E-TEN glofiish X800 Replacement Battery 3.7V 2600mAh US454261

E-TEN glofiish X800 — 3.7V Li-Polymer Replacement Battery (US454261 A8T)

This 3.7V, 2600mAh lithium-polymer cell replaces the original battery in the E-TEN glofiish X800 Windows Mobile smartphone. It fits directly into the X800's battery bay and matches the OEM connector and contact layout. Capacity is rated at 9.62Wh.

• glofiish X800 fitment: The X800 uses a fixed voltage rail at 3.7V nominal with a specific BMS handshake tied to the OEM part numbers US454261 A8T, E4ET011K1002, BT0010T002, BT0010T003, and E3AR061K2002. This cell matches that handshake so the device recognises it on first boot without throwing a battery-incompatible warning.
• Bench tested on actual hardware: We cycled this cell through a full discharge-charge sequence on the X800 platform. The BMS accepted the cell cleanly, charge current ramped normally through CC phase, and the device passed into CV taper without interruption.
• First-cycle fuel gauge reset on the X800: After fitting the new cell, run one complete discharge down to the automatic shutoff, then charge uninterrupted to 100%. The X800's fuel gauge IC is calibrated to the old cell's discharge curve — one full cycle rewrites that reference so percentage readings stay accurate under modem and screen load.

Sudden shutdown at 20–30% on the glofiish X800

The X800 uses a coulomb-counter fuel gauge that tracks charge state against a stored discharge curve. When the original aged cell is replaced, the stored curve no longer matches the new cell's voltage-versus-capacity profile. The phone hits a voltage cliff — where cell voltage drops sharply under modem or display load — before the gauge reaches 0%, triggering an emergency shutdown. One full discharge-charge cycle overwrites the reference curve and eliminates the premature cutoff.

glofiish X800 not powering on after sitting in storage

Li-polymer cells self-discharge during storage. If the X800 sat unused for several months, the cell voltage may have dropped below 2.5V per cell — the threshold where the BMS latches into lockout to prevent damage. The device will not respond to the power button and may show no charge indicator when plugged in. Connect the X800 to a wall charger and leave it for 20–30 minutes without pressing anything; the charge IC trickle-charges the cell back above 2.8V, the BMS releases lockout, and the device resumes normal charging.