About this replacement
Samsung Galaxy Note 20 Ultra — 3.87V Li-Polymer Replacement Battery (EB-BN985ABY)
This is a 3.87V, 4200mAh (16.25Wh) Li-Polymer replacement battery for the Samsung Galaxy Note 20 Ultra and Note 20 Ultra 5G. It fits SM-N985T, SM-N985, and 18 additional regional variants that share the EB-BN985ABY cell specification. OEM part number GH82-23333A covers the same cell across Samsung's official service assembly.
- Note 20 Ultra and 5G variant compatibility: The 4G and 5G models share the same battery bay dimensions, connector pinout, and BMS communication protocol. Samsung used one cell platform across both SKUs, so the EB-BN985ABY fits every regional build — Snapdragon and Exynos included.
- Bench tested on actual hardware: We ran this cell on an SM-N985 unit and confirmed the BMS handshake completed within one charge cycle. The protection circuit tripped correctly at voltage floor and ceiling, and the charge IC accepted both standard and fast-charge current levels after the second cycle.
- Fuel gauge recalibration on first cycle: 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 fast charging pushes current into an uncalibrated cell.
Why the Note 20 Ultra reports wrong battery percentage after a cell swap
The Galaxy Note 20 Ultra uses a coulomb counter integrated into the fuel gauge IC to track charge state. When the original cell is replaced, the IC still holds the old cell's charge curve in memory. It maps voltage readings against a curve that no longer matches, producing percentage figures that drift — often optimistic in the mid-range and suddenly dropping near 20%. One full slow charge-discharge cycle rewrites the reference curve. After that cycle, percentage reporting stabilises and the OS reads the new cell accurately.
Sudden shutdown at 20–30% after replacement
This is a voltage cliff issue, not a capacity problem. Under high-draw loads — 5G modem, high-refresh display, or simultaneous GPS — cell voltage drops sharply below the BMS cutoff threshold before the percentage display catches up. It happens most on replacement cells in the first few cycles because the fuel gauge IC has not yet mapped the new cell's voltage-to-capacity curve. Run two full discharge cycles without fast charging and the shutdowns will stop. If the phone still shuts down at 25%, check that cell voltage at that point is above 3.5V with a USB voltage meter on charge — below that indicates a cell fault.