Cricket Ascend Q M660 Replacement Battery 3.7V 1500mAh

Cricket Ascend Q / M660 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1500mAh Li-ion battery for the Cricket Ascend Q and M660 smartphones. It slots into the same bay as the original cell and connects to the same charge IC and fuel gauge circuit. Capacity matches the factory spec at 5.55Wh.

• Ascend Q and M660 platform: Both the Ascend Q and M660 share the same battery bay dimensions, connector pinout, and charge IC handshake. A single cell covers both devices without modification.
• Bench tested on actual hardware: We ran the cell through charge and discharge cycles on the Ascend Q platform. The BMS accepted the charge IC handshake on the first cycle and held voltage within the expected 3.6–4.2V window throughout.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge to auto-shutdown and charge back to 100% before enabling any fast charge mode. The Ascend Q's fuel gauge IC is calibrated to the old cell's discharge curve — one full cycle resets it against the new cell so percentage readings stay accurate.

Why the Ascend Q reports wrong battery percentage after a cell swap

The Ascend Q uses a coulomb-counting fuel gauge IC that tracks charge by measuring current in and out of the cell over time. When the original cell degrades, the gauge recalibrates its empty-point estimate downward to match the worn cell. A new cell with full capacity throws off that reference, so the phone reads 0% long before the cell is actually depleted. One full discharge-to-shutdown followed by a complete charge resets the gauge's empty and full endpoints against the new cell's actual voltage curve. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the Ascend Q

This happens when the fuel gauge IC hasn't yet mapped the new cell's discharge curve accurately. At 20–30% indicated, the phone requests a burst of current for the modem or display — the uncalibrated gauge underestimates available voltage, the protection circuit sees an apparent sag, and the device cuts off. This isn't a faulty cell. Run the phone down to auto-shutdown once, charge fully to 4.2V, and the gauge recalibrates. Shutdowns at partial charge stop after that first complete cycle.