AudioVox BTR1400 Replacement Battery 3.7V 600mAh

AudioVox CDM-1400 / PCS-1400 Series — 3.7V Li-ion Replacement Battery (BTR1400)

This is a 3.7V, 600mAh Li-ion replacement battery for the AudioVox CDM-1400, PCS-1400, PPC-1400, and PPC-1400 Slice. It slots into these early-2000s flip phones when the original cell has degraded past usable capacity. OEM part numbers BTR1400 and BTR-1400 both apply to this cell.

• CDM-1400 and PCS-1400 platform fit: These models share the same physical footprint, connector pin-out, and 3.7V single-cell voltage rail. One cell covers the entire group without modification.
• Bench tested on actual hardware: We cycled this cell through the CDM-1400 charge circuit and confirmed the BMS accepts charge current normally, holds voltage at load, and trips protection at the correct low-voltage cutoff without false shutdowns.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge down to auto-shutoff before recharging. The CDM-1400 has no active coulomb counter — it reads voltage-curve estimates. One complete cycle anchors the gauge to the new cell's actual discharge curve so percentage readings stabilise.

Sudden shutdown at 20–25% on the CDM-1400 after cell swap

The CDM-1400's fuel gauge estimates remaining charge from a stored voltage-to-capacity curve calibrated to the original cell. A fresh Li-ion cell has a steeper voltage cliff below 3.6V than a worn one. When the phone's transmit circuit draws current during a call, voltage briefly sags below the BMS cutoff threshold even though the displayed percentage still reads 20–25%. The fix is one full discharge-charge cycle — after that, the gauge recalibrates and shutdowns at low percentage stop.

Phone won't power on after the battery has been sitting in storage

Li-ion cells self-discharge at roughly 2–3% per month. A CDM-1400 battery stored for a year or more can drop below 2.5V per cell, which triggers BMS lockout — the protection circuit disconnects the cell entirely to prevent damage. The phone sees no voltage at the connector and won't respond to the power button. Connect the phone to a charger and leave it for 15–20 minutes before pressing power — most chargers trickle a recovery current that brings the cell above the 2.5V re-enable threshold before the BMS unlocks.