Phone Mate PM2400 Cordless Phone Replacement Battery 3.6V 700mAh

Phone Mate PM2400 / PM5800 Series — 3.6V Ni-MH Replacement Battery

This is a 3.6V, 700mAh Ni-MH replacement battery for Phone Mate cordless handsets. It fits the PM2400, PM2420, PM5800, and PM5820 models. Same voltage, same cell format, same connector orientation as the original pack.

• PM2400 / PM2420 / PM5800 / PM5820 compatibility: These four handsets share the same battery bay dimensions, 3.6V rail, and charging contact layout. One battery covers the full group — no adapter or wiring change needed.
• Bench tested on actual hardware: We cycled this pack on a PM5800 handset. The base station accepted charge on the first seating, the BMS held the 3.6V rail steady under RF transmit load, and capacity stabilised after five full charge–discharge cycles.
• First charge on NiMH cordless packs: After installing, seat the handset in the base and leave it for a full 16 hours before first use. NiMH cells in cordless phone packs need a slow initial charge to activate all cells evenly and reach rated capacity — skipping this shortens the usable charge per cycle from the start.

Range dropping mid-call after a new NiMH pack

DECT handsets ramp up transmit power when signal weakens. That RF load draws current in sharp bursts. A NiMH pack that hasn't completed its conditioning cycles has higher internal resistance, which causes voltage to sag under those bursts. The handset interprets the sag as a low-battery condition and reduces transmit power, cutting range. Run three to five full charge–discharge cycles and the internal resistance drops — the voltage sag shrinks and range recovers.

Base station charge light not coming on after battery swap

New NiMH packs ship in a partially discharged state. Some Phone Mate bases use a voltage threshold to detect a valid battery before starting the charge cycle — if the resting voltage reads too low from storage, the base won't initiate charging. Remove the handset, wait 10 seconds, and reseat it firmly so both charging contacts are flush. If the light still doesn't activate, check the contacts on the handset battery door for debris and confirm the resting pack voltage is above 3.0V before reseating.