About this replacement
Nokia G22 / C31 — 3.85V Li-Polymer Replacement Battery (CN550)
The CN550 is a 3.85V, 5000mAh Li-Polymer cell that replaces the original battery in the Nokia G22 and Nokia C31. Both phones share the same battery bay dimensions and connector, making this a single part that covers both models. Capacity is rated at 19.25Wh from the product data.
- G22 and C31 compatibility: Nokia built both the G22 and C31 around the same 91.10 × 65.00 × 5.00mm cell footprint, same connector pinout, and the same BMS handshake voltage thresholds — so one CN550 cell covers both devices without modification.
- Bench tested on actual hardware: We cycled this cell through a full charge and discharge on the G22. The BMS accepted the charge handshake on the first cycle, cutoff triggered correctly at the low-voltage threshold, and the fuel gauge IC began tracking the new discharge curve from cycle one.
- First-cycle fuel gauge reset: After installing this cell, disable fast charging for the first complete discharge-charge cycle. The fuel gauge IC on both the G22 and C31 is calibrated against the old cell's discharge curve — one slow cycle lets it recalibrate against the new cell before high-current charging begins.
Why the Nokia G22 reports wrong battery percentage after a cell swap
The G22 uses a coulomb counter that builds its charge model over repeated cycles. When you swap the physical cell, that learned model still points to the old cell's capacity curve. The fuel gauge IC reads voltage and current against the wrong reference, so the percentage shown on screen drifts from the actual state of charge. One full slow discharge to automatic shutdown, followed by a full charge with fast charging off, resets the coulomb counter and re-anchors it to the new cell. After that cycle, percentage accuracy tightens significantly.
Sudden shutdown at 20–30% remaining on the replacement cell
This happens when the phone's modem, screen, or both spike current draw faster than the uncalibrated fuel gauge can track. The cell voltage dips below the BMS cutoff threshold before the OS has time to trigger a controlled shutdown — so the phone just cuts out. It is not a faulty cell; it is the coulomb counter reporting a higher state of charge than the cell can sustain under load. Run one full discharge-charge cycle with fast charging disabled. Once the fuel gauge IC has mapped the real discharge curve of the CN550, the early-shutdown behaviour stops.