Swisscom Top S329 Replacement Battery 2.4V 500mAh Ni-MH

Swisscom Top S329 / Aton CL-102 — 2.4V Ni-MH Replacement Battery

This is a 2.4V, 500mAh Ni-MH rechargeable battery for the Swisscom Top S329 and Aton CL-102 cordless phones. It slots directly into the handset and restores power to a unit that no longer holds a charge. Dimensions are 35.60 × 31.80 × 6.60mm — confirm these against your existing pack before ordering.

• Top S329 and Aton CL-102 compatibility: Both handsets run a single-cell 2.4V Ni-MH configuration with the same form factor and connector orientation. One pack covers both models without modification.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a DECT handset test rig. The BMS accepted charge from a standard base station cradle without triggering a fault state, and the cell voltage climbed steadily to full charge over 14 hours.
• First-charge protocol for NiMH cordless packs: After installing, seat the handset in the base and leave it for a full 16 hours before first use. NiMH cells in DECT phones need a slow initial charge to reach rated capacity — skipping this step typically cuts usable talk time on early cycles.

Talk time shorter than the original battery after replacement

NiMH cells ship in a partially discharged state and need three to five full charge-discharge cycles before they reach rated capacity. On cycle one, usable talk time may be noticeably lower than expected — this is normal cell behaviour, not a fault. Run the handset until the low-battery indicator appears, return it to the base for a full overnight charge, and repeat. By cycle four or five, capacity stabilises at the rated 500mAh.

Base station showing no charge or error light after fitting new pack

A new NiMH pack that has been in storage can sit below the voltage threshold the base station uses to confirm a valid battery is present. The base reads this as a fault rather than beginning a charge cycle. Remove the handset, leave it off the base for 30 seconds, then reseat it firmly. If the error persists, check the handset contacts with a multimeter — a resting cell voltage below 1.8V on a fresh pack indicates a storage issue, and the cell may need a trickle pre-charge to recover.