Swisstone BBM 320 Replacement Battery 3.7V 900mAh Li-ion

Swisstone BBM 320 / BBM 620 — 3.7V Li-ion Replacement Battery

This 3.7V 900mAh (3.33Wh) Li-ion cell replaces the original battery in the Swisstone BBM 320, BBM 320C, and BBM 620 cordless DECT handsets. It restores power to the handset so it operates away from the base station as intended. Dimensions are 53.13 × 33.96 × 4.77mm — confirm these match your existing cell before installing.

• BBM 320, 320C, and 620 compatibility: These three handsets share the same battery bay dimensions, connector orientation, and 3.7V Li-ion voltage rail. One cell fits all three without modification.
• Bench tested on actual hardware: We cycled this battery through charge and discharge on the BBM platform and confirmed the BMS holds the 3.7V nominal rail correctly. Charge termination triggers at the expected cutoff without overcharge events.
• First charge after installation: Place the handset in the base immediately after fitting this battery and leave it for a full uninterrupted charge cycle before making calls. Li-ion cells in DECT handsets that ship partially discharged need a complete baseline charge to calibrate the handset's battery indicator accurately.

Talk time shorter than expected after fitting the new battery

A new Li-ion cell can show reduced capacity on the first few cycles because the handset's fuel gauge has not yet calibrated to the new cell's charge curve. The BBM 320's battery indicator reads from a stored profile, and that profile can misread a fresh cell. Run two or three full charge-to-use cycles — charge fully in the base, use the handset until the low-battery alert triggers, then recharge completely. By the third cycle the indicator and actual capacity align.

Handset not pairing with base after battery replacement

Removing the battery from a DECT handset clears volatile memory on some models, which drops the pairing registration stored on the handset side. The base station retains its registration table, but the handset no longer matches it. Re-pair by holding the page or find button on the base for five seconds until the base LED flashes, then follow the pairing menu on the handset. Once paired, place the handset back in the base and allow a full charge before use.