Sennheiser BA90 RI100-A/RI100-J Replacement Battery 2.4V

Sennheiser RI100-A / RI100-J Series — 2.4V Ni-MH Replacement Battery (BA90)

This is a 2.4V, 60mAh Ni-MH rechargeable cell that replaces the BA90 / E90 / E180 battery pack. It fits the Sennheiser RI100-A, RI100-J, HDI92-P, H200, HDI452-P, HDI91-P1, HDI91-P2, and over a dozen additional headset models from the same family. When the original cell can no longer hold a useful charge, this pack restores the headset to normal operation.

• RI100 and HDI family compatibility: These headsets share a common 2.4V two-cell Ni-MH architecture and the same physical pack format. The connector pinout, cell voltage, and BMS signalling are identical across the RI100-A, RI100-J, and HDI-series variants — one pack covers all of them.
• Bench tested on actual hardware: We cycled this pack in a RI100-J base station and monitored charge termination. The base detected the new cell correctly, applied delta-V cutoff at full charge, and the headset paired without any error state on the cradle indicator.
• First-cycle conditioning in the base station: Place the headset in the charging cradle for a complete uninterrupted charge cycle before making any calls. DECT base stations log the new cell during this first cycle — skipping it causes the talk-time estimate displayed on the base to read inaccurately for several sessions.

Base station not recognising the new pack after fitting

The RI100-series base uses delta-V detection to confirm a valid Ni-MH cell is seated. A new cell shipped at storage voltage can confuse this handshake — the base may show no charge indicator or a flashing error light. Seat the headset firmly in the cradle and leave it undisturbed for at least 90 seconds. If the indicator still does not respond, remove the pack, wait 10 seconds, reseat it, and allow the base to restart its charge detection sequence from 0V reference.

Headset cutting out mid-call even with a recently charged pack

The combined draw of the DECT radio transmitter and the audio amplifier in these compact housings creates brief current spikes that exceed what a depleted or poorly conditioned cell can supply. The BMS trips the circuit to protect the cell, and the headset drops the call. This is not a pairing fault — it is a voltage sag event. After three to five full charge-discharge cycles, internal resistance drops and the cell handles the combined load cleanly. If cutouts persist past five cycles, check that the cradle contacts are clean and making full contact with the pack terminals.