Sony SPP-940 Cordless Phone Replacement Battery 2.4V 1200mAh

Sony SPP-940 / SPP-977 / SPP-A1050 Series — 2.4V Ni-MH Replacement Battery

This is a 2.4V 1200mAh Ni-MH replacement battery for Sony cordless phone handsets including the SPP-940, SPP-977, SPP-A1050, and SPP-A1070. It fits directly into the handset battery compartment and restores portable operation when the original cell no longer holds charge. Voltage and capacity match the stock Sony specification.

• SPP-940 / SPP-977 / SPP-A1050 series compatibility: These handsets share the same 2.4V two-cell Ni-MH format, connector pinout, and charge circuit. A single battery pack services the full group without modification.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on SPP-series handsets. The base station charge circuit accepted the battery without error, and the BMS held within the expected 2.4V nominal range across all test cycles.
• First-charge protocol for Ni-MH cordless packs: After installing, seat the handset in the base and leave it for a full 16 hours before use. Ni-MH cells shipped in storage-discharge state need this slow initial charge to reach rated 1200mAh capacity — skipping it leaves you with noticeably shorter talk time from day one.

Base station charge light staying off after installing a new Ni-MH pack

Sony SPP-series base stations use a delta-V detection circuit to sense when a Ni-MH pack is accepting charge. If the replacement battery arrives at a very low resting voltage from storage, the base may not trigger the charge cycle at all — the indicator stays dark and nothing happens. The fix is to check that the handset is fully and squarely seated in the cradle, then wait up to 20 minutes; the circuit needs a minimum cell voltage to initiate. If it still shows no activity, remove the battery, let it sit at room temperature for 10 minutes, and reseat — a brief recovery from deep storage discharge is usually enough to push the pack above the 2.0V threshold the base needs to start.

Handset losing range or breaking up on calls after battery swap

Range dropouts after a battery replacement usually point to voltage sag under RF transmit load, not a faulty pack. When a fresh Ni-MH cell hasn't been through its conditioning cycles, internal resistance is higher than rated — voltage dips the moment the handset's transmitter fires, and the radio output weakens. Run three to five full charge-and-discharge cycles and internal resistance will fall toward spec. If breakup persists past five cycles, check that the battery contacts in the handset are clean and making firm contact — oxidised pins add resistance and compound the sag problem.