Lenovo ET180 Replacement Battery 3.7V 1500mAh PE2021

Lenovo ET180 — 3.7V Li-ion Replacement Battery (PE2021)

This is a 3.7V, 1500mAh Li-ion battery for the Lenovo ET180 smartphone. It replaces OEM part number PE2021. Fit this cell when the original no longer holds a charge or the device shuts down unexpectedly.

• ET180 platform fit: The ET180 uses a single-cell 3.7V Li-ion configuration with a matching connector and BMS communication line. The replacement cell matches the voltage rail and connector pinout so the charge IC and fuel gauge IC communicate correctly from the first boot.
• Bench tested on actual hardware: We ran full charge and discharge cycles on the ET180 with this cell installed. The BMS accepted the charge handshake without fault codes, and the fuel gauge IC tracked state-of-charge through a complete cycle without dropout.
• First-cycle fuel gauge recalibration: On first use after installation, disable fast charging if available and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the ET180 after a cell swap

The ET180's fuel gauge IC stores a discharge curve calibrated to the original cell. A new cell with slightly different internal impedance hits a voltage cliff at a different state-of-charge than the old curve predicts. The OS reads 25% remaining, but the cell voltage drops below the modem's minimum rail under load and the phone cuts out. One full discharge-to-shutdown followed by a full uninterrupted charge resets the coulomb counter and eliminates the premature cutoff.

ET180 not powering on after the replacement battery sat in storage

Li-ion cells self-discharge during storage. If the cell dropped below 2.5V, the BMS enters lockout mode to prevent damage and will not pass current to the device. Plug into a wall charger — not a USB port — and leave it connected for at least 30 minutes without pressing the power button. The charge IC trickle-charges the cell back above the BMS recovery threshold, typically 2.9V, after which the phone will power on normally.