GP 55AAAHR28MX Cordless Phone Replacement Battery 2.4V 650mAh

GP 55AAAHR28MX — 2.4V Ni-MH Replacement Battery

This GP 2.4V 650mAh Ni-MH battery replaces the OEM pack in cordless DECT phones using the 55AAAHR28MX or T382 part number. It fits handsets that use a slim twin-cell Ni-MH pack charged via a base station or cradle. Swap it in when your handset no longer holds a charge or the original pack has swollen or failed.

• Twin-cell 2.4V Ni-MH pack format: Cordless phones in this category run a 2.4V rail from two AA-sized Ni-MH cells in series. The base station charges at a trickle rate matched to this chemistry — a Li-ion or Ni-Cd pack at the same voltage will not cycle correctly through the same dock.
• Bench tested on actual hardware: We cycled this pack through a DECT base station dock and confirmed the charge acceptance threshold was met from a rested state. The BMS in the base detected the pack within the expected voltage window and began the trickle charge sequence without fault.
• First-charge conditioning on DECT handsets: After installing, seat the handset in the base for a full 16-hour charge before first use. Ni-MH cordless phone packs ship at partial charge and need a slow first cycle to reach rated capacity. Skipping this step will make the first few sessions shorter than expected.

Talk time shorter than rated after battery swap

Ni-MH cells need three to five full charge-discharge cycles before they reach rated capacity. A freshly installed pack will often deliver noticeably shorter talk time on the first few uses — this is normal electrochemical behaviour, not a fault. Each cycle builds up the crystalline structure inside the cell that stores charge. After five cycles from a full 16-hour base charge, capacity should stabilise at or near the rated 650mAh.

Base station shows no charge or error light after fitting new pack

Ni-MH packs self-discharge during storage, and a deeply discharged pack can sit below the base station's charge-acceptance threshold — typically around 2.0V for a 2.4V pack. The base reads the voltage on contact, and if it is too low, the charge circuit may not trigger. Leave the handset seated in the base for at least 30 minutes without removing it; many DECT bases have a recovery trickle mode that kicks in below the main threshold. If the indicator still shows an error after 30 minutes, check the contact pins on both the handset and the base for corrosion and clean with a dry cloth.