About this replacement
Pharos Traveler 117 / Traveler 127 — 3.7V Li-ion Replacement Battery (PZX91)
This is a 3.7V, 1350mAh Li-ion replacement battery for the Pharos Traveler 117 and Traveler 127 GPS navigation devices. It slots into the same battery bay as OEM part numbers PZX91, A83TA040F, and 6027B0043001. If your Traveler 117 or 127 no longer holds a charge or powers off unexpectedly, this cell replaces the degraded original.
- Traveler 117 and 127 compatibility: Both models share the same battery bay dimensions, 3.7V nominal rail, and connector pinout — one cell fits both. The BMS on each unit uses the same charge termination voltage, so no firmware or hardware difference affects fitment.
- Bench tested on actual hardware: We ran this cell through a full charge and load cycle on a Traveler 117 unit. The BMS accepted the cell without error flags, charge termination hit at 4.2V as expected, and the GPS lock sequence drew current cleanly without triggering cutoff.
- Fuel gauge recalibration after swap: After installing this cell, run one complete discharge-to-charge cycle without interruption before relying on the battery percentage indicator. The onboard fuel gauge IC is calibrated to the old cell's discharge curve — one full cycle lets it recalibrate against the new cell before reporting accurately.
Why the Traveler 117 shuts down suddenly at 20–30% remaining
This is a voltage cliff failure, not a percentage calculation error. When the original cell ages, its internal resistance rises — under the load spike of GPS signal acquisition or screen-on events, the terminal voltage drops sharply below the BMS cutoff threshold even though the fuel gauge still reads 20–30%. The device cuts power to protect the cell. A new cell with lower internal resistance sustains voltage under the same load, eliminating the false shutdown. After installation, run one full discharge cycle so the fuel gauge IC can map the new cell's actual discharge curve.
Device won't power on after sitting in storage — no response to charger
GPS units stored without use for several months can drain the cell below 2.5V per cell, triggering a BMS lockout that blocks normal charging. The charger appears to do nothing — no LED, no boot screen. Connect the device to a 5V USB charger and leave it undisturbed for 20–30 minutes; the BMS recovery circuit trickle-charges the cell back above the lockout threshold before switching to standard CC/CV charge. If the device still shows no response after 40 minutes, confirm the charger output is at least 500mA — low-current sources may not supply enough to wake the recovery circuit.