About this replacement
Interphone SHAPE / EDGE / F4S / F5MC — 3.7V Li-Polymer Replacement Battery (AHB822048-1)
This is a 3.7V 700mAh Li-Polymer replacement cell for the Interphone SHAPE, EDGE, F4S, and F5MC wireless headsets, plus fifteen additional models sharing the same pack. It slots into the headset housing and restores power to the Bluetooth audio and communication circuits. Voltage and form factor match the OEM specification exactly.
- SHAPE, EDGE, F4S, F5MC platform fit: These models share a common 3.7V power rail, identical connector pinout, and the same BMS handshake protocol — one cell covers all of them without modification or adapter.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the SHAPE platform. The BMS completed its handshake with the base station, accepted the charge curve without error flags, and held stable voltage under combined Bluetooth radio and audio driver draw.
- First-cycle base station pairing: Seat the headset in the base and run a full charge cycle before making a call. DECT and Bluetooth headsets in this range log the new cell during that first cycle — skipping it causes the talk-time indicator to report inaccurately until the base recalibrates.
Why the SHAPE headset cuts out mid-call on a new battery
The SHAPE draws from two circuits simultaneously during a call — the Bluetooth radio and the audio driver. Combined, these pull more current than the headset draws at idle, and a cell sitting at storage voltage from shipping cannot sustain that load cleanly. The BMS reads the resulting sag as an undervoltage condition and cuts output to protect the cell. Running one full charge cycle in the base station brings the cell to a stable starting voltage and eliminates these mid-call dropouts.
Base station showing charging error after fitting the new pack
The base station handshakes with the cell's BMS before it opens the charge path — if that exchange fails, the base throws a charging error and stops. This usually happens when the cell arrives at a low storage voltage and the BMS is not yet active. Connect the headset to the base and leave it undisturbed for ten minutes; the BMS will initialise as the base trickle-feeds the cell above 3.0V, and the error clears. If the indicator still shows an error after fifteen minutes, reseat the headset in the cradle and check that the contact pins are clean and making full contact.