About this replacement
Simolio SM-823 Series — 3.7V Li-Polymer Replacement Battery (SM-001BAT)
This is a 3.7V, 300mAh lithium-polymer replacement battery for the Simolio SM-823 wireless headset range. It fits the SM-823, SM-823D, SM-8245, SM-863D, and six additional models in the same family. Swap it in when the original cell no longer holds a charge or the headset dies sooner than expected.
- SM-823 family fit: All listed models share the same voltage rail, physical cell dimensions (40.00 × 21.70 × 5.80mm), and BMS handshake protocol — that is why one part number covers the full range.
- Bench tested on actual hardware: We cycled this cell through the SM-823 base station and confirmed the BMS completed its handshake correctly. The headset registered as charging and the base station showed no error codes after the first full charge cycle.
- First-charge protocol for DECT headsets: Seat the headset in the base station and let it complete one uninterrupted charge cycle before taking a call. The base needs to log the new cell before its talk-time counter reads accurately — skipping this step causes the indicator to under-report remaining charge.
Why the SM-823 cuts out mid-call on a new battery
The SM-823 draws current from two simultaneous loads — the audio driver and the DECT radio transmitter. Under combined draw, a cell sitting at storage voltage (typically around 3.6–3.7V, not fully charged) cannot sustain the instantaneous current spike. The BMS interprets this as a low-cell event and trips the cutoff. One full charge cycle from the base station before first use brings the cell to its actual rated capacity and prevents this trip.
Base station shows full charge but headset cuts off after a few seconds
This is a storage-voltage symptom, not a faulty cell. A new lithium-polymer cell ships at roughly 50% charge to stay within safe transport voltage limits. If the base station's charge indicator reads full before the cell has actually completed a cycle, the firmware has not recalibrated to the new cell's capacity. Place the headset back in the base, leave it for a complete uninterrupted charge, then test again. The cutoff threshold for this cell is 3.0V — anything above that after a full cycle means the cell is functioning correctly.