Southwestern Bell FF-1187 Replacement Battery 3.6V 1500mAh

Southwestern Bell FF-1187 / FF-1188 Series — 3.6V Ni-MH Replacement Battery (3SNAA60SX2)

This is a 3.6V, 1500mAh Ni-MH rechargeable battery for Southwestern Bell cordless phone handsets. It fits the FF-1187, FF-1188, FF-1710B, FF-2128, and over 30 additional models in the same family. OEM part numbers covered include 3SNAA60SX2, BP-36MLX600, and 3N600AAL.

• FF-1187 and FF-1188 series compatibility: These models share a 3.6V three-cell NiMH pack format with the same connector footprint and BMS voltage window. A single battery covers the full range without modification.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on the FF-1187 platform. The BMS accepted charge from the base station at the first attempt, with no error state triggered during the conditioning cycle.
• First-charge protocol for NiMH cordless handsets: After installing, seat the handset in the base for a full 16-hour charge before first use. NiMH cells in cordless phones need a slow initial charge to reach rated capacity — skipping this step leaves cells partially formed and talk time below spec for the first several uses.

Base station showing no charge or error light on a new NiMH pack

NiMH batteries can self-discharge to very low voltages during storage and shipping. Some Southwestern Bell base stations check pack voltage before initiating charge and will refuse to charge a pack that reads below their acceptance threshold — typically around 3.0V for a 3.6V three-cell pack. If the charge indicator stays dark or shows an error, remove the handset, wait 30 seconds, then reseat it firmly. If the base still does not respond, the pack voltage may be too low for the base to detect — try a brief trickle from a compatible external NiMH charger set to 100mA to bring it above the acceptance floor before returning it to the base.

Range drops noticeably when the handset moves away from the base

DECT handsets regulate transmit power, and that power draw spikes when the handset is at the edge of range. A NiMH pack with low state of charge sags in voltage under the RF transmit load, which can cause the radio to reduce output or drop the link entirely. This is distinct from a faulty battery — it happens even with a new pack if the first charge cycle was cut short. Run two full 16-hour charge cycles in the base, then retest range. If voltage sag persists after conditioning, check that the pack resting voltage reads at or above 3.6V before the handset leaves the base.