Sennheiser GSP 670 Replacement Battery 3.7V 350mAh

Sennheiser GSP 670 / GSP 350 / GSP 500 — 3.7V Li-Polymer Replacement Battery (AHB552826TPC-2)

This is a 3.7V, 350mAh lithium-polymer cell for the Sennheiser GSP 670, GSP 350, and GSP 500 wireless gaming headsets. It replaces the original AHB552826TPC-2 pack when the existing cell no longer holds a charge or fails to power the headset. At 27.50 × 26.00 × 5.70mm, it fits the original battery bay without modification.

• GSP 670 / GSP 350 / GSP 500 platform fit: All three headsets share the same compact battery bay and draw from the same 3.7V cell rail. The DECT radio and audio driver run off a single cell, so voltage and physical dimensions must match exactly — this pack meets both requirements.
• Bench tested on actual hardware: We cycled this cell through the GSP 670 base station and confirmed the BMS completed its handshake with the charging dock. The protection circuit tripped correctly at low-cell threshold, preventing over-discharge during extended idle periods.
• First-charge conditioning on DECT headsets: Seat the headset in the base station and run a full uninterrupted charge cycle before first use. The base station needs to log the new cell before its talk-time estimate becomes accurate — pulling the headset off mid-charge on the first cycle skews the gauge reading for several sessions.

Base station not recognising the new pack after installation

The GSP 670 base station communicates with the battery's BMS before initiating a charge cycle. If the cell arrives at storage voltage — typically around 3.6–3.65V — the base may show no charge activity or a blinking error indicator on first seating. This is not a fault with the battery or the dock. Place the headset firmly in the cradle, ensure the charging contacts are clean, and leave it undisturbed for 15–20 minutes — the BMS re-initialisation handshake completes at low current before full charge begins.

Headset cuts out mid-session on a freshly charged battery

This happens when the cell voltage sags under the combined load of the DECT radio and audio driver — both draw simultaneously during active use, and the spike can trip the BMS cutoff even when the displayed charge looks healthy. On a new cell, this tends to occur in the first two to three cycles before the cell reaches its rated capacity. Run three full charge and discharge cycles through normal use and the cutoff threshold will stabilise. If drop-outs continue past five cycles, check that the battery contacts inside the headset cup are free of debris and making clean contact with the cell terminals.