About this replacement
BLU Studio 7.0 II — 3.8V Li-Polymer Replacement Battery (C1028703345L)
This 3.8V, 3450mAh Li-Polymer cell replaces the OEM battery in the BLU Studio 7.0 II and compatible variants including the U48OU, S490U, and U480U. It powers the phone's processor, display, and cellular radio. Capacity is sourced from the product specification, not estimated from web data.
- Studio 7.0 II, U48OU, S490U, U480U compatibility: These four models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The C1028703345L fits all four without modification to the connector or housing.
- Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on the Studio 7.0 II platform. The BMS accepted the cell without a low-voltage rejection flag, and the fuel gauge IC initialised correctly on the first cycle.
- First-cycle fast charge tip: On first use after installation, disable fast charging and complete one full discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging is applied to an uncalibrated cell.
Sudden shutdown at 20–30% on the Studio 7.0 II after a cell swap
The Studio 7.0 II's fuel gauge IC stores a discharge curve calibrated to the original cell. When a new cell goes in, the IC still references the old curve. At roughly 20–30% reported charge, the new cell's actual voltage drops below what the modem and display need to sustain operation — but the IC hasn't flagged it yet. The phone shuts down before the gauge reaches zero. One complete discharge-to-shutdown followed by an uninterrupted charge to 100% forces the IC to write a new curve against the replacement cell. After that cycle, the percentage readout tracks the actual cell voltage correctly.
Device not powering on after the replacement cell sat in storage
Li-Polymer cells self-discharge in storage, and if the C1028703345L dropped below approximately 2.5V per cell before installation, the BMS enters a lockout state to prevent a deep-discharge charge event. The phone will show nothing on screen — no charge indicator, no vibration. Connect the phone to a wall charger rated at 5V/1A and leave it for 20–30 minutes without pressing any buttons. The BMS recovery circuit trickle-charges the cell back above the lockout threshold, after which normal charging resumes and the phone powers on.