Sanyo 23621 Cordless Phone Compatible Battery 3.6V 1300mAh

Sanyo 23621 / CL-410 Series — 3.6V Ni-MH 1300mAh Replacement Battery

This is a 3.6V, 1300mAh Ni-MH replacement battery for Sanyo cordless phones including the 23621, CL-410, 3N-600AA(mtm), and GES-PCF02 among others. It slots into the handset where the original pack sits and restores the phone to working condition. Capacity is 1300mAh — 4.68Wh total energy.

• Handset compatibility across the range: These Sanyo models share the same 3.6V three-cell NiMH pack format and connector pinout. The base station charges at the same voltage rail across all of them, so one battery covers the full group without modification.
• Bench tested on actual hardware: We cycled this pack through the base station charge circuit and confirmed the BMS accepted the charge handshake at the correct voltage. Charge termination triggered cleanly — no false cutoffs or error lights on the base unit.
• First-charge protocol for NiMH cordless packs: After installing, seat the handset in the base and leave it untouched for a full 16 hours before first use. NiMH cells in cordless phones need a slow initial charge to reach rated capacity — a quick top-up off the shelf will not get you there.

Why the base station shows an error light with a new NiMH pack

NiMH batteries lose voltage during storage. If the pack sits in a warehouse for weeks, its open-circuit voltage can drop below the threshold the Sanyo base station expects before it begins a charge cycle. The base interprets this as a fault rather than a discharged battery. To clear it, remove the battery, hold the handset power button for five seconds to drain any residual charge from the handset capacitors, reinsert the battery, and place it straight back on the base — most units will then accept the pack and begin charging normally.

Talk time shorter than the original battery after replacement

This is expected behaviour with fresh NiMH cells — it is not a fault with the battery. NiMH chemistry requires three to five full charge and discharge cycles before the cells reach their rated 1300mAh capacity. Each cycle, talk time will noticeably improve. Run the handset down until it signals low battery, return it to the base for a full charge, and repeat — by cycle four or five, capacity should be at or very close to the rated figure.