iRiver U10 Replacement Battery 3.7V 720mAh KPPJFGB6

iRiver U10 / Clix Series — 3.7V Li-Polymer Replacement Battery (KPPJFGB6)

This 3.7V 720mAh Li-Polymer cell replaces part number KPPJFGB6 in the iRiver U10 portable media player. It fits the U10, U10CT, Clix 2GB, and Clix 4GB. At 40.80 × 29.23 × 3.80mm, it matches the original cell's footprint for a direct fit inside the chassis.

• U10 and Clix platform fit: The U10 and Clix 2GB/4GB share the same battery bay dimensions and connector orientation, so one cell covers the full range. The flat Li-Polymer pouch format is specific to this chassis — a cylindrical cell will not fit.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a U10 unit. The BMS handshake completed without error flags, and the device reported charge state correctly from the first cycle.
• First charge after installation: Media players like the U10 often ship or sit in storage with the cell at near-zero voltage. Connect the device to its charger immediately after installing the new cell and leave it charging for at least 30 minutes before attempting to power it on — this clears the deep discharge protection state that blocks normal startup.

Battery percentage jumping after swapping the cell in a Clix or U10

After a cell swap, the U10's fuel gauge reads a voltage curve that no longer matches its stored calibration data from the old cell. This causes the percentage indicator to jump — sometimes showing 80% one moment and 40% the next. The gauge recalibrates by learning the new cell's discharge profile over one or two full cycles. Run the battery down until the device shuts off, then charge it fully to 4.2V and repeat once more.

Playback cutting out before the battery indicator shows empty

The audio amplifier in the U10 draws a higher current spike during playback than the display or UI does at idle. At the tail end of a discharge curve, voltage sags under this load and drops below the amplifier's minimum operating threshold before the battery gauge reaches zero. The device cuts audio or shuts down, even though the voltage-threshold indicator still shows a charge remaining. A fresh cell with low internal resistance reduces this sag — if cutouts persist after installing a new cell, verify the battery contacts are clean and making full contact.