E-TEN glofiish X500 Replacement Battery 3.7V 3000mAh 49004440

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

This 3.7V 3000mAh Li-Polymer battery replaces the original cell in the E-TEN glofiish X500 and X500+. Both devices share the same battery bay dimensions and connector, so one part covers both models. Capacity is 3000mAh (11.1Wh) — drawn from product data, not estimated.

• X500 and X500+ shared battery bay: Both models use the same 65.98 × 45.39 × 10.40mm cell footprint and the same two-pin connector orientation. The BMS handshake logic is identical across both revisions, so the replacement integrates without hardware modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the glofiish X500 platform. The BMS held charge acceptance cleanly, the protection circuit tripped correctly at low-voltage cutoff, and the fuel gauge IC tracked state-of-charge without erratic jumps after the first full cycle.
• First-cycle fuel gauge reset: On first use after installation, run one complete discharge to auto-shutoff followed by a full uninterrupted charge. The glofiish fuel gauge IC calibrates its coulomb counter against the new cell's discharge curve during this cycle — skipping it leaves the percentage readout misaligned by as much as 15–20%.

Sudden shutdown at 20–30% on the glofiish X500

The X500's Windows Mobile platform draws a hard spike when the GSM modem transmits or the display backlight hits full brightness. An aged or deeply discharged cell can no longer sustain voltage under that load — it sags below the BMS cutoff threshold even while the fuel gauge still reads 20–30%. This is a voltage-cliff failure, not a capacity failure. The fix is a full recalibration cycle: discharge the new cell to auto-shutoff, then charge uninterrupted to 100%, which anchors the fuel gauge IC to the actual discharge curve of the new cell.

Device won't power on after the battery sat in storage

Li-Polymer cells self-discharge in storage. If the glofiish X500 or the replacement cell was stored without use for several months, the cell voltage can drop below 2.5V per cell — the point at which the BMS locks out to prevent damage. The device will show no response at all: no boot screen, no charge indicator. Connect the original E-TEN charger and leave it for 20–30 minutes without pressing the power button; most BMS circuits on this platform include a trickle-recovery mode that brings the cell back above 3.0V before allowing normal charge current. Once the charge LED activates, the BMS has re-initialised and normal charging resumes.