About this replacement
BLU Studio 5.0S / D572A / Y530Q — 3.7V Li-ion Replacement Battery (C665104200T)
This is a 3.7V, 1800mAh Li-ion cell that replaces the original battery in the BLU Studio 5.0S, D572A, Y530Q, and Studio 5.0 S II. It fits the same slot and connector as the factory cell. Use the OEM part numbers C665104200T and C765804200L to confirm fitment before ordering.
- Studio 5.0S / D572A / Y530Q compatibility: These models share the same battery bay dimensions (72.00 × 56.90 × 4.50mm), connector pinout, and BMS handshake protocol — one cell covers the full group without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a Studio 5.0S unit. The BMS accepted the cell without a fault code, and the charge IC held the correct 4.2V termination voltage at end of charge.
- Fuel gauge recalibration on first use: Disable fast charging for your first complete discharge-charge cycle after installation. The fuel gauge IC on this phone calibrates its coulomb counter against the new cell's discharge curve — running a slow cycle first prevents the gauge from locking onto an incorrect baseline that causes erratic percentage readings later.
Sudden shutdown at 20–30% on the Studio 5.0S
This is a voltage cliff issue, not a capacity issue. When the modem transmits or the screen brightness spikes, current draw pulls the cell voltage down sharply. If the cell cannot hold voltage above the BMS cutoff threshold under that load, the phone shuts off even though the fuel gauge still shows charge remaining. A fresh cell with low internal resistance holds voltage through those draw spikes. After fitting this replacement, run one full discharge cycle so the fuel gauge IC maps the new cell's actual voltage curve before drawing conclusions about battery health.
Phone not powering on after the replacement battery sat in storage
Li-ion cells in storage self-discharge over time. If the cell drops below approximately 2.5V, the BMS enters a lockout state and will not allow a normal charge current to flow. The phone appears completely dead — no charge indicator, no boot. Connect the phone to a low-current USB charger (a wall adapter, not a PC port) and leave it for 20–30 minutes without pressing any buttons. The charge IC will trickle current into the cell until it clears the BMS lockout threshold, at which point normal charging resumes. If the charge indicator still does not appear after 40 minutes, check the USB cable and adapter output — confirm the adapter delivers at least 5V/1A.