About this replacement
Sennheiser SDW 30 / SDW 60 Series — 3.7V Li-Polymer Replacement Battery (AHB732038T)
This 3.7V 450mAh Li-Polymer cell replaces the original AHB732038T battery in Sennheiser DECT wireless headsets. It fits the SDW 30, SDW 60, DW 30 HS, SDW 60 HS, and over 56 additional models in the SDW and DW headset range. The cell matches the original dimensions at 36.10 × 19.60 × 6.90mm, so it seats correctly in the headset housing.
- SDW and DW series compatibility: These headsets share the same cell format, connector pinout, and BMS handshake protocol across the SDW and DW lines. One battery spec covers the full range because Sennheiser standardised the power cell across that platform.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the base station. The BMS completed its handshake with the charging dock and the charge indicator progressed normally through each stage without fault flags.
- First charge on a new cell: Seat the headset in the base station and let it complete one full uninterrupted charge before taking a call. DECT headsets use the base station to log the new cell capacity — until that first cycle completes, the talk-time estimate displayed on paired software or the base may read inaccurate.
Base station not recognising the new pack after fitting
A replacement Li-Polymer cell ships at storage voltage — typically around 3.6V — not at the 3.7V nominal the BMS expects to see at the start of a charge handshake. Some SDW base stations respond to this by refusing to initiate the charge sequence or displaying a charge error. Reseating the headset once will usually clear this. If the base still shows an error, leave the headset seated for 10 minutes — the base trickle-charges the cell up past the BMS threshold before switching to normal charge mode.
Headset cuts out mid-call even with a new battery fitted
The SDW 30 drives both its audio circuit and the DECT radio transmitter from the same 3.7V cell simultaneously. During a call, that combined draw can cause brief voltage sag in a cell that has not yet been conditioned. The BMS reads the sag as an undervoltage event and trips the protection circuit, cutting the headset off. This behaviour typically resolves after three to five full charge and discharge cycles as the cell reaches its rated capacity — do not mistake it for a faulty unit after the first use.