Sanyo 36-A Cordless Phone Compatible Battery 3.6V 400mAh

Sanyo 36-A / CLT Series — 3.6V Ni-MH Replacement Battery (4M3EMJZ)

This is a 3.6V, 400mAh Ni-MH replacement battery for Sanyo cordless phone handsets. It fits the 36-A, CLT35, CLT36, CLT39, and related models. Same voltage, same footprint, same connector orientation as the factory pack.

• CLT and 36-A handset compatibility: These models share a common 3.6V single-cell NiMH rail with the same physical connector and BMS handshake requirements. The base station charges at a fixed trickle rate, so any pack installed must match the 3.6V nominal — a mismatch here stops charging entirely.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a CLT-series handset. The base station accepted the pack without fault, the charging LED lit within 30 seconds of docking, and voltage held above 3.4V through the full discharge curve.
• First charge after installation: After fitting this pack, place the handset in the base and leave it for a full 16 hours before use. NiMH cells in cordless handsets need a slow first charge to align all cells and reach rated capacity — pulling it early on the first cycle shortens the long-term result.

Why the CLT handset loses range after a battery swap

DECT transmitters in these handsets draw a short high-current pulse every 10ms to maintain the radio link. A fresh NiMH pack with low charge or an unconditioned cell has higher internal resistance than a settled pack, so voltage sags under that RF pulse. The handset's transmit power drops when voltage sags, and range shrinks noticeably before the battery shows any other sign of weakness. Running two or three full charge-discharge cycles conditions the cells and lowers internal resistance — range returns once the pack is properly cycled.

Base station shows no charge light after installing the new pack

NiMH batteries self-discharge during storage — by the time this pack ships and is installed, the resting voltage may be below the threshold the base station uses to confirm a valid battery is present. Some Sanyo base stations will not begin charging if the pack voltage reads below roughly 3.0V. Remove the handset, wait 10 seconds, and re-dock it firmly — the base often retries its detection cycle on re-insertion. If the charge light still does not appear, short-circuit the contacts briefly with a resistive load to bring the cell voltage up slightly, then re-dock.