Swisscom TOP S317 Cordless Phone Replacement Battery 3.6V 500mAh

Swisscom TOP S317 — 3.6V Ni-MH Replacement Battery

This 3.6V, 500mAh Ni-MH battery replaces the original pack in the Swisscom TOP S317 cordless DECT handset. It restores power to the handset so it operates wirelessly from the base station. Capacity figure is taken directly from product data: 500mAh (1.8Wh).

• TOP S317 handset fit: The S317 uses a compact single-cell NiMH pack at 3.6V to run the DECT radio, keypad, and display. This battery matches that voltage rail and physical footprint — 53.60 × 36.95 × 7.95mm — so the compartment lid closes flush and the contacts seat correctly.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on the S317 platform. The battery accepted charge from the base station cradle without triggering an error state, and the BMS held voltage within the range the handset's RF circuit expects under transmit load.
• First-charge protocol for NiMH cordless packs: After installing, place the handset in the base station and leave it for a full 16 hours before first use. NiMH cells in cordless phones need that slow initial charge to reach rated capacity — a shorter first charge will leave the pack performing below 500mAh for its first several 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 hit rated capacity. On the first cycle, the S317 handset may cut out earlier than expected — this is normal cell behaviour, not a fault with the battery. Each subsequent full cycle conditions the cell and recovers more capacity. By cycle five, the pack should be performing at or close to 500mAh.

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

A NiMH pack that has sat in storage drops to a low resting voltage — sometimes below the threshold the S317 base station uses to confirm a valid battery is present before it starts charging. The base reads that low voltage as an absent or faulty cell and shows an error or no charge indicator. To recover it, remove the handset, wait 30 seconds, reseat it firmly, and check the contacts are clean. If the error persists, the pack voltage may need a brief trickle from an external NiMH charger at 0.05C to bring it above the base acceptance threshold of approximately 3.0V before normal cradle charging resumes.