AP18 Acer Liquid E1 Replacement Battery 3.7V 1650mAh

Acer Liquid E1 / V360 — 3.7V Li-ion Replacement Battery (AP18)

This is a 3.7V, 1650mAh Li-ion replacement battery for the Acer Liquid E1, Liquid E1 Duo, and V360 smartphones. It fits the same physical bay and connector as the original AP18 cell. Capacity listed is from product data: 6.11Wh at 1650mAh.

• Liquid E1, Liquid E1 Duo, and V360 compatibility: All three models share the same battery bay dimensions, voltage rail, and AP18 connector. The BMS handshake requirements are identical across the series, so one cell covers all three variants without modification.
• Bench tested on actual hardware: We ran the AP18 replacement through charge and discharge cycles on the V360 platform. The BMS accepted the cell on the first cycle, the charge IC ramped current correctly, and no thermal cutoff events were triggered during the test sequence.
• Fuel gauge recalibration after swap: On first use after installation, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100%. This gives the fuel gauge IC a full voltage window to map the new cell's discharge curve before the OS starts reporting percentage data it can trust.

Sudden shutdown at 20–30% on the Acer Liquid E1 after a cell swap

This is a voltage cliff problem, not a capacity problem. A new cell's discharge curve differs from the aged curve the fuel gauge IC learned on the original battery. When the phone hits a load spike — modem transmit, screen wake, or a background sync — the cell voltage drops sharply below the cutoff threshold even though the reported percentage still looks safe. The OS never sees the low-voltage event coming and shuts down hard. One full discharge-to-shutdown cycle followed by a complete uninterrupted charge resets the coulomb counter and eliminates most cliff events.

Acer Liquid E1 showing wrong battery percentage after replacement

The fuel gauge IC on this platform stores a learned discharge curve for the original cell. A replacement cell with different internal resistance and capacity characteristics will read incorrectly against that stored curve — often showing 100% after a short charge or dropping suddenly from 40% to single digits. This is not a fault in the replacement cell. Run the phone from full charge down to automatic shutdown without interruption, then charge back to 100% in one session. After that cycle, the gauge recalibrates and percentage reporting stabilises within a few degrees of actual state-of-charge.