Estry KX-TC1721 3.6V 700mAh standard battery

Replacement battery for Panasonic cordless phones

The Estry KX-TC1721 is a 3.6 V, 700 mAh nickel-metal-hydride pack built to match the original specifications for Panasonic handsets including the KX-TC1721, KX-FPC91, KX-TG2583, KX-TC1750, KX-TC1858, KX-TC1852 and KX-T3845 series. It also replaces part numbers P-P508, KX-A36, P-P501, P-P510, TYPE 21, HHR-P505PA, RCT-3A-C1, HHR-P505, TYPE 1, P-P504 and KX-TCA14. The cell carries ISO 9001, RoHS, CE, UN 38.3 and MSDS certifications.

Drop-in fit with no soldering required

The pack measures 50.79 x 42.4 x 14.23 mm and weighs 114.3 g, matching the factory footprint so it slides into the handset battery compartment without modification. No wiring changes or external chargers are needed; the handset’s own cradle handles charging once the replacement is installed. Buyers whose handset uses a different voltage, capacity or physical layout will need a different pack.

Steady output through repeated charge cycles

Rated at 2.52 Wh, the Ni-MH chemistry delivers a stable 3.6 V nominal voltage across the discharge curve, avoiding the sharp voltage drop that can cause handsets to cut out early. Built-in protection guards against over-charge, over-discharge, over-voltage and short-circuit events, helping the pack maintain usable capacity over a full year of daily charge-and-discharge cycles.