About this replacement
Telex PB24ND-TX / PB24N — 3.7V Li-Polymer Replacement Battery (GPB 783448)
This 3.7V, 1800mAh Li-Polymer cell replaces the original GPB 783448 battery in the Telex PB24ND-TX and PB24N wireless headset transmitters. It restores power to the portable transmitter unit that carries your DECT audio signal. Dimensions are 50.94 × 34.20 × 9.90mm — the same footprint as the factory cell.
- PB24ND-TX and PB24N transmitter fit: Both models run the same 3.7V rail with an identical connector and BMS handshake. The GPB 783448 cell addresses both, so the base station recognises the pack without any manual pairing step.
- Bench tested on actual hardware: We cycled this cell under combined audio and DECT radio draw — the dual load the transmitter puts on the pack during active calls. The BMS held cutoff thresholds steady across repeated charge cycles with no unexpected trip events.
- First-use transmitter tip: Seat the transmitter in the base station and run a complete charge cycle before taking your first call. The base station uses that cycle to log the new cell's capacity — without it, the talk-time indicator reads inaccurately for the first several sessions.
Why the PB24ND-TX cuts out mid-call on a fresh battery
The PB24ND-TX transmitter draws current from two sources simultaneously — the audio codec and the DECT radio module. Under that combined load, a cell sitting at storage voltage (around 3.6V) can sag below the BMS cutoff threshold before the battery reads as depleted on the indicator. This looks like a hardware fault but it is a voltage floor issue. The fix is a full charge cycle from the base station before first use — that brings the cell to 4.2V and gives the BMS accurate headroom data. After that first cycle, mid-call dropouts from voltage sag stop.
Base station shows a charging error after fitting the new cell
A charging error on the base station display usually means the BMS handshake between the new cell and the base controller did not complete. This happens when the transmitter is removed from the base during the first few minutes of charge — the base resets the session and flags an error. Remove the transmitter, wait 10 seconds, and reseat it firmly so the contacts are flush. Leave it undisturbed until the charge indicator cycles through fully and the base confirms a completed session.