About this replacement
Ascom EFT20-S — 3.6V Ni-MH Replacement Battery (MGN0319)
This is a 3.6V, 2000mAh Ni-MH replacement battery for the Ascom EFT20-S and EFT20-R portable payment terminals. It replaces OEM part MGN0319 directly. The EFT20 series runs on a single-cell Ni-MH pack at this voltage rail — swapping to anything outside that spec will cause BMS rejection or charge-IC faults.
- EFT20-S and EFT20-R compatibility: Both models share the same 3.6V battery bay, connector pinout, and BMS handshake protocol. The charge IC reads cell chemistry via the same resistance signature on both variants, so one part number covers both terminals.
- Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on the EFT20-S platform. The BMS accepted the handshake on first insertion, and the charge IC entered normal top-off mode without triggering a fault flag.
- First deployment cycle: After installing this battery, complete at least one full transaction cycle before putting the terminal into live service. The EFT20 maps charge capacity during normal operation — skipping this step leaves the charge indicator unreliable until the terminal completes its own calibration pass.
Receipt printer current spike causing mid-transaction BMS trip on the EFT20
The EFT20's onboard receipt printer draws a sharp current spike the moment it fires — this is separate from the steady-state transaction load. On a degraded or newly installed cell that hasn't completed its first calibration cycle, the BMS can read this spike as an overcurrent event and cut output to protect the cell. The terminal then reboots mid-sale, which looks like a software fault but is actually a battery protection event. Letting the terminal complete one full boot-and-print cycle before live deployment reduces false BMS trips significantly.
EFT20 not powering on after sitting unused in storage
Ni-MH cells self-discharge steadily during storage — an EFT20 left in a drawer for several months can arrive at a voltage below the BMS recovery threshold. When cell voltage drops under roughly 1.0V per cell, the BMS locks out load switching entirely and the terminal appears completely dead. Place the terminal on charge for a full uninterrupted cycle before assuming the battery is faulty. If the charge IC accepts the cell, you will see the charge indicator activate within a few minutes of connecting the dock.