About this replacement
HME MB Base Stations / WS200 / Pro 850 — 7.2V Ni-MH 2000mAh Replacement Battery (BAT850)
This is a 7.2V, 2000mAh Ni-MH replacement battery for HME wireless headset base stations. It fits the MB Base Stations, MB100 Base Station, WS200, and Pro 850 Intercom systems. When the original cell degrades, the base station loses its ability to hold charge and communicate with headsets — this battery restores that function.
- MB Base Station and Pro 850 compatibility: These units share the same 7.2V Ni-MH cell format, connector pinout, and BMS handshake protocol. A single replacement cell services both platforms without modification.
- Bench tested on actual hardware: We ran this pack through charge acceptance and communication handshake on an MB Base Station. The BMS completed recognition without errors and the pack reached full charge voltage cleanly across cycles.
- First-cycle base station logging: Seat the new battery and charge the headset in the base station for one complete cycle before use. DECT base stations log the new cell during that first full charge — until logging completes, the talk-time estimate displayed may read inaccurately low.
Why the Pro 850 base station shows a charging error after a battery swap
The Pro 850 base station uses a BMS handshake to verify the pack before enabling the charging circuit. A fresh replacement cell often arrives at storage voltage — around 6.0V — which sits below the threshold the base station expects to see when initiating that handshake. The base then flags a charging error rather than proceeding. Connecting the pack and leaving it seated for 10–15 minutes allows the base to trickle-charge the cell to a voltage where the handshake can complete normally.
Headset cuts out mid-call after a new battery fits and base shows full charge
This happens when the replacement cell was never taken through a proper first full cycle — the base logs a partial state of charge as 100% and the headset depletes faster than expected. It is not a fault with the battery cell itself. Place the headset in the base with the new pack installed and allow a full uninterrupted charge before making calls. After two to three complete charge-discharge cycles, the base station recalibrates and the headset sustains a full talk session at the rated 2000mAh capacity.