E-TEN glofiish X500 Replacement Battery 3.7V 2400mAh 49004440

E-TEN glofiish X500 / X500+ — 3.7V Li-Polymer Replacement Battery (49004440_X500)

This 3.7V, 2400mAh Li-Polymer cell replaces the original battery in the E-TEN glofiish X500 and X500+. Both devices share the same battery bay geometry, connector pinout, and charge IC protocol. Capacity is rated at 8.88Wh and sourced to match the original cell specification.

• X500 and X500+ compatibility: Both variants use the same voltage rail, physical footprint, and BMS handshake. The charge IC on the glofiish platform communicates with the cell through a shared three-pin connector — this replacement carries the same configuration, so the device accepts it without firmware conflict.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on a Windows Mobile platform matching the X500 charge profile. The BMS held cutoff at the correct upper voltage and did not trigger premature termination under simulated modem and display load.
• Fuel gauge recalibration on first install: After fitting this cell, run one complete discharge down to auto-shutdown, then charge uninterrupted to 100% before normal use. The glofiish fuel gauge IC reads a coulomb counter calibrated to the old cell's discharge curve — one full cycle resets that baseline against the new cell.

Sudden shutdown at 20–30% on the glofiish X500 after cell replacement

The glofiish X500 runs a combined GSM modem and display load that draws current in sharp spikes. A new Li-Polymer cell has slightly higher internal impedance on early cycles, which causes a momentary voltage sag under that load. When terminal voltage dips below the BMS cutoff threshold — typically around 3.0V — the device shuts down even though the reported state of charge is still 20–30%. This is not a defective cell. After three to five full charge cycles, impedance drops and the voltage cliff disappears.

glofiish X500 stuck on boot loop or won't power on after extended storage

Li-Polymer cells left discharged for months can drop below 2.5V per cell — at that point the BMS latches into a lockout state and blocks normal charging to prevent thermal runaway on a deeply depleted cell. The device will not power on and may not respond to the charger at all. Connect the original E-TEN charger and leave it for 20–30 minutes without pressing the power button — the charge IC will trickle current into the cell at a reduced rate until voltage climbs back above the BMS recovery threshold, approximately 2.9V, after which normal charging resumes.