Plantronics Poly Calisto 5300 Replacement Battery 3.7V VDL952246

Plantronics Poly Calisto 5300 — 3.7V Li-Polymer Replacement Battery (VDL952246)

This 3.7V 950mAh Li-Polymer cell is a direct replacement for the Poly Calisto 5300 conference speakerphone. It restores cordless operation to the unit when the original pack no longer holds a charge. Voltage, capacity, and physical dimensions — 45.50 × 21.40 × 9.50mm — match the OEM specification.

• Calisto 5300 platform fit: The Calisto 5300 uses a compact Li-Polymer pouch cell to keep the unit thin enough for portable use. The VDL952246 shares the same connector pinout and cell geometry as the factory pack, so the BMS handshake with the speaker's charge controller completes without errors.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Calisto 5300 platform. The BMS accepted the pack without fault codes, charge terminated correctly at 4.2V, and the protection circuit tripped at the expected low-voltage cutoff under load.
• Fuel gauge reset after swap: After fitting this replacement, run the Calisto 5300 down until it shuts off, then charge it uninterrupted to 100%. This lets the speaker's fuel gauge recalibrate to the new cell's actual capacity — skipping this step causes the indicator to read inaccurately from day one.

Capacity fade on the Calisto 5300 from constant desk-top charging

Most Calisto 5300 units live on a desk and get topped off repeatedly before dropping below 50%. Li-Polymer cells degrade faster when cycled in that upper voltage band continuously. The cell spends most of its life near 4.2V, which accelerates electrolyte oxidation at the cathode. One full discharge per month — letting the speaker shut itself off — slows that degradation and extends usable cell life.

Audio distorting before the battery indicator reaches empty

This happens because the amplifier inside the Calisto 5300 draws a sharp current spike at higher volume levels. When the cell is aged or partially discharged, internal resistance causes voltage to sag under that spike below what the amp needs to run cleanly. The result is clipping — audible distortion — while the fuel gauge still shows charge remaining. Fitting a fresh cell with lower internal resistance restores the voltage headroom the amplifier needs; check that the cell rests at 3.7V open-circuit before installation.