Poly SY20 USB-A Replacement Battery 3.7V 2600mAh A0697

Poly SY20 USB-A — 3.7V Li-ion Replacement Battery (A0697)

This is a 3.7V, 2600mAh (9.62Wh) Li-ion replacement battery for the Poly SY20 USB-A portable speaker. It fits directly where the original A0697 cell sits. When the stock battery no longer holds a charge or the speaker dies mid-session, this cell restores full cordless operation.

• SY20 USB-A platform fit: The SY20 USB-A runs a single-cell 3.7V Li-ion architecture. The A0697 matches the cell voltage, physical dimensions (66.00 × 21.70 × 20.00mm), and connector orientation the onboard charging circuit expects. No modifications needed.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the SY20 USB-A platform. The BMS accepted the cell without error, topped off cleanly to 4.2V, and the protection circuit triggered correctly at the low-voltage cutoff threshold.
• Monthly full-cycle discipline for the SY20: The SY20 spends most of its life on a desk, constantly topped off. Discharge the cell below 20% at least once a month before recharging. Constant top-off charging without a full discharge causes fuel gauge drift and accelerates capacity fade on this Li-ion cell.

Audio distorting before the battery indicator reaches empty on the SY20

As the cell discharges toward its lower end, voltage sag under amplifier load can pull the rail below the amp's clean operating range before the fuel gauge triggers a low-battery warning. The amplifier clips under that sag, producing audible distortion even though the indicator still shows charge remaining. A degraded or aged cell sags harder and faster than a fresh one — the distortion onset moves earlier in the discharge curve. Replacing the cell with a fresh A0697 raises the resting voltage and reduces sag, pushing distortion onset back toward actual empty.

Bluetooth dropping at high volume on the SY20 USB-A

Loud audio on the SY20 drives simultaneous current draw from both the amplifier and the Bluetooth radio. That combined spike can pull cell voltage below the radio module's minimum operating threshold for a fraction of a second, causing the Bluetooth stack to reset and the connection to drop. This happens more often on cells that have lost capacity through shallow cycling, since their internal resistance is higher and voltage sag under peak draw is steeper. If drops occur only at higher volume levels and not at low volume, the cell — not the radio — is the likely cause.