About this replacement
Resistacap Inc N250AAAF3WL — 3.6V Ni-MH Replacement Battery (CUSTOM-122)
This is a 3.6V, 700mAh Ni-MH replacement battery for the Resistacap Inc N250AAAF3WL payment terminal. It fits the N250AAAF3WL directly and restores battery-backed operation to the terminal. Voltage and connector match the original cell specification.
- N250AAAF3WL platform fit: The N250AAAF3WL uses a 3.6V Ni-MH cell with a specific connector orientation and BMS handshake tied to that voltage rail. Swapping in a cell outside that spec causes the terminal to reject the battery or loop at the boot screen. This cell matches the voltage rail and connector the terminal expects.
- Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a payment terminal test rig. The BMS accepted the handshake on first boot, charge acceptance was normal, and the terminal completed its PCI boot sequence without interruption.
- First transaction cycle after installation: Complete one full transaction cycle before deploying this terminal in a live environment. The N250AAAF3WL maps battery capacity during normal operation and needs at least one complete power cycle to calibrate the charge indicator accurately.
Terminal not completing PCI boot sequence after battery swap
The N250AAAF3WL runs a PCI security check during boot that includes a battery status read. If the BMS on the new cell hasn't completed its first handshake, the terminal can stall or loop at this screen. This isn't a fault with the cell — it's the terminal waiting for the BMS to confirm a valid charge state. Allow the terminal to complete one full charge cycle after installation. Once the cell reaches a stable charge, the boot sequence completes normally.
Battery indicator stuck at 99% after first charge
On a fresh Ni-MH cell, the charge IC in the N250AAAF3WL enters top-off mode near full capacity and holds the display at 99% for an extended period. This is normal charge controller behaviour — it's applying a trickle current to top the cell off before declaring 100%. No intervention is needed. Once the top-off phase completes, the indicator will move and stabilise at full charge.