About this replacement
VeriFone CM5P / Carbon Mobile 5 — 3.7V Li-ion Replacement Battery (BPK278-502)
This is a 3.7V, 6800mAh Li-ion battery for the VeriFone CM5P and Carbon Mobile 5 mobile payment terminals. It fits both OEM part numbers BPK278-502 and BPK278-502-01-A. The cell capacity matches the original specification to keep the terminal running through a full business shift.
- CM5P and Carbon Mobile 5 fit: Both models share the same battery bay, connector pinout, and BMS handshake protocol — the same cell works across the entire platform without any modification.
- Bench tested on actual hardware: We cycled this battery through a full boot sequence on the CM5P, including wireless pairing and receipt print events. The BMS accepted the charge state without any fault flags.
- First-deployment tip for POS terminals: After installing this battery, run at least one complete transaction cycle — card read, wireless auth, and print — before putting the terminal into live use. The CM5P maps battery capacity during normal operation and needs that cycle to display charge level correctly.
Terminal not completing PCI boot sequence after battery swap
The CM5P runs a PCI-mandated power-on self-test that checks for a stable voltage rail before releasing the OS. A freshly installed cell may sit at a surface charge that the BMS hasn't yet validated, causing the terminal to stall at the boot screen. This is a handshake timing issue, not a fault with the battery itself. Charge the battery to full via the terminal — not an external charger — and allow one complete boot-charge cycle to complete.
Battery indicator stuck at 99% after first charge
New lithium-ion cells arrive with a partial factory charge, which puts the CM5P's charge IC into top-off mode rather than a full charge cycle. The indicator holds at 99% because the controller hasn't recorded a complete charge event to anchor its capacity map. Let the terminal charge uninterrupted from below 20% to a full green status — this gives the charge IC the data it needs. After that first full cycle, the percentage will track accurately.