Li3817T42P3h735044 Replacement Battery MetroPCS N9120 3.7V

MetroPCS N9120 / Avid 4G — 3.7V Li-ion Replacement Battery (Li3817T42P3h735044)

This is a 3.7V, 3600mAh Li-ion replacement battery for the MetroPCS N9120, Avid 4G, and Avid smartphones. It carries OEM part number Li3817T42P3h735044 and fits the ZTE-manufactured hardware under the MetroPCS label. Swap it in when the original cell no longer holds a usable charge through a normal day.

• N9120 / Avid 4G platform fit: These three model names share the same ZTE hardware platform, the same connector pinout, and the same BMS handshake protocol. One cell covers all three — no adapter or modification required.
• Bench tested on actual hardware: We ran this cell through a full charge and load cycle on the N9120 board. The BMS accepted the charge profile without fault, voltage held steady at 3.7V nominal under screen-on and modem-active load, and the protection circuit triggered cleanly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and let the phone complete one full discharge-to-charge cycle at standard current. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging begins pushing current into an uncalibrated state.

Sudden shutdown at 20–30% on the N9120 after cell swap

The N9120's fuel gauge IC retains the discharge curve from the old, degraded cell. When a new high-capacity cell is installed, the IC's stored curve no longer matches actual cell voltage under load. The modem radio draws a surge of current, cell voltage dips sharply, and the IC interprets that dip as a depleted cell — triggering a shutdown even though charge remains. One complete discharge cycle without fast charging lets the coulomb counter reset and re-anchor to the new cell's actual voltage floor, typically around 3.4V under load.

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

Li-ion cells self-discharge in storage. If this cell dropped below approximately 2.5V per cell during a long storage period, the BMS trips into lockout mode to prevent damage. The phone will show no response — no charge indicator, no boot. Connect the phone to a wall charger rated at least 5V/1A and leave it untouched for 20–30 minutes. Once the BMS detects voltage recovering above its wake threshold, the charge IC takes over and the phone should display the charging indicator.