Samsung Galaxy Mega 5.8 B650AE Replacement Battery 3.8V 2600mAh

Samsung Galaxy Mega 5.8 / GT-I9150 — 3.8V Li-ion Replacement Battery (B650AE)

This is a 3.8V, 2600mAh Li-ion cell replacing the OEM B650AE battery in the Samsung Galaxy Mega 5.8 and Galaxy Mega Duos. It fits GT-I9150 and GT-I9152 variants along with 17 additional model numbers sharing the same battery bay and connector. If the original cell is swollen, draining fast, or not charging past a low percentage, this is the direct swap.

• GT-I9150 and GT-I9152 compatibility: Both the single-SIM Mega 5.8 and the Duos dual-SIM variant use the same B650AE footprint — same 63.05 × 56.82 × 5.25mm cell, same three-tab connector, same BMS pinout. No adapter or modification needed.
• Bench tested on actual hardware: We ran the cell through charge and discharge cycles on a GT-I9150 unit. The BMS accepted charge current from the device's charge IC without fault flags. Capacity read within expected tolerance of the rated 2600mAh.
• Fuel gauge recalibration on first use: Disable fast charging in settings for the first full discharge-charge cycle after installation. The fuel gauge IC on the Mega 5.8 was calibrated to the old cell's discharge curve — letting it recalibrate against the new cell under a standard charge rate prevents erratic percentage readings from the first day.

Sudden shutdown at 20–30% on the Galaxy Mega 5.8

This happens when an aged cell can no longer hold voltage under the combined load of the large 5.8-inch display and the modem radio. The phone's power management IC sees the voltage drop below its cutoff threshold — even though the fuel gauge still shows charge remaining. It is a voltage cliff, not a capacity problem. A new cell with lower internal resistance sustains voltage under that combined load, pushing the actual cutoff point back toward 0% where it belongs.

Phone won't power on after sitting in storage with a flat battery

If the replacement or old cell discharged below roughly 2.5V per cell during storage, the BMS enters a lockout state and blocks normal charge current. Plug the phone into a charger and leave it connected for 20–30 minutes without pressing the power button — the charge IC will trickle current into the cell until it crosses the BMS re-enable threshold. Once voltage recovers above that threshold, the phone will boot normally. If it still won't respond after 30 minutes, check the charger is delivering at least 5V with a multimeter at the cable tip.