Toshiba IP4100 Cordless Phone Compatible Battery 3.7V 1200mAh

Toshiba IP4100 — 3.7V Li-ion Replacement Battery (10000060 / RTR001F02)

This is a 3.7V, 1200mAh Li-ion replacement battery for the Toshiba IP4100 DECT cordless handset. It slots into the handset's battery compartment and restores talk time and standby functionality when the original cell has degraded. Voltage and physical dimensions match the OEM spec: 53.00 × 34.00 × 5.70mm.

• IP4100 handset fit: The IP4100 runs a single-cell 3.7V Li-ion pack on a low-current DECT radio circuit. This battery uses the same connector pinout and BMS communication profile, so the base station's charge management reads it correctly and does not throw a charge fault.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the IP4100 platform. The BMS held cutoff at 4.2V on charge and tripped low-voltage protection at 3.0V — both within the handset's expected operating window.
• First-charge protocol for DECT Li-ion handsets: After installing, seat the handset in the base and leave it on charge for a full 16 hours before first use. DECT phones arrive from storage at a partial state of charge, and the base station's trickle-charge circuit needs uninterrupted time to bring a fresh cell to rated capacity.

Talk time shorter than expected after fitting the new battery

Li-ion cells in cordless phones are stored for months before sale, which drops them to a partial charge state. The IP4100's charge circuit tops the cell up quickly on first seat, but the battery hasn't yet been through a full charge-discharge cycle. Most users see rated capacity stabilise after three to five complete cycles — charge to full, use until the handset warns low, return to base and repeat.

Toshiba IP4100 base station showing a charge error after battery swap

The IP4100 base station checks incoming battery voltage before committing to a charge cycle. A new cell shipped at storage voltage — typically 3.5V or below — can sit outside the window the base expects to see, triggering an error light instead of starting the charge. Remove the handset, wait 30 seconds, and reseat it firmly so the contacts close cleanly. If the error persists, use a USB charger or compatible external charger to bring the cell above 3.6V first, then return it to the base.