About this replacement
Sunmi P2 Mini — 3.8V Li-ion Replacement Battery (FR020)
This 3.8V, 2500mAh Li-ion battery replaces the original FR020 cell in the Sunmi P2 Mini payment terminal. It fits the compact P2 Mini form factor directly, using the same 65.50 x 58.00 x 5.30mm dimensions as the factory unit. Merchants running the P2 Mini for card payments install this when the original cell no longer holds charge through a shift.
- P2 Mini platform fit: The P2 Mini uses a fixed voltage rail at 3.8V with a proprietary connector and BMS handshake. This cell matches that spec. Swapping a mismatched voltage cell trips the protection circuit and the terminal won't boot.
- Bench tested on actual hardware: We cycled this cell through the P2 Mini's charge IC and confirmed the BMS accepted the handshake without fault flags. The charge controller entered top-off mode correctly at full capacity.
- First deployment tip: After installation, run one complete transaction cycle before deploying in a live environment. The P2 Mini maps battery capacity during normal operation and needs at least one full power cycle to calibrate the charge indicator correctly.
Why the P2 Mini reboots mid-transaction after a battery swap
The P2 Mini's receipt printer draws a short current spike when it fires — often 1.5A or more for a fraction of a second. On a new cell that hasn't completed a full charge-discharge cycle, the BMS can read that spike as an overcurrent event and cut output. The terminal reboots. Running one full transaction cycle after installation lets the BMS learn the device's normal draw profile and stop tripping on printer pulses.
Terminal not powering on after sitting unused in a drawer
Li-ion cells that sit uncharged for weeks can drop below the BMS recovery threshold — typically around 2.5V to 2.7V per cell. Below that, the protection circuit blocks output entirely as a safety measure and the terminal shows nothing on screen. Connect the original Sunmi charger and leave it for 20–30 minutes without pressing any buttons; the charge IC will attempt a trickle pre-charge to bring the cell above 3.0V before resuming normal charging.