About this replacement
JBL Boombox 3 — 7.4V Li-ion Replacement Battery (IDA109GA)
This 7.4V, 13500mAh (99.9Wh) Li-ion battery replaces the original IDA109GA cell pack in the JBL Boombox 3 portable Bluetooth speaker. It fits the Boombox 3 and the ICA068GA variant. When the original pack no longer holds charge or drops voltage under load, this is the direct cell replacement.
- Boombox 3 and ICA068GA compatibility: Both the Boombox 3 and ICA068GA share the same 7.4V cell architecture, connector pinout, and BMS communication protocol — the same pack services both without modification.
- Bench tested on actual hardware: We cycled this pack through charge and discharge on the Boombox 3 platform. The BMS handshake completed correctly, charge acceptance was normal from first cycle, and the cell voltage held stable under combined amplifier and Bluetooth radio draw at high output.
- Monthly discharge cycle for Boombox 3 users: Let the speaker run below 20% at least once a month before recharging. The Boombox 3 is typically left on a desk or countertop and topped off constantly — shallow cycling without a full discharge causes fuel gauge drift and accelerates capacity fade on these Li-ion cells.
Why the Boombox 3 reads full charge but audio cuts out during extended play
The Boombox 3 amplifier draws a sharp current spike at high volume, and an aged or degraded cell cannot sustain voltage under that load even when the fuel gauge shows full. The BMS reads resting cell voltage, not load voltage — so the indicator looks fine until the amplifier pulls hard and the cell sags below the cutoff threshold. A replacement cell with full capacity restores the headroom the amplifier needs. If the new pack still cuts out, check that the charge cycle completed fully before extended play.
USB-C charge port shows no activity on a deeply discharged Boombox 3
If the cell has dropped below approximately 2.5V per cell, the BMS locks out charging to protect against unsafe recovery — the speaker will not respond to USB-C power delivery at all. Connect the charger and leave it undisturbed for 15 to 20 minutes; some BMS firmware includes a trickle pre-charge routine that slowly brings the cell back above the acceptance threshold before normal charging begins. If the port still shows no activity after 30 minutes, the original cell has likely failed below recoverable voltage — that is when replacement is the correct fix. After fitting a new pack, confirm the indicator LED activates within two minutes of connecting USB-C.