About this replacement
Seecode Vossor Phonebook / Mirrow III — 3.7V Li-ion Replacement Battery (NP120)
This is a 3.7V, 1700mAh Li-ion replacement battery for the Seecode Vossor Phonebook, Vossor Plus, Mirrow III, and Mirrow 3. It uses OEM part number NP120 and fits the physical and electrical spec of the original cell. Capacity figure is taken directly from the product specification — 1700mAh (6.29Wh).
- Vossor and Mirrow series compatibility: These models share the same battery bay dimensions, 3.7V nominal rail, and NP120 connector pinout. The BMS handshake is identical across the Vossor Phonebook, Vossor Plus, Mirrow III, and Mirrow 3 — one cell fits all four.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Vossor Phonebook. The BMS accepted the cell without error flags, held stable voltage under continuous recording load, and triggered protection cutoff at the correct low-voltage threshold.
- First-use charge before any recording session: Digital recorders write audio continuously to flash storage. An unexpected power cut mid-session corrupts the active file. Charge this cell fully before the first session — the recorder needs a stable voltage ceiling before it starts writing.
Recording stopping mid-session on the Vossor Phonebook
The Vossor Phonebook requires a minimum sustained voltage to keep the recording engine and flash write cycle active. As a Li-ion cell ages, its voltage under load drops faster than the open-circuit reading suggests. When the cell sags below the recorder's minimum operating threshold mid-session, the firmware cuts the write process. The result is a truncated file — audio up to the cutoff point is usually recoverable, but the session ends without a clean close. A fresh NP120 cell holds the voltage rail flat long enough to complete normal-length sessions without sag-triggered cutoffs.
Recorder won't start after a new battery is installed
This happens when the replacement cell ships at storage voltage — typically around 3.6V — and the Vossor Phonebook's boot threshold sits just above that. The device attempts to start, the BMS sees marginal voltage, and the unit shuts back down or shows nothing on screen. It is not a faulty battery. Connect the charger first and bring the cell to at least 3.8V before pressing power. The recorder boots cleanly once the cell clears the boot voltage floor.