About this replacement
Sunmi V1S / V2 / P1 — 3.7V Li-ion Replacement Battery (SMBP001)
This is a 3.7V 5200mAh Li-ion battery for the Sunmi V1S, V2, P1, and W6900 payment terminals. It replaces OEM part SMBP001 (also cross-referenced as SM-INR18650M26-1S2P). If your terminal is shutting down unexpectedly or no longer holding charge through a shift, this battery restores full capacity.
- V1S, V2, P1, and W6900 compatibility: These four terminals share the same single-cell 3.7V architecture, physical form factor, and connector pinout. The BMS handshake protocol is consistent across the range, so one battery cell configuration covers all four models without firmware conflict.
- Bench tested on actual hardware: We cycled this battery through charge and discharge on a Sunmi V1S unit. The BMS accepted the cell without error flags, charge IC entered CC/CV mode normally, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
- First-cycle calibration on Sunmi terminals: After installation, complete one full transaction cycle before deploying in a live environment. The terminal maps battery capacity during normal operation and needs at least one complete power cycle to display the charge indicator correctly.
Payment terminal rebooting mid-transaction after battery swap
When a receipt prints or a barcode scan fires, the motor or laser draws a short current spike — sometimes 1.5A or more above the idle draw. On a new cell that has not yet been through a full charge cycle, the BMS can read this spike as an overcurrent event and cut the output rail. The terminal reboots, the transaction drops, and the customer sees a blank screen. Running one complete charge-discharge cycle before live deployment conditions the BMS to the terminal's actual load profile and stops false overcurrent trips.
Terminal not powering on after sitting unused in a drawer
Li-ion cells self-discharge at roughly 2–3% per month. A terminal stored for several months can drop below the BMS recovery threshold — typically around 2.5V per cell — and the protection circuit locks output to prevent damage. Plugging the charger in and leaving it for 30–60 minutes usually brings the cell back above the recovery floor. If the charge indicator stays dark past that point, check that the charger output is confirmed at 5V before assuming the battery is faulty.