LG Music Flow P7 Replacement Battery 7.4V 3400mAh

LG Music Flow P7 / NP7550 / PJ9 — 7.4V Li-ion Replacement Battery (TD-Bb11LG)

This is a 7.4V, 3400mAh Li-ion battery for the LG Music Flow P7 portable wireless speaker and related models including the NP7550 and PJ9. It replaces OEM part numbers TD-Bb11LG, EAC63320601, and EAC63918901. The battery restores untethered audio playback and Bluetooth connectivity after the original cell degrades from repeated charge cycles.

• Music Flow P7, NP7550, PJ9, and PJS9W compatibility: These models share the same 7.4V dual-cell Li-ion pack, connector pinout, and BMS handshake protocol. The charge controller in each unit expects the same cell voltage window, so one battery specification covers the entire group.
• Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on the Music Flow P7 platform. The BMS negotiated correctly, cell balance remained within spec across cycles, and the speaker's charge indicator tracked accurately from empty to full.
• Monthly discharge discipline for daily-use speakers: If the P7 sits on a desk and gets topped off before it drops below 50%, the fuel gauge drifts within a few months. Run the speaker down below 20% at least once a month before recharging to keep the gauge calibrated and slow capacity fade on the Li-ion cells.

Audio distorting before the battery indicator reaches empty on the P7

The Music Flow P7's amplifier draws a sharp current spike at higher volume levels. When the cell voltage sags under that load, the amplifier clips before the battery indicator registers low. The indicator reads the resting cell voltage, not the voltage under load — so the gauge looks fine while the audio already sounds wrong. If distortion appears with 30–40% charge showing, the cell's internal resistance has risen enough that load voltage is dropping below the amplifier's clean-power threshold, typically around 6.8V under draw.

Speaker won't wake from USB charge after sitting unused for several weeks

Li-ion cells left uncharged for extended periods can drop below the minimum acceptance voltage for the P7's USB charge circuit — typically under 2.5V per cell. At that level, the BMS blocks the charge path as a protection measure and the speaker appears completely dead. Connect the charger and leave it undisturbed for 20–30 minutes without expecting any indicator response. The BMS in this pack includes a recovery trickle path that slowly raises cell voltage until the main charge cycle can engage, usually resuming normal charging once per-cell voltage climbs back above 3.0V.