About this replacement
Jabra Engage 75 Convertible — 3.7V Li-Polymer Replacement Battery (AHB472625PLT)
This 3.7V, 250mAh Li-Polymer cell replaces the internal battery in the Jabra Engage 75 Convertible wireless DECT headset. It also fits the Engage 75, Evolve 65, and Evolve 80 — all platforms sharing the same cell footprint, voltage rail, and connector. Capacity is 250mAh (0.93Wh), taken from the product specification, not estimated.
- Engage and Evolve platform fit: These headsets share a common internal form factor — same 28.10 x 24.45 x 4.76mm cell envelope, same 3.7V nominal rail, and the same BMS handshake protocol the base station uses to log charge state. Swapping to this cell does not require firmware changes or re-pairing.
- Bench tested on actual hardware: We cycled this cell through the Engage 75 Convertible base station and monitored BMS communication at each stage. The protection circuit responded correctly to charge termination and low-voltage cutoff without triggering false errors on the base unit.
- First-cycle base station logging: Seat the headset in the base station immediately after fitting the new cell and leave it for a complete charge cycle before making a call. The base's DECT firmware uses that first cycle to register the new cell's charge curve — without it, the talk-time estimate displayed on paired softphones or base LEDs will be inaccurate.
Base station showing full charge but headset cuts off after a few minutes
A freshly installed Li-Polymer cell ships at storage voltage — typically 3.6–3.7V, not full charge. The base station LED may read full because the voltage sits within a threshold the charger accepts as topped up. Under combined DECT radio and audio draw, a cell at storage voltage sags quickly and hits the low-voltage cutoff. Run one complete charge cycle in the base before use, and the cell will reach its true 4.2V charge ceiling.
Headset cutting out mid-call on a new battery
Mid-call dropout on a new cell is almost always a BMS trip caused by voltage sag under simultaneous audio decoding and DECT radio transmission. The Engage 75 Convertible draws a short current spike each time the DECT radio bursts — a new cell that has not completed its first conditioning cycle has higher internal resistance, which amplifies that sag. The BMS reads the dip as an unsafe discharge event and cuts the circuit. Three to five full charge-discharge cycles bring internal resistance down and the dropouts stop.