About this replacement
BLU Star 4.5 / S450 — 3.7V Li-ion Replacement Battery (C635404170L)
This is a 3.7V, 1550mAh Li-ion cell that fits the BLU Star 4.5 and S450 smartphones. It replaces OEM part C635404170L and restores power to a phone that no longer holds charge or shuts down unexpectedly. Capacity is 5.74Wh — matched to the original spec.
- Star 4.5 and S450 compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The cell measures 63.05 × 54.05 × 4.60mm — a match to the factory cavity on both variants.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a BLU S450 unit. The BMS accepted the charge IC handshake without faults, and the fuel gauge IC tracked state-of-charge correctly after one full conditioning cycle.
- Fuel gauge recalibration on first install: After fitting this cell, disable fast charging and run one complete discharge down to auto-shutoff, then charge uninterrupted to 100%. This lets the fuel gauge IC map its reference curve to the new cell before high-current charging begins.
Sudden shutdown at 20–30% on the BLU Star 4.5
This happens when the fuel gauge IC is still calibrated to the old cell's discharge curve. The replacement cell hits a voltage cliff under modem or display load before the OS percentage reading reaches zero. The phone interprets the voltage drop as a hard fault and cuts power. One full discharge-to-shutoff cycle followed by an uninterrupted charge to 100% forces the coulomb counter to reset its reference points against the new cell.
OS reporting wrong battery percentage after cell swap
The fuel gauge IC stores a learned discharge profile from the old cell. A new cell with different internal resistance throws that profile off immediately. You'll see the percentage jump erratically or read higher than actual. Run one full cycle — discharge to auto-shutoff, charge to 100% with the screen off — and the coulomb counter recalibrates. After that cycle, percentage reporting stabilises.