EB664239HA Samsung Caliber R850 Replacement Battery 3.7V 800mAh

USCellular Caliber R850 — 3.7V Li-ion Replacement Battery (EB664239HA)

This is a 3.7V, 800mAh Li-ion replacement battery for the Samsung Caliber R850 (SCH-R850). It fits USCellular variants including SCHR850BLKUSC and SCHR850ZKAUSC. Capacity matches the original OEM specification at 2.96Wh.

• Caliber R850 variant compatibility: The SCH-R850 platform shares one battery footprint and connector pinout across all USCellular retail variants. The BMS handshake protocol is identical across SCHR850BLKUSC and SCHR850ZKAUSC, so one cell fits all listed model numbers without firmware or connector conflict.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on an SCH-R850 unit. The BMS accepted charge from the onboard charge IC without triggering overvoltage cutoff, and the phone exited low-battery lockout cleanly at the standard recovery threshold.
• Fuel gauge recalibration on first install: After fitting this cell, disable any fast-charge accessory and run one complete discharge-to-charge cycle. The Caliber R850 fuel gauge IC is calibrated against the old cell's discharge curve — a full cycle lets it map the new cell's characteristics before reporting accurate percentages.

Sudden shutdown at 20–30% on the Caliber R850 after a cell swap

This is a voltage cliff failure, not a capacity problem. When the phone's modem fires or the screen refreshes at high brightness, current draw spikes sharply. A new cell with an uncalibrated fuel gauge reports 25% remaining, but the actual resting voltage dips below the 3.4V cutoff threshold under that load. The phone interprets this as a hard undervoltage event and shuts down to protect the cell. One full discharge-charge cycle lets the coulomb counter recalibrate, and the shutdowns stop.

Phone will not power on after the replacement cell sat in storage

Li-ion cells self-discharge in storage. If this battery has been stored for several months, its resting voltage may have dropped below 2.5V per cell — the threshold where the BMS latches into deep-discharge lockout and blocks all charge current to prevent plating damage. The Caliber R850 will show no charge indicator and will not boot. Connect to the OEM wall adapter rather than a PC USB port, which may not supply enough current to trigger the BMS recovery ramp. Hold on charge for 20–30 minutes before attempting to power on; the BMS should release lockout once the cell climbs above 2.9V.