Southwestern Bell S60508 Cordless Phone Replacement Battery 3.6V

Southwestern Bell S60508 — 3.6V Ni-MH Replacement Battery

This 3.6V 600mAh Ni-MH battery replaces the handset battery in the Southwestern Bell S60508 cordless phone. It restores talk and standby capacity to the handset after the original cell degrades. Dimensions are 42.64 x 30.00 x 14.45mm — confirm these against your existing pack before installing.

• S60508 handset compatibility: The S60508 handset runs on a single 3-cell Ni-MH pack at 3.6V. This battery matches that voltage rail and the physical footprint of the original, so the handset cover closes and the charging contacts align with the base cradle correctly.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a Ni-MH-compatible test rig. The BMS held voltage within spec across repeated cycles, and the cell temperature stayed within safe limits during fast-charge simulation.
• First-charge protocol for Ni-MH handsets: After installing, seat the handset in the base and leave it for a full 16 hours before making any calls. Ni-MH cells in cordless phones need this slow initial charge to reach rated capacity — cutting it short is the single biggest reason a new battery underperforms from day one.

Base station showing charging error on a new Ni-MH pack

A freshly shipped Ni-MH battery can arrive with a resting voltage below 3.0V after months in storage. Some S60508 base stations use a delta-V detection circuit to confirm a valid battery is seated — if the voltage is too low, the base reads it as a fault rather than a discharged cell. The fix is to leave the handset in the base undisturbed for at least two hours before expecting the charge indicator to show normal. Most bases will accept the pack once it has trickle-charged back above roughly 3.2V.

Talk time shorter than the original battery after replacement

Ni-MH cells do not deliver full rated capacity on the first few cycles — this is normal chemistry, not a defective unit. The electrodes need three to five full charge-discharge cycles before the cell reaches its 600mAh rating. Run the handset down until it signals low battery, then return it to the base for a complete charge each time. By cycle four or five, talk time should match or exceed what the original pack delivered when it was new.