About this replacement
BLU Star Jr / S350 — 3.7V Li-ion Replacement Battery (C595005142L)
This 3.7V, 1450mAh Li-ion cell replaces the original battery in the BLU Star Jr and S350 smartphones. It matches OEM part number C595005142L and fits the physical bay dimensions of both models. If your phone shuts down unexpectedly or no longer holds a charge, this is the direct cell swap.
- Star Jr and S350 compatibility: Both models run the same voltage rail and share an identical battery bay at 65.00 × 49.90 × 4.10mm with the same connector pinout and BMS handshake — one cell covers both.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the BLU S350 platform. The BMS accepted the charge handshake without fault codes, and the protection circuit triggered correctly at the low-voltage cutoff threshold.
- Fuel gauge recalibration after swap: After fitting this cell, disable fast charging and run one full discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before it starts reporting percentage to the OS — skipping this step causes erratic percentage jumps in the first few days.
Sudden shutdown at 20–30% on the BLU Star Jr after a cell swap
This happens because the fuel gauge IC is still using the discharge curve from the old, degraded cell. The new cell's actual voltage cliff sits at a different point, so the OS thinks 25% remains when the cell voltage has already dropped below what the modem and screen can sustain under load. The phone cuts power abruptly rather than tapering down. One full discharge-charge cycle at standard rate re-anchors the coulomb counter to the new cell curve and eliminates the premature cutoff.
Phone warm near the battery during the first few charges after replacement
A new high-impedance cell generates slightly more heat than a broken-in one during the initial charge cycles. The charge IC on the Star Jr pushes current at a fixed rate regardless of cell age, so internal resistance on a fresh cell produces more heat per cycle than you'd see later. This is normal for the first two or three charges and settles as internal resistance drops. If the phone stays warm after five full cycles, check that the replacement is seated flat — any gap between cell and back cover traps heat against the board.