USCellular Director N850L Replacement Battery 3.7V 1500mAh

USCellular Director / N850L — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1500mAh Li-ion cell built to replace the original battery in the USCellular Director (model N850L). It fits directly into this smartphone and restores power to calls, messaging, and core functions. Capacity is rated at 5.55Wh, matching the stock cell specification.

• Director / N850L platform fit: Both model names refer to the same hardware platform. The connector pinout, physical footprint (41 × 51 × 6mm), and BMS handshake voltage all align to the same battery slot — no adapter or modification needed.
• Bench tested on actual hardware: We cycled this cell through charge and full discharge on the Director platform. The BMS accepted the charge profile without interruption, and protection circuits tripped correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: After installation, disable fast charging if your Director supports it, then run one complete discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before the OS starts reading percentage data from it.

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

This happens because the fuel gauge IC is still calibrated to the old cell's discharge curve. When the new cell hits a voltage point the IC doesn't expect — typically around 3.6–3.7V under load — the OS sees a cliff and shuts down rather than risk going below the safe floor. It is not a fault with the replacement cell. One full discharge cycle from 100% down to automatic shutoff, followed by a full charge, resets the coulomb counter reference. After that cycle, percentage reporting stabilises.

Director not powering on after the battery sat discharged in storage

Li-ion cells that drop below roughly 2.5V trigger a BMS lockout to prevent damage from deep discharge. A phone that shows no response — no boot screen, no charging indicator — when connected to power is likely in this state. Connect the device to a wall charger (not a PC USB port, which may not supply enough current) and leave it for 20–30 minutes without pressing the power button. Once the cell recovers above the BMS re-enable threshold, the charging indicator will appear and normal startup resumes.