About this replacement
Pharos M619 / Mercury 619 / Traveler 619 — 3.7V Li-ion Replacement Battery (PZX95)
This is a 3.7V, 1400mAh Li-ion cell that fits the Pharos M619, Mercury 619, and Traveler 619 smartphones. It replaces OEM part numbers PZX95 and A83TA000F. The cell matches the original's physical footprint at 70.50 × 58.00 × 4.50mm and uses the same connector pinout.
- M619 / Mercury 619 / Traveler 619 platform fit: These models share the same battery bay dimensions, connector layout, and charge IC interface. One cell covers the full range — no adapter or modification needed.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the M619 platform. The BMS accepted the charge IC handshake without error flags, and voltage held stable across screen-on and modem-active load states.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.
Sudden shutdown at 20–30% on the replacement cell
The M619's fuel gauge IC stores a discharge curve calibrated to the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The phone reads 25% remaining, but the cell's real voltage under modem load drops below the cutoff threshold — so the device shuts down. Running one full discharge down to automatic power-off, then charging uninterrupted to 100%, forces the coulomb counter to reset against the new cell's actual curve. After that cycle, the percentage readings track correctly.
Device will not power on after sitting in storage
Li-ion cells self-discharge in storage. If the M619 has been unused for several months, the cell voltage may have dropped below 2.5V — the point where the BMS locks out to prevent damage. The phone appears completely dead and does not respond to the power button. Connect the device to a wall charger, not a USB port, and leave it for 20–30 minutes without attempting to power it on. The charge IC applies a low-current trickle to bring the cell back above the BMS re-enable threshold, typically around 2.9V, before normal charging resumes.