About this replacement
Sunmi P2 / T6900 — 7.6V Li-Polymer Replacement Battery (2ICP5/58/84)
This is a 7.6V, 2500mAh Li-Polymer battery for the Sunmi P2 and T6900 portable payment terminals. It replaces part number 2ICP5/58/84 and fits the original battery bay without modification. Capacity and voltage match OEM spec exactly — 19Wh total energy.
- P2 and T6900 compatibility: Both terminals share the same 7.6V battery platform, connector pinout, and BMS handshake protocol. A single cell design covers both units because the charge IC and communication lines are electrically identical across the two models.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on a P2 unit. The BMS accepted the handshake on first boot, charge IC entered CC/CV mode correctly, and the protection circuit tripped as expected under a simulated overcurrent load.
- First-deployment cycle tip: After fitting this battery, run one complete transaction — card read, receipt print, and screen wake — before putting the terminal into live service. The P2 maps cell capacity during normal operation, not during idle charging, so the charge indicator will not settle until the device completes at least one active power cycle.
Why the P2 reboots mid-transaction after a battery swap
The P2's receipt printer draws a short, sharp current spike when the paper feed motor engages. On a new cell that hasn't completed its first full charge cycle, the BMS can read this spike as an overcurrent event and cut output to protect the cell. This trips a hard reboot rather than a graceful shutdown. To clear it, charge the battery to 100%, then run two or three test transactions so the BMS learns the printer's current signature and stops flagging it as a fault.
Terminal stuck on boot screen and not completing PCI sequence
The Sunmi P2 runs a PCI security boot check that requires stable voltage from the battery before it releases the OS to load. If the replacement cell ships at a low state of charge, voltage at the battery terminals can sag below the threshold the boot sequence expects — typically around 7.0V under load — causing the device to stall or loop. Plug the terminal into charge before powering it on and let it reach at least 20% before attempting a boot. A full charge to 8.4V clears the condition entirely.