Sennheiser SDW 10 Compatible Battery 3.7V 360mAh Li-Polymer

Sennheiser SDW 10 Series — 3.7V Li-Polymer Replacement Battery (AHB552826TPC)

This is a 3.7V, 360mAh lithium-polymer cell for the Sennheiser SDW 10 wireless DECT headset and related SDW series models. It fits the SDW 10, SDW 10 HS, SDW 5013, SDW 5014, and additional SDW variants sharing the same battery bay and connector. Swap it in when the original cell no longer holds enough charge to complete a full work session.

• SDW series compatibility: These models share a common battery cavity, connector pinout, and BMS handshake protocol across the SDW 10 and SDW 5000 sub-series. The same 3.7V cell architecture runs both the DECT radio module and audio amplifier stage, so the pack is interchangeable across the listed variants without firmware conflict.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on an SDW base station and monitored the BMS handshake. The protection circuit responded correctly to charge termination and low-voltage cutoff, and the base station registered the new cell without error flags.
• First-charge protocol for DECT headsets: Dock the headset in the base station and leave it undisturbed for a complete charge cycle before taking a call. The base needs to complete a full BMS log of the new cell before its talk-time estimate becomes accurate — pulling it early skips that calibration step.

Base station not recognising new pack after installation

The SDW base uses a BMS handshake to confirm a valid cell before it begins charging. A new pack shipped at storage voltage — typically around 3.6V — can sit just below the threshold the base expects for an active cell. If the LED flashes an error or charging does not begin, remove the headset, wait 10 seconds, and re-dock it. In most cases the second dock attempt initiates the handshake correctly and charging starts within 30 seconds.

Headset cuts out mid-call even with a recently charged battery

The SDW headset draws from the cell simultaneously for the DECT radio transmitter and the audio amplifier. That combined draw creates brief current spikes that can trip the BMS low-voltage cutoff if the cell voltage sags under load — even when the headset shows adequate charge at rest. This happens most on the first two or three cycles, before the cell reaches its rated capacity. Run three full charge-and-use cycles and the voltage sag on load decreases as the cell conditions.