Seecode S30 Compatible Battery 3.7V 900mAh Li-ion

Seecode S30 — 3.7V Li-ion Replacement Battery

This 3.7V, 900mAh Li-ion cell replaces the original battery in the Seecode S30 smartphone. It fits the S30's battery bay directly and restores power to devices where the original cell has degraded or failed. Capacity is 900mAh (3.33Wh) — matching the S30's stock specification.

• S30 platform fit: The S30 uses a compact 53.00 × 34.00 × 4.30mm cell format with a 3.7V nominal rail. This replacement matches those physical and electrical requirements, so the connector seats correctly and the charge IC sees the expected voltage range on first power-up.
• Bench tested on actual hardware: We cycled this cell through full charge and load discharge on the bench. The BMS held charge cutoff at 4.2V and engaged protection below 3.0V under sustained load — both within expected Li-ion operating bounds for this cell class.
• First-cycle fast charge tip: On the S30, disable fast charging for the first complete discharge-charge cycle after fitting this cell. The fuel gauge IC needs one full cycle against the new cell's discharge curve before it can calibrate accurately — running fast charging into an uncalibrated cell pushes current before the IC knows where the voltage cliff sits.

Why the S30 reports wrong battery percentage after a cell swap

The S30's fuel gauge IC builds its capacity model from the previous cell's charge and discharge history stored in the coulomb counter. When you fit a new cell, that stored model no longer matches the new cell's actual discharge curve. The phone reads voltage and maps it against the old curve, so the percentage shown drifts from reality — often reading 100% prematurely or dropping sharply near the bottom. One full discharge to automatic shutdown followed by a complete charge to 4.2V resets the coulomb counter against the new cell and restores accurate reporting.

Sudden shutdown at 20–30% remaining on the replacement cell

This happens when the modem or display draws a short, high-current burst and the cell voltage drops below the BMS cutoff threshold before the OS can react — a voltage cliff the fuel gauge didn't predict. It's most common before the coulomb counter has recalibrated to the new cell. The fix is the same full discharge-recharge cycle described above. If shutdowns persist past two full cycles, check that the replacement cell contacts are seated firmly — poor contact raises impedance and worsens voltage sag under load.