About this replacement
RCA Lyra Jukebox RD2780 — 3.7V Li-ion Replacement Battery (RD2780A-BAT)
This 3.7V Li-ion cell at 2200mAh (8.14Wh) replaces the original battery in the RCA Lyra Jukebox RD2780 MP3 player. It uses OEM part number RD2780A-BAT and fits the RD2780 directly. The cell dimensions are 66.34 × 20.43 × 18.26mm — measure your original before ordering if yours has been replaced before.
- RD2780 platform fit: The RD2780 runs a single-cell 3.7V Li-ion architecture with a BMS that monitors cutoff voltage at both ends of the discharge curve. This replacement cell uses the same voltage thresholds and connector pinout as the OEM unit, so the device's fuel gauge and protection circuit communicate without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the RD2780 platform. The BMS accepted charge current normally from the first cycle, and low-voltage protection triggered cleanly at the expected cutoff — no false trips during playback load.
- First-install charge protocol for the RD2780: After a long time in storage, the RD2780 will often enter deep-discharge protection and refuse to power on. Connect the charger and leave it for at least 30 minutes before attempting to boot — the BMS needs a slow trickle input to exit that state before it will accept a normal charge rate.
Battery percentage jumping on the RD2780 after a cell swap
The RD2780's fuel gauge is calibrated to the internal resistance profile of the original cell. A new cell has a different resistance curve, so the voltage-threshold indicator reads inaccurate percentages until it recalibrates. Run two or three full charge-to-cutoff cycles without interrupting playback. After that, the displayed percentage will track actual capacity accurately.
Playback cutting out before the battery indicator reaches empty
The RD2780's audio amplifier draws a brief current spike during louder passages. Near the end of the discharge curve, cell voltage sags under that load and can dip below the BMS cutoff threshold — shutting the device down even though the indicator still shows a charge remaining. This is a voltage-sag issue, not a capacity defect. To confirm, connect the charger immediately after shutdown; if the device powers back on within seconds, sag was the cause. Keeping volume below maximum extends the usable portion of each charge cycle on a new cell.