Logitech UE Boombox Replacement Battery DGYF001 3.7V 3400mAh

Logitech UE Boombox — 3.7V Li-ion Replacement Battery (DGYF001)

This 3.7V, 3400mAh Li-ion cell replaces the original battery in the Logitech UE Boombox portable Bluetooth speaker. It fits the 984-000304 model and matches the OEM part numbers DGYF001, GPRLO18SY002, and 533-000096. Swap it when the original no longer holds enough charge to sustain untethered playback.

• UE Boombox 984-000304 fit: The Boombox uses a single-cell 3.7V nominal Li-ion pack with a four-pin BMS connector. This cell matches that voltage rail and connector pinout so the speaker's charging circuit and fuel gauge read correctly after installation.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the UE Boombox platform. The BMS accepted the pack without error flags, charge termination triggered at 4.2V, and the fuel gauge tracked accurately across the full state-of-charge window.
• Monthly discharge cycle for the Boombox: Let the speaker run down below 20% at least once a month before plugging in. The Boombox is typically kept topped off on a desk between uses — constant shallow cycling without a full discharge causes the fuel gauge to drift and accelerates capacity fade on the Li-ion cell.

Bluetooth dropping at high volume on the UE Boombox

At maximum volume the amplifier and Bluetooth radio draw current simultaneously, creating sharp combined load spikes on the cell. A degraded or partially discharged battery sags under that combined draw, pulling the supply rail low enough that the radio module resets. The speaker reconnects within seconds, which is why users mistake it for a wireless interference problem. Replace the battery and keep the charge above 30% during high-volume use to stay above the sag threshold.

Audio distorting before the battery indicator reaches empty

This happens when the cell's internal resistance has risen enough that it can no longer sustain the amplifier's output voltage under load, even though the resting voltage still reads mid-range. The amplifier clips because the voltage rail drops below its minimum operating point during loud transients, not because the cell is empty. The fuel gauge reads a resting voltage — it does not see the sag under load. If distortion starts at full or half charge, measure the cell voltage under load; anything below 3.4V under drive is a sign the cell needs replacement.