About this replacement
3M C960 Headset Series — 1.2V Ni-MH Replacement Battery (175T17NO09)
This 1.2V, 1500mAh Ni-MH cell replaces the original rechargeable pack in the 3M C960 Headset, C860 Beltpack, and C1025 Transceiver. It restores wireless operation to headsets where the original cell has degraded after repeated charge cycles. Capacity is 1.8Wh, matching the OEM specification.
- C960, C860, and C1025 compatibility: These three units share the same 1.2V Ni-MH cell format, connector pinout, and base station charging circuit. Swapping the pack across this group works because the base charges by voltage curve, not by a BMS handshake that would reject a third-party cell.
- Bench tested on actual hardware: We cycled this cell through the C960 base station and confirmed the charging LED sequence completed normally. The base reached trickle-charge cutoff without throwing an error, and the headset registered a full charge state before pairing was re-established.
- Base station logging on first install: On first use, seat the headset in the base and let it complete a full uninterrupted charge cycle before making a call. DECT headsets use the base to calibrate the talk-time estimate against the new cell — taking it off the base early leaves that estimate inaccurate for several cycles.
Base station showing full charge but headset cuts off after a short call
A fresh Ni-MH cell ships at storage voltage — typically around 1.0V per cell — which is below the operating floor the headset's audio and DECT radio circuits expect under combined draw. The base station may display a full charge indicator before the cell has actually completed its first full cycle. Until that first cycle finishes, the cell cannot sustain the current spike when the DECT radio transmits. Let the headset sit in the base for a complete charge cycle, then discharge it fully on a call before recharging — this brings the cell to its rated 1500mAh capacity.
Headset cutting out mid-call after the battery is already broken in
Ni-MH cells are sensitive to shallow-cycle degradation — if the headset is regularly topped up after short calls without being fully discharged, the cell develops a reduced effective capacity over time. The combined draw of the audio amplifier and DECT radio transmission causes a brief voltage sag that drops below the headset's cutoff threshold, even when the charge indicator shows capacity remaining. The fix is a deliberate full discharge-recharge cycle: use the headset until it powers off on its own, then charge uninterrupted to 100%. Repeat this two to three times to recover usable capacity toward the rated 1.2V operating level.