About this replacement
Samsung Galaxy S20 / SM-G980F — 3.85V Li-Polymer Replacement Battery (EB-BG980ABY)
This is a 3.85V, 3650mAh lithium-polymer replacement battery for the Samsung Galaxy S20 and SM-G980F. It also fits the Galaxy S11e and SM-G981B, sharing the same voltage rail, connector, and BMS handshake across that hardware family. Install it when the original cell no longer holds charge or causes unexpected shutdowns.
- Galaxy S20 family compatibility: The SM-G980F and SM-G981B share the same 3.85V nominal rail, physical footprint, and BMS communication protocol — one cell fits both without modification.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on a Galaxy S20 unit. The BMS accepted charge at both standard and fast-charge rates, and protection cutoffs fired correctly at low-voltage threshold.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.
Sudden shutdown at 20–30% on the Galaxy S20 after a cell swap
This happens because the fuel gauge IC — a coulomb counter calibrated to the original cell's discharge curve — misjudges the new cell's voltage cliff. Under modem or display load, the new cell's voltage drops faster than the IC expects, triggering a hardware shutdown before the reported percentage reaches zero. It is not a defective battery. One full discharge-to-shutdown followed by an uninterrupted charge to 100% lets the IC relearn the curve. After two or three cycles, shutdown behaviour normalises.
USB-PD fast charge not working on the first cycle after replacement
On a fresh cell, the charge IC on the S20 may fall back to standard 5V charging on the first cycle while it negotiates with the new BMS. This is a handshake delay — not a fault with the cable, adapter, or battery. Disconnect the charger, wait 10 seconds, and reconnect. If fast charge still does not activate, complete one full standard charge cycle first, then retry with a USB-PD adapter delivering at least 9V/1.67A.