Sirius GEX-XMP3 Replacement Battery 3.7V 800mAh

Sirius GEX-XMP3 / XMP3i — 3.7V Li-ion Replacement Battery (XM-6900-0004-00)

This 3.7V 800mAh Li-ion cell replaces the original battery in the Sirius GEX-XMP3, XMP3i, and XMP3H1 portable satellite radio receivers. It matches the OEM dimensions at 55.46 × 35.66 × 4.88mm and uses the same connector and BMS handshake as the factory unit. Capacity is rated at 2.96Wh — identical to the original specification.

• GEX-XMP3 / XMP3i / XMP3H1 fit: All three models share the same battery bay dimensions, connector pinout, and voltage rail. The BMS on each unit expects the same 3.7V nominal cell — no firmware or hardware differences affect battery compatibility across this group.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the GEX-XMP3 platform and confirmed the BMS accepts the cell without fault codes. The protection circuit tripped correctly at the low-voltage cutoff, and charge acceptance was normal from a cold start.
• Post-install charge requirement: After fitting this battery, connect the device to its charger before powering on. Cells shipped in storage-safe partial charge may sit below the GEX-XMP3's wake threshold — the unit will appear dead until the charger delivers enough trickle current to bring the cell above the BMS enable voltage.

Battery percentage jumping after cell swap on the GEX-XMP3

The GEX-XMP3 uses a voltage-threshold fuel gauge rather than a coulomb counter. After a cell swap, the device has no learned discharge curve for the new cell, so the percentage display recalibrates in steps rather than smoothly. This is normal behaviour and not a fault with the replacement cell. Run two or three full charge-to-cutoff cycles and the displayed percentage will track more accurately against actual remaining capacity.

Playback cutting out before the battery indicator shows empty

The audio amplifier in the GEX-XMP3 draws a higher instantaneous current than the display or tuner circuits. As the cell discharges toward its lower voltage limit, internal resistance rises and the amplifier can no longer pull sufficient current — the device cuts audio or shuts off even though the fuel gauge still shows a charge remaining. This is a voltage-sag effect at end-of-discharge, not a capacity fault. If this happens, connect the charger immediately; a short charge session will recover enough cell voltage to resume playback.