I-Mate SP JAS BERR160 Replacement Battery 3.7V 1250mAh

I-Mate SP JAS — 3.7V Li-Polymer Replacement Battery (BERR160)

This 3.7V 1250mAh Li-Polymer cell replaces the original battery in the I-Mate SP JAS smartphone. It fits the SP JAS directly and matches the OEM voltage and connector layout. Capacity is rated at 4.63Wh — identical to the factory specification.

• SP JAS platform fit: The SP JAS uses a single-cell Li-Polymer pack with a low-profile connector and a thin 5.94mm cell envelope. This replacement matches that form factor exactly — same cell dimensions at 64.58 x 41.71 x 5.94mm — so the battery cover seats flush without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SP JAS platform. The BMS accepted the cell on first connection, charge current ramped normally, and the protection circuit tripped correctly at low-voltage cutoff with no unexpected shutdowns during the test cycle.
• Fuel gauge recalibration after swap: On first use after installing this cell, disable fast charging if available and run one full discharge down to auto-shutdown, then charge uninterrupted to 100%. This gives the SP JAS fuel gauge IC one complete cycle to map the new cell's discharge curve before reporting accurate percentages.

Why the SP JAS reports wrong battery percentage after a cell swap

The SP JAS tracks charge state using a fuel gauge IC that builds its model against the old cell's discharge curve over many cycles. When a new cell goes in, that learned curve no longer matches the actual cell chemistry. The IC reports percentage based on stale data, so the display shows values that don't reflect real charge state. One full uninterrupted discharge-to-shutdown followed by a complete charge forces the IC to reset its coulomb counter reference and re-anchor to the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or screen draws peak current and the cell voltage drops faster than the fuel gauge predicts — crossing the low-voltage cutoff before the displayed percentage reaches zero. The BMS cuts power to protect the cell, and the phone shuts off mid-use with charge still showing on screen. The fix is that same first-cycle full discharge — let the phone run completely to shutdown naturally, then charge to 100% without interruption. After one full cycle, the fuel gauge recalibrates its voltage-to-percentage mapping and the shutdowns stop.