About this replacement
HTC Mini BL R120 Bluetooth Media Handset — 3.7V Li-Polymer Replacement Battery (BN02100)
This is a 3.7V, 300mAh Li-Polymer replacement battery for the HTC Mini BL R120 Bluetooth media handset. It replaces OEM part BN02100 and fits directly into the R120 handset housing. Use this when the original cell no longer holds a charge or the headset cuts off mid-call without warning.
- HTC Mini BL R120 fit: The R120 runs its Bluetooth radio and audio codec on a single 3.7V cell. This battery matches the OEM voltage rail, physical footprint (38.70 × 21.60 × 4.10mm), and connector orientation — no modifications needed.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the R120 platform. The BMS completed the handshake with the base station correctly and reported charge state without fault flags.
- First-cycle conditioning on the R120: Place the handset in the base station and let it complete one full charge cycle before making any calls. The base station uses that first cycle to log the new cell and calibrate the talk-time indicator — skipping it means the charge display will read inaccurately for several sessions.
Why the R120 cuts out mid-call even with a charged battery
The R120 draws on the battery simultaneously for the Bluetooth radio and audio output. Under that combined load, a degraded or deeply discharged cell can sag below the BMS cutoff threshold even when the indicator showed charge remaining. The BMS shuts the output to protect the cell — the headset goes silent. A fresh cell with full capacity holds the voltage above that threshold throughout a normal call.
Base station shows full charge but headset dies after a few seconds
This happens when a new cell arrives at storage voltage — typically around 3.6V — and the base station tops it up just enough to report full without completing a true charge cycle. The cell hasn't been conditioned and the BMS hasn't logged accurate capacity data. The fix is to leave the handset docked for a complete uninterrupted charge cycle. After that cycle, the base station charge indicator and actual run capacity will align.