ELF0160 NTT DoCoMo FOMA HT1100 Replacement Battery 3.7V 1100mAh

NTT DoCoMo FOMA HT1100 — 3.7V Li-ion Replacement Battery (ELF0160)

This is a 3.7V, 1100mAh Li-ion cell built to fit the NTT DoCoMo FOMA HT1100 handset. It replaces the original ELF0160 battery, which degrades over time on aging Japanese 3G devices. Dimensions are 51.53 × 37.36 × 5.35mm — same physical footprint as the factory cell.

• FOMA HT1100 fit: The HT1100 uses a single-cell 3.7V pack with a three-pin connector carrying charge, ground, and thermistor lines. This replacement matches that pinout and physical latch geometry so the battery seats and communicates correctly with the handset's charge IC.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench, confirmed BMS handshake with the charge controller, and verified the protection circuit trips correctly at low-voltage cutoff before the cell reaches a damaging depth of discharge.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge down to automatic shutoff, then charge uninterrupted to 100% before normal use. The HT1100's fuel gauge IC was calibrated to the old cell's discharge curve — skipping this step leaves the coulomb counter reading against stale reference data.

Why the FOMA HT1100 reports wrong battery percentage after a cell swap

The HT1100 stores discharge-curve data in the fuel gauge IC over hundreds of charge cycles. When a new cell goes in, that stored curve no longer matches the actual cell chemistry. The gauge reads voltage against the old model and calculates percentage incorrectly — often showing 100% that drops fast, or stalling near full. One full discharge-to-shutoff followed by a complete uninterrupted charge resets the reference point and brings percentage readings back in line.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage sags under load — screen backlight, radio transmit, or processor burst — faster than the fuel gauge IC predicted. The HT1100's modem draws a short current spike during a 3G handshake, and if the cell's internal impedance is higher than expected, voltage drops briefly below the protection threshold and the BMS cuts output. Let the phone complete two full discharge-charge cycles first. If shutdowns persist after calibration, check that the battery connector pins are fully seated — a high-resistance contact at the three-pin interface amplifies voltage sag under the same load.