Geenk G3 Payment Terminal Compatible Battery 3.87V 5000mAh

Geenk G3 — 3.87V Li-Polymer Replacement Battery

This 3.87V 5000mAh Li-Polymer battery fits the Geenk G3 payment terminal. It restores power to portable POS devices used in retail and mobile merchant environments. No OEM part number is published for this cell — the G3 draws from a single internal battery bay with a direct connector to the main board.

• G3 terminal fit: The Geenk G3 uses a single Li-Polymer cell matched to a 3.87V nominal voltage rail. The BMS on the main board monitors cell voltage and temperature directly — any replacement must sit within that voltage spec or the charge IC will refuse to initialise.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the G3 platform. The BMS accepted the handshake on first boot, the charge indicator stepped through correctly, and the cell held stable voltage under combined display, wireless, and printer load.
• First deployment tip: After fitting, complete one full transaction cycle before going live. The G3 maps battery capacity during normal operation and needs at least one complete power cycle to calibrate the charge indicator — skipping this leaves the gauge stuck or inaccurate in the first shift.

Terminal not completing PCI boot sequence after battery swap

The G3 runs a PCI compliance check during every boot. A freshly installed cell sometimes sits at a voltage the BMS flags as uncertain — not low enough to refuse power, but not high enough to pass the internal health assertion the boot sequence checks. The terminal stalls or loops before reaching the home screen. Charge the replacement cell to full before the first boot, and let the terminal complete one uninterrupted power cycle. That brings the cell above the 4.1V threshold the BMS expects to see before clearing the boot sequence.

Battery indicator stuck at 99% through the first charge

New Li-Polymer cells ship at a storage charge, not a full charge. When the G3 charge IC sees a cell already above roughly 80% state-of-charge, it enters top-off mode — a low-current trickle that can hold the display at 99% for an extended period before the final step completes. This is the charge IC behaving correctly, not a fault with the cell. Leave the terminal on charge until the indicator clears to 100% and the charging LED changes state — that confirms the top-off cycle finished and the full 5000mAh capacity is available.