and shuts down. One full discharge-to-charge cycle recalibrates the coulomb counter and brings the cutoff threshold back in line with actual remaining capacity.

Phone won't power on after the battery sat in storage

Li-ion cells self-discharge in storage. If the cell drops below approximately 2.5V, the BMS enters a lockout state to prevent damage — the phone shows nothing when you press the power button. Connect the device to a low-current charger (a standard 5V USB wall adapter works) and leave it for 20–30 minutes without pressing power. The BMS needs a trickle current to recover the cell voltage above its reactivation threshold before normal charging and boot can proceed. Once the charging indicator appears on screen, the BMS has exited lockout — charge to full before first use.