OpenStage SL4 Cordless Phone Compatible Battery 3.7V 830mAh

OpenStage SL4 / SL5 / SL6 — 3.7V Li-ion Replacement Battery

This 3.7V 830mAh lithium-ion battery fits the OpenStage SL4, SL5, and SL6 cordless DECT handsets. It replaces the original cell when the handset no longer holds a charge or stops powering on. Capacity is 830mAh (3.07Wh) — matching the stock specification.

• SL4, SL5, and SL6 compatibility: These three handset models share the same battery bay dimensions, connector pinout, and 3.7V supply rail — one cell fits all three without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SL4 platform. The protection circuit cut in correctly at low voltage and the base station accepted the charge handshake without error.
• First charge after installation: Place the handset in the base immediately after fitting the new cell and leave it there for a full 16 hours before use. Li-ion cells that have sat in storage ship at a reduced state of charge — a complete first cycle brings the cell to rated capacity.

Talk time shorter than expected after battery replacement

A new Li-ion cell ships partially discharged after storage. If you start using the handset before it completes a full charge, the first few cycles will feel short. Run two or three full charge-to-discharge cycles and talk time will stabilise at the rated capacity. If it stays short after three full cycles, check that the handset contacts are clean and making firm contact with the base cradle.

Handset not pairing with base after battery swap

Removing the battery completely cuts power to the handset, and some DECT phones lose their pairing data when the cell drops out. The fix is to re-register the handset from the base station menu — on most OpenStage systems this is under Settings → Registration. You will need the system PIN, which defaults to 0000 on most units. Once registered, the handset reconnects immediately.