About this replacement
Jabra Evolve 75 — 3.7V Li-Polymer Replacement Battery (AHB572535PST)
This is a 3.7V, 400mAh Li-Polymer battery for the Jabra Evolve 75 wireless headset. It replaces part number AHB572535PST — the original cell inside the Evolve 75 earcup. When your headset drops off calls early or won't hold a charge, this is the cell that needs replacing.
- Evolve 75 compatibility: The Evolve 75 runs a single Li-Polymer cell at 3.7V nominal. The AHB572535PST spec — 36.60 x 25.50 x 5.50mm — matches the internal cavity exactly. The BMS on the Evolve 75 negotiates charge termination with the base station, so cell voltage and capacity must sit within the original spec range for the base to accept the pack.
- Bench tested on actual hardware: We ran this cell through charge cycles on the Evolve 75 base station and confirmed the BMS completed handshake without error. Charge termination triggered correctly at full cell voltage. No overcurrent flags or charging faults were recorded during testing.
- First cycle in the base station: Dock the headset in the base and leave it for a complete charge cycle before taking a call. The Evolve 75 base station logs the new cell during that first cycle — until it does, the talk-time estimate displayed on paired devices will be inaccurate or absent.
Base station showing full charge but headset cuts off after short use
A replacement cell ships at storage voltage — typically between 3.6V and 3.85V — not at full charge. The Evolve 75 base station can read this as "charged" before the cell has completed a proper first cycle. The headset then runs down fast because the BMS hasn't established accurate state-of-charge tracking. One full uninterrupted charge cycle in the base resolves this — the cell needs to reach 4.2V and terminate normally before the BMS calibrates correctly.
Evolve 75 cutting out mid-call on a replacement battery
The Evolve 75 draws from the battery for both audio processing and the DECT radio simultaneously. Under that combined load, a weakened or poorly seated cell can sag below the BMS cutoff threshold — the headset shuts off even though the indicator showed charge remaining. This is a voltage sag failure, not a capacity failure. Check the cell is fully seated with no connector play, complete a full charge cycle, and confirm resting voltage reads above 3.7V before the next call.