About this replacement
Sony SRS-X5 — 7.4V Li-ion Replacement Battery (LIS2128HNPD)
This is a 7.4V, 3400mAh (25.16Wh) Li-ion replacement battery for the Sony SRS-X5 portable Bluetooth speaker. It fits the SRS-X5 directly, using OEM part number LIS2128HNPD. Replace this cell when the original pack no longer holds a useful charge between listening sessions.
- SRS-X5 compatibility: The SRS-X5 runs a 7.4V two-cell Li-ion pack with a BMS that monitors cell voltage and temperature. This replacement matches that voltage rail and connector exactly, so the speaker's protection circuit communicates with the pack as it would with the factory cell.
- Bench tested on actual hardware: We cycled this pack through charge and discharge on the SRS-X5 platform and confirmed the BMS accepted the cell without triggering fault states. Charge termination and low-voltage cutoff both fired at expected thresholds.
- Monthly discharge cycle for the SRS-X5: The SRS-X5 spends most of its life on a desk or shelf, topped off before it drops below 50%. Let the speaker drain below 20% at least once a month before recharging — this corrects fuel gauge drift and slows capacity fade caused by constant shallow cycling on the Li-ion cell.
Audio distortion before the battery indicator reaches empty on the SRS-X5
As the Li-ion cell ages, its internal resistance rises. Under the combined current draw of the amplifier and Bluetooth radio, cell voltage sags below what the amplifier stage needs — even when the fuel gauge still shows charge remaining. The amp clips under that sag, producing audible distortion before the low-battery indicator triggers. Replacing the cell restores the low-resistance discharge curve and removes that voltage floor problem.
Bluetooth dropping out at high volume on the SRS-X5
Pushing the SRS-X5 to high volume spikes the amplifier's current draw sharply. A degraded or deeply cycled battery cannot sustain voltage under that load, and the combined amp-plus-radio draw pulls cell voltage below the BMS trip threshold. The BMS reads this as a low-voltage fault and momentarily cuts output, breaking the Bluetooth connection. Charge the replacement pack fully to 8.4V before first use and confirm the issue clears at full charge before investigating the radio antenna.