Archos F18 Replacement Battery 3.7V 1000mAh ACF18

Archos F18 — 3.7V Li-ion Replacement Battery (ACF18)

This is a 3.7V, 1000mAh Li-ion replacement cell for the Archos F18 smartphone. It fits the F18 directly and restores power when the original cell can no longer hold a usable charge. OEM part numbers ACF18 and ACF18V2 both apply to this unit.

• F18 fit: The Archos F18 uses a compact 61.00 × 38.15 × 4.58mm cell at 3.7V. This replacement matches that footprint and voltage rail exactly, so the phone's charge IC and BMS handshake proceed without error codes or charge refusal.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the F18 platform. The BMS accepted the cell without flagging an incompatible cell event, and the charge IC stepped through trickle, bulk, and termination phases normally.
• Fuel gauge recalibration on first cycle: After swapping the cell, disable any fast-charge mode and run one complete discharge down to auto-shutoff, then charge uninterrupted to 100%. The F18's fuel gauge IC needs that full cycle to map the new cell's discharge curve — skipping it causes the percentage readout to jump or stall mid-charge.

Why the F18 reports wrong battery percentage after a cell swap

The F18 uses a fuel gauge IC that stores a learned discharge curve from the original cell. When you install a new cell, that stored curve no longer matches the actual chemistry profile. The IC keeps reading voltage against the old curve, so it reports inaccurate percentages — sometimes showing 80% when the phone is minutes from shutoff. One full uninterrupted discharge-charge cycle forces the IC to rewrite its internal state of charge map against the new cell. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under load — screen backlight, cellular radio, and audio can combine to pull the cell below the BMS cutoff threshold while the fuel gauge still reads 20–30%. A fresh Li-ion cell has a steeper voltage cliff at low state of charge until it has been cycled a few times. The fuel gauge IC hasn't yet learned where that cliff sits on the new cell, so it doesn't warn the OS in time. Run two to three full discharge-charge cycles and the shutdowns will move to 5% or below as the IC recalibrates its low-voltage prediction to 3.4V cutoff.