Samsung B450BU Galaxy Ace 2 Compatible Battery 3.7V 1550mAh

Samsung Galaxy Ace 2 / SM-G730 Series — 3.7V Li-ion Replacement Battery (B450BU)

This 3.7V, 1550mAh Li-ion cell replaces the OEM B450BU, B450BC, B450BE, and B450BZ batteries. It fits the Samsung GT-I1819 (Galaxy Ace 2), SM-G730, SM-G730A, SM-G3518, and nine additional variants on the same platform. Capacity is 1550mAh (5.74Wh), matching the original specification.

• GT-I1819 and SM-G730 platform compatibility: These models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The B450BU part number spans all variants, so one cell covers the full GT-I1819 and SM-G730 production run without modification.
• Bench tested on actual hardware: We cycled this cell on a GT-I1819 unit and monitored the charge IC handshake. The BMS accepted the charge signal on the first connection, held voltage above 3.5V under display-plus-modem load, and completed a full charge cycle without interruption.
• Fuel gauge recalibration on first use: Disable fast charging for the first complete discharge-charge cycle after installation. The fuel gauge IC on the GT-I1819 is calibrated to the old cell's discharge curve. One full cycle at standard current lets it map the new cell before high-current charging pushes into an uncalibrated state.

Sudden shutdown at 20–30% on the GT-I1819 after a cell swap

The GT-I1819 shuts down abruptly at 20–30% because the modem and display together pull enough current to cause a rapid voltage drop in an aged or uncalibrated cell. A new cell can trigger the same behaviour on the first few cycles if the fuel gauge IC still holds the old cell's internal resistance model. The phone cuts power when terminal voltage dips below roughly 3.4V under that combined load — even though the coulomb counter still shows charge remaining. Run one full discharge to the auto-off point, then charge uninterrupted to 100% to force the fuel gauge to relearn the new cell's voltage-versus-capacity curve.

Phone won't power on after the replacement cell sat in storage

Li-ion cells self-discharge in storage at roughly 1–3% per month. If the B450BU cell arrived or was stored in a discharged state for an extended period, terminal voltage may have dropped below 2.5V — the BMS lockout threshold. At that point the BMS disconnects the cell to prevent damage, and the phone shows no response to the power button. Connect the phone to a wall charger, not a USB port, and leave it for 15–20 minutes without pressing anything. The charge IC applies a trickle pre-charge current to recover the cell voltage above the 2.5V BMS re-enable threshold before normal charging resumes.