Samsung EB664239HA Replacement Battery 3.7V 800mAh

Samsung SCH-R850 / Caliber R860 — 3.7V Li-ion Replacement Battery (EB664239HA)

This is a 3.7V, 800mAh Li-ion cell built to fit the Samsung SCH-R850, Caliber R850, Caliber R860, and Suede R710 flip phones. It replaces OEM part EB664239HA and drops into the same battery bay without modification. Capacity is rated at 800mAh — matching the original cell specification.

• SCH-R850 / Caliber / Suede platform fit: These models share the same battery footprint, connector pinout, and BMS handshake protocol across the EB664239HA family. The 41.23 × 38.64 × 6.33mm cell fits each variant without case interference or connector force-fitting.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SCH-R850 platform. The BMS accepted the cell without triggering charge-fault states, and voltage held stable at 3.7V nominal across the full discharge curve.
• Fuel gauge recalibration after swap: After installing this cell, run one complete discharge-to-charge cycle before relying on the battery percentage indicator. The SCH-R850's fuel gauge IC was calibrated to the old cell's discharge curve — one full cycle resets that reference so the reported percentage tracks correctly against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff problem, not a capacity defect. When the SCH-R850 makes a call or lights the display, current draw spikes. If the fuel gauge IC is still calibrated to the old cell's discharge curve, it reads 25% remaining while the actual cell voltage has already dropped below the BMS low-voltage cutoff threshold — around 3.0V under load. The phone cuts power before the percentage hits zero. One full discharge-to-charge cycle corrects the fuel gauge reference and eliminates most of these shutdowns. If it persists after two full cycles, check that the battery connector pins are fully seated.

Phone warm near the battery during the first few charges

A new Li-ion cell has slightly higher internal impedance than a broken-in cell. During the first one or two charges, the charge IC pushes current into that higher-impedance cell, and some of that energy converts to heat rather than charge. This is normal and typically resolves by the third cycle as internal impedance drops. If the phone stays noticeably warm beyond the third full charge, verify the charger output — the SCH-R850 should be charged at 5V standard USB, not higher-voltage adapters.