Telefunken CS4 Replacement Battery 4.8V 1500mAh Ni-MH

Telefunken CS4 / CS5 / CS6 / CA6 Series — 4.8V Ni-MH Replacement Battery

This 4.8V 1500mAh Ni-MH battery replaces the original handset battery in Telefunken CS4, CS5, CS6, and CA6 cordless DECT phones. It restores full handset operation without replacing the entire phone. Voltage and cell count match the original pack exactly.

• CS4, CS5, CS6, CA6 compatibility: These Telefunken handsets share the same 4.8V four-cell NiMH pack format, connector pinout, and physical envelope. The same battery fits across this range because Telefunken built the CS and CA series on a common handset platform.
• Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on DECT handset hardware. The BMS accepted charge correctly from the base station cradle, and the cells balanced without heat anomalies across multiple cycles.
• First charge after installation: After fitting, seat the handset in the base and leave it for a full 16 hours before use. NiMH cells arriving from storage are partially discharged — a slow initial charge lets each cell reach rated capacity rather than the partial fill a standard charge cycle delivers.

Talk time shorter than the original battery after replacement

NiMH cells need three to five full charge and discharge cycles before they deliver rated capacity. A new pack straight from storage has suppressed capacity — this is a chemistry characteristic, not a fault. Each complete cycle conditions the cells and recovers usable capacity incrementally. By cycle five, the pack should be performing at or close to the rated 1500mAh.

Base station charge light not activating with new battery installed

NiMH packs can drop to very low voltages during storage. Some Telefunken base stations will not initiate a charge cycle if the incoming voltage sits below the acceptance threshold — typically around 3.6V for a four-cell pack. The base interprets a deeply discharged pack as an absent or faulty battery. To recover it, briefly charge the pack directly at a low current using an external NiMH charger until voltage reaches approximately 4.0V, then return the handset to the base.