About this replacement
BLU Sport 4.5 / Dash 4.5 — 3.7V Li-ion Replacement Battery (C604906200L)
This is a 3.7V, 2000mAh Li-ion battery for the BLU Sport 4.5, S430L, S430U, and Dash 4.5 smartphones. It replaces OEM part numbers C604906200L and C604905200T. Rated at 7.4Wh with a cell footprint of 60.15 × 49.08 × 5.80mm.
- Sport 4.5 and Dash 4.5 platform fit: The S430L and S430U share the same physical battery bay, connector pinout, and BMS handshake as the Dash 4.5 variant. One cell format covers both sub-lines because BLU used the same internal chassis across this 4.5-inch entry series.
- Bench tested on actual hardware: We cycled this cell on an S430 unit and confirmed the BMS accepted the new cell without error flags. Charge acceptance was clean from first insertion, and the protection circuit responded correctly to both low-voltage and overcharge thresholds.
- Fuel gauge recalibration on first cycle: After fitting this cell, disable fast charging if your charger supports it and run one full discharge down to automatic shutoff, then charge to 100% uninterrupted. The fuel gauge IC in the Sport 4.5 calibrates its coulomb counter against the cell's discharge curve on that first full cycle — skipping it causes erratic percentage readings for the first several days of use.
Why the Sport 4.5 reports wrong battery percentage after a cell swap
The BLU Sport 4.5 uses a fuel gauge IC that stores a learned discharge model for the cell it has been running. When you swap in a new cell, that stored model no longer matches the new cell's actual voltage-to-capacity curve. The IC keeps reporting against the old curve until it completes at least one full discharge-charge cycle on the new cell. Until recalibration happens, the percentage display can read 20% ahead or behind actual state of charge. One uninterrupted full cycle — from automatic low-battery shutoff to 100% — resets the learned curve.
Sudden shutdown at 20–30% on the replacement cell
This happens when the fuel gauge IC has not yet recalibrated and the displayed percentage does not reflect the cell's real remaining charge. Under modem or screen load, the cell voltage can drop sharply past the BMS cutoff threshold even though the display still shows 20–30% remaining. The protection circuit sees the voltage sag below approximately 3.0V per cell and triggers an immediate shutoff to protect the cell. The fix is the same recalibration cycle — one full discharge to automatic shutoff, then a full uninterrupted charge to 100%.