Pioneer GEX-XMP3 Replacement Battery 3.7V 800mAh Li-ion

Pioneer GEX-XMP3 / XMP3i / XMP3H1 — 3.7V Li-ion Replacement Battery (XM-6900-0004-00)

This is a 3.7V 800mAh Li-ion battery for the Pioneer GEX-XMP3, XMP3i, and XMP3H1 portable satellite radio players. It replaces OEM part XM-6900-0004-00 (also cross-referenced as L01L40321 and TBS100551042). When the original cell degrades, audio playback drops out early or the unit refuses to power on — this battery restores normal operation.

• GEX-XMP3 / XMP3i / XMP3H1 fit: All three variants share the same battery bay dimensions, connector pinout, and 3.7V power rail. The BMS handshake is identical across the lineup, so one cell covers the full range without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the GEX-XMP3 platform. The BMS accepted the cell without fault codes, charge termination triggered correctly at 4.2V, and the protection circuit tripped at the expected low-voltage cutoff.
• Post-swap charging on the XMP3: After fitting a new cell, connect the player to its dock or USB charger before powering it on. If the old battery fully discharged before removal, the unit may sit in a protection state that blocks startup — a short trickle charge clears this before normal charge current kicks in.

Battery percentage jumping after cell swap on the XMP3

The XMP3 estimates charge level using voltage thresholds mapped to the original cell's discharge curve. A fresh cell has a slightly different resting voltage profile until it's been cycled, so the indicator can read 80% then jump to 20% without warning. This is the fuel gauge recalibrating, not a faulty battery. Run two full charge-to-discharge cycles and the indicator settles. After the second cycle, resting voltage at full charge should read around 4.15–4.20V.

Playback cutting out before the battery indicator shows empty

The XMP3's audio amplifier draws more current than the display or radio tuner alone. At the tail end of the discharge curve — typically below 3.6V — the cell can no longer sustain that peak draw without voltage sagging briefly below the amplifier's minimum rail. The device interprets this sag as a fault and cuts audio before the battery gauge hits zero. If this happens, connect the charger immediately rather than forcing a restart — the cell is near its low-voltage cutoff and needs a charge cycle, not a reset.