Panasonic KX-TG4500 Replacement Battery HHR-P516 6V 1500mAh

Panasonic KX-TG4500 Series — 6V Ni-MH Replacement Battery (HHR-P516)

This is a 6V 1500mAh Ni-MH replacement battery for the Panasonic KX-TG4500 and KXTG4500B cordless phone handsets. It replaces OEM part numbers HHR-P516, HHR-P516A, and HHR-P516A-1H. When the original pack degrades and the handset no longer holds charge, this swap restores full cordless operation.

• KX-TG4500 and KXTG4500B handsets: Both models run the same 6V NiMH cell stack with an identical connector and physical footprint. The base station charges at the same slow-trickle rate for either variant, so one part number covers both without modification.
• Bench tested on actual hardware: We cycled this pack through full charge and discharge on the KX-TG4500 base station. The BMS accepted the NiMH voltage curve without triggering a charge fault, and cell temperature stayed within spec through the full charge window.
• First-charge conditioning on NiMH cordless packs: 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 leaves the pack underperforming for several cycles.

Talk time shorter than expected after the first few charges

NiMH cells leave storage in a partially discharged state, and the first two to three cycles on a slow base-station charger are conditioning cycles, not full-capacity cycles. The cells haven't yet formed their full electrochemical capacity. Run three complete charge-and-use cycles, placing the handset back in the base each time the low-battery tone sounds. By cycle four, measured capacity should align with the 1500mAh rating.

Base station charge light not coming on after battery swap

A NiMH pack that's been in storage can drop below the voltage threshold the base station expects before it begins trickle charging. The base reads the low voltage as an absent or faulty pack and withholds the charge current. Remove the handset, wait 30 seconds, and reseat it firmly — contact pressure matters on the KX-TG4500 charging pins. If the light still doesn't come on, check the terminal voltage with a multimeter; a pack sitting above 4.8V should trigger the charger normally.