Telecom T306 T-Fax CM301 Replacement Battery 3.6V 400mAh

Telecom T-Fax CM301 / CM310 — 3.6V Ni-MH Replacement Battery (T306)

This is a 3.6V 400mAh Ni-MH replacement battery for the Telecom T-Fax CM301, T-Fax CM310, Colors Memo, and Colors View cordless fax handsets. It replaces OEM part numbers T306, 4M3EMJZ, and F6M3EMX. When the original battery can no longer hold a charge, this unit restores handset operation to its original state.

• T-Fax CM301, CM310, Colors Memo, Colors View compatibility: These models share the same 3.6V single-cell Ni-MH chemistry, connector pinout, and physical envelope — 48.30 × 33.41 × 6.65mm — so one battery covers all four handsets without modification.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on the CM301 handset. The BMS accepted the charge handshake from the base station correctly, and voltage held steady across the RF transmit bursts during a call simulation.
• First-charge protocol for Ni-MH cordless handsets: After installing, seat the handset in the base cradle for a full 16 hours before first use. Ni-MH cells in cordless phones ship at reduced capacity and need a slow, uninterrupted initial charge cycle to reach the rated 400mAh.

Why the T-Fax CM301 handset loses range after a battery swap

DECT handsets boost RF transmit power in short bursts. A freshly installed Ni-MH pack that hasn't completed its first full charge cycle has lower usable capacity, and internal resistance is higher until the cells are conditioned. Under the brief high-current draw of a DECT transmit burst, voltage sags — the handset drops to a lower power mode or cuts the RF link entirely. Running three to five full charge-discharge cycles brings cell resistance down and eliminates the sag.

Base station shows no charge or error light on new Ni-MH pack

Cordless phone base stations check incoming battery voltage before committing to a charge cycle. A Ni-MH pack stored at low state of charge can sit below the 3.3V threshold the base expects to see, causing it to signal an error or show no charge activity at all. The fix is to place the handset in the cradle and leave it for at least 30 minutes — the base will trickle charge until voltage climbs above the acceptance threshold, then switch to normal charge mode. If the light still shows an error after 30 minutes, remove and re-seat the handset to trigger a fresh detection cycle.