Siemens optiPoint W1 Replacement Battery 3.6V 1100mAh Ni-MH

Siemens optiPoint W1 — 3.6V Ni-MH Replacement Battery

This 3.6V, 1100mAh Ni-MH battery replaces the rechargeable pack in the Siemens optiPoint W1 cordless DECT handset. It restores full wireless operation when the original cell has degraded and no longer holds a charge. Dimensions are 58.12 x 45.30 x 15.60mm — confirm these against your existing pack before installing.

• optiPoint W1 handset fit: The optiPoint W1 uses a fixed 3.6V three-cell NiMH configuration tied to the handset's charge circuit. The base station charges at a rate tuned to that chemistry and voltage window, so the cell count and nominal voltage must match exactly.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a DECT handset charge circuit. The BMS accepted the cell without triggering an error state, and voltage remained within the expected 3.6V nominal band across all test cycles.
• First-charge protocol for NiMH handsets: Place the handset in the base immediately after installing the new pack and leave it for a full 16 hours before first use. NiMH cordless phone batteries do not reach rated capacity on a short charge — they need a slow, uninterrupted first cycle to condition properly.

Base station showing a charging error on a new NiMH pack

A freshly shipped NiMH cell sits in storage for weeks or months and its resting voltage drops below the threshold the optiPoint base station expects to see before it begins charging. When the base reads a voltage that low, it flags an error rather than starting the charge cycle. The fix is to place the handset in the base and leave it — most optiPoint base stations will retry the charge acceptance check after a short wait and begin trickle charging once the cell responds. If the error persists past 30 minutes, remove and reseat the handset to trigger another acceptance check.

Talk time shorter than original battery after replacement

NiMH cells ship in a partially discharged state and do not deliver full rated capacity until they have been through three to five full charge and discharge cycles. If call time feels short in the first few days, that is the expected break-in behaviour — not a faulty cell. Run the handset until the low-battery indicator appears, return it to the base for a full charge, and repeat this three to five times. After conditioning, the pack should reach its rated 1100mAh capacity.