AudioVox BTR1100 CDM-1100 Replacement Battery 3.7V 1500mAh

AudioVox CDM-1100 / CDM-130 — 3.7V Li-ion Replacement Battery (BTR1100)

This is a 3.7V, 1500mAh Li-ion replacement cell for the AudioVox CDM-1100 and CDM-130 flip phones. It slots directly into the original battery compartment and restores power to devices where the factory cell has lost capacity or no longer holds a charge. Voltage and connector match the original BTR1100 specification.

• CDM-1100 and CDM-130 compatibility: Both models share the same battery bay geometry, 3.7V nominal rail, and BTR1100 connector pinout. One cell fits both without modification.
• Bench tested on actual hardware: We cycled the cell through a full discharge and charge sequence on the CDM-1100. The BMS accepted charge from the handset's internal charge IC without fault, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge down to automatic shutoff before recharging to full. The CDM-1100 does not use a coulomb counter — its fuel gauge estimates state of charge from a fixed voltage-curve lookup, which was calibrated to the original aged cell. A single full cycle re-anchors the curve to the new cell's actual voltage profile.

Why the CDM-1100 shows wrong battery percentage after a cell swap

The CDM-1100 estimates charge level by mapping open-circuit voltage to a stored discharge curve. That curve was set against the original BTR1100 cell, which had degraded capacity and a flatter voltage profile. A new cell with full capacity holds a higher voltage at every state of charge. The handset reads that higher voltage as an inflated percentage, then drops suddenly when the new cell's curve diverges from the stored one. One full discharge-charge cycle corrects the mismatch.

Sudden shutdown at 20–25% on the CDM-1100

This happens when the cell voltage sags below the BMS cutoff threshold under transmit load before the displayed percentage reaches zero. On a legacy flip phone, the radio transmitter draws a short burst of current during a call or SMS send — enough to pull cell voltage down sharply if the fuel gauge has not been calibrated to the new cell. The phone reads a safe percentage, then the BMS trips on actual terminal voltage and cuts power. Run one full discharge cycle from 100% to automatic shutoff, then recharge fully; this resets the voltage-to-percentage mapping and the shutoff should move below 5%.