Sharp V604SH SHBAF1 Replacement Battery 3.7V 550mAh

Sharp V604SH — 3.7V Li-ion Replacement Battery (SHBAF1)

This is a 3.7V Li-ion cell rated at 550mAh (2.04Wh), built to the SHBAF1 specification. It fits the Sharp V604SH mobile phone. Use it when the original cell no longer holds charge or the phone shuts down unexpectedly under load.

• V604SH fit: The V604SH uses a compact single-cell Li-ion pack at 3.7V nominal. This replacement matches the original connector pinout and cell dimensions (40.39 × 35.78 × 5.74mm), so the BMS handshake with the phone's charge IC completes without errors.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS held the charge termination voltage correctly and did not trip on a cold-start draw. No voltage sag outside expected range for a 550mAh cell.
• Fuel gauge recalibration on first install: Disable fast charging for the first complete discharge-charge cycle after fitting this cell. The fuel gauge IC on the V604SH calibrates its coulomb counter against the new cell's discharge curve — skipping this step lets fast current push into an uncalibrated gauge, causing percentage drift for weeks.

Sudden shutdown at 20–30% on the V604SH after a cell swap

This happens because the fuel gauge IC still holds the discharge curve from the old, degraded cell. The new cell has a steeper voltage cliff at low charge — the phone reads 25% but the actual cell voltage under modem transmit load drops below the shutdown threshold. The fix is one full discharge-charge cycle with the screen at normal brightness and mobile data active. After that cycle, the coulomb counter resets against the real curve and the shutdowns stop.

Phone not powering on after the SHBAF1 cell sat in storage

Li-ion cells stored uncharged self-discharge over time. If the cell voltage drops below approximately 2.5V, the BMS enters lockout to prevent cell damage and will not pass current to the phone. The V604SH will show no response — no boot screen, no charge indicator. Connect to a charger and leave it for 20–30 minutes before attempting to power on; the charge IC needs to trickle current into the cell until it clears the BMS lockout threshold, typically around 3.0V.