About this replacement
Brondi Smartphone S — 3.8V Li-Polymer Replacement Battery (S572)
This is a 3.8V, 2900mAh Li-Polymer battery for the Brondi Smartphone S (OEM part S572). It replaces the original cell when the phone no longer holds adequate charge. Voltage, capacity, and connector match the factory specification.
- Brondi Smartphone S fit: The S572 part number covers the Smartphone S platform. The connector orientation, BMS handshake voltage, and physical footprint — 84.00 × 60.00 × 4.20mm — are specific to this model. No modification needed to fit the battery compartment.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Smartphone S platform. The BMS accepted the cell without error flags, and the charge IC ramped normally through CC and CV phases to full termination voltage.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.
Why the Brondi Smartphone S reports wrong battery percentage after a cell swap
The fuel gauge IC builds its percentage model from the discharge curve of the original cell over many cycles. When a new cell goes in, the stored curve no longer matches actual cell behaviour. The result is a percentage reading that jumps, stalls, or reads 100% then drops suddenly. One full discharge-charge cycle lets the coulomb counter reset its reference and re-anchor the percentage to the new cell's actual capacity.
Sudden shutdown at 20–30% remaining on the Brondi Smartphone S
This is a voltage cliff — the cell voltage drops below the threshold the modem and display require under peak load, even though the fuel gauge still shows charge remaining. It happens most often when the fuel gauge IC is still calibrated to the old, degraded cell. The BMS trips to protect the cell before the OS can complete a clean shutdown. Run one full discharge to 0% (phone-reported) followed by a full charge to let the fuel gauge recalculate the low-voltage cutoff point against the new cell.