Sharp SHBAJ1 904SH Replacement Battery 3.7V 900mAh

Sharp 904SH / V904SH — 3.7V Li-ion Replacement Battery (SHBAJ1)

This is a 3.7V Li-ion replacement battery rated at 900mAh (3.33Wh) for the Sharp 904SH and V904SH smartphones. It matches the OEM SHBAJ1 specification and fits the original battery bay without modification. If your 904SH drops charge fast or won't hold a charge at all, this cell replaces the aged original.

• 904SH and V904SH compatibility: Both variants run the same 3.7V single-cell architecture with an identical connector pinout and BMS handshake protocol. One replacement cell covers both models.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the 904SH platform. The BMS accepted the cell without fault codes, and the charge IC completed a full cycle to 4.2V without throttling.
• Fuel gauge recalibration on first use: After fitting this cell, disable any fast-charge setting and run one complete discharge-to-charge cycle at standard current. This gives the fuel gauge IC time to map the new cell's discharge curve before higher current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the 904SH after cell replacement

This happens when the fuel gauge IC is still running a discharge curve calibrated to the old, degraded cell. The new cell has a steeper voltage drop under modem or display load, and the phone interprets that voltage sag as a critically low state. The device shuts down even though actual remaining capacity is higher. One full uninterrupted discharge-charge cycle resets the coulomb counter and corrects the percentage estimate going forward.

Phone not powering on after the SHBAJ1 has been sitting in storage

Li-ion cells in storage self-discharge slowly. If the cell drops below roughly 2.5V, the BMS enters lockout to prevent damage and blocks the normal boot sequence. Plugging in a charger may show no response for several minutes — this is the charge IC trickling current into the cell at a safe pre-charge rate. Leave the phone connected for at least 15–20 minutes before attempting a power-on. Once the cell climbs back above 3.0V, the BMS releases and the phone should boot normally.