About this replacement
Crosscall Core M4 / Core M4 Go — 3.85V Li-Polymer Replacement Battery (COM4BAT100)
This is a 3.85V, 2800mAh Li-Polymer replacement battery for the Crosscall Core M4 and Core M4 Go smartphones. It matches OEM part number COM4BAT100 and slots into the original battery bay without modification. Physical dimensions are 65.90 × 49.50 × 5.40mm.
- Core M4 and Core M4 Go compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell covers both variants without adaptation.
- Bench tested on actual hardware: We ran this cell through a full charge and discharge cycle on a Core M4 unit. The BMS accepted the new cell without fault codes, charge termination triggered correctly at 4.35V, and protection cutoff activated at the expected low-voltage threshold.
- Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging begins on an uncalibrated reference.
Sudden shutdown at 20–30% on the Core M4 after a cell swap
A new cell has a slightly different voltage-versus-capacity curve than the aged original. The fuel gauge IC on the Core M4 still references the old curve, so it misjudges remaining capacity. Under modem transmit or screen-on load, the actual cell voltage drops below the shutdown threshold even while the gauge shows charge remaining. One full discharge-charge cycle at standard rate lets the coulomb counter re-anchor its zero point. After that cycle, sudden shutdowns in the 20–30% range typically stop.
Core M4 not powering on after the battery sat discharged in storage
Li-Polymer cells self-discharge over time. If the cell drops below approximately 2.5V per cell, the BMS enters lockout to prevent damage and blocks normal boot. The Core M4 will show nothing on screen — no charging animation, no vibration. Connect to a wall charger rated at least 5V/1A and leave it for 20–30 minutes without pressing any button; the BMS needs a trickle current to recover before it will allow a full charge or boot sequence. If the screen still shows nothing after that window, check the cable and adapter are delivering voltage at the port before assuming cell failure.