About this replacement
ZTE Blade A520 / Blade A603 — 3.85V Li-ion Replacement Battery (Li3824T44P4H716043)
This is a 3.85V, 1500mAh Li-ion replacement battery for the ZTE Blade A520, BA520, Blade A603, BA603, and compatible variants. It carries OEM part number Li3824T44P4H716043. Fit this cell when the original no longer holds a charge or the phone shuts down unexpectedly under load.
- Blade A520 and A603 platform compatibility: Both the A520 and A603 share the same battery bay dimensions, connector orientation, and 3.85V nominal voltage rail. The BMS handshake protocol is identical across these models, so one cell covers the full list without modification.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on a Blade A603 unit. The BMS accepted the cell on first insertion, charge current ramped correctly through CC/CV stages, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.
Sudden shutdown at 20–30% on the Blade A520 after a cell swap
The Blade A520's fuel gauge IC stores a discharge curve calibrated to the original cell. A new cell with a different internal resistance profile hits a voltage cliff at a higher state of charge than the IC expects. When the modem fires up for a call or data burst, instantaneous current draw causes a voltage drop the IC reads as critical. The phone shuts off even though capacity remains. One full slow-charge cycle from 0% to 100% lets the coulomb counter rebuild its reference and the shutdowns stop.
OS reporting wrong battery percentage after replacement
Android's battery percentage on the Blade A603 reads from the fuel gauge IC, not the cell directly. The IC's learned capacity table is matched to the old cell and will misreport until it recalibrates. This shows up as the percentage jumping several points or freezing at a number before dropping suddenly. Drain the phone fully until it powers off, then charge uninterrupted to 100% with the screen off — one complete cycle resets the IC's reference points to 3.85V.