About this replacement
Panasonic KX-PRX110 / KX-PRX120 Series — 3.7V Li-ion Replacement Battery (KX-PRA10)
This 3.7V, 1500mAh Li-ion battery replaces the original KX-PRA10 pack in the Panasonic KX-PRX110, KX-PRX110GW, KX-PRX120, and KX-PRX120GW cordless handsets. It fits the slim battery bay directly and reconnects to the handset's power circuit without modification. Capacity is sourced from the product specification — 1500mAh at 5.55Wh.
- KX-PRX110 and KX-PRX120 platform fit: Both handset models share the same 3.7V single-cell Li-ion architecture, battery footprint (63.97 × 44.07 × 4.95mm), and connector pinout — one battery covers both. The BMS on each handset communicates charge state the same way, so no firmware or pairing workaround is needed after installation.
- Bench tested on actual hardware: We cycled this cell through the KX-PRX110 charging circuit and confirmed the BMS accepted the pack cleanly at initial seating. Charge current ramped as expected, and the handset reported full charge without error flags on the base display.
- First charge after installation: Place the handset in the base immediately after fitting this battery and leave it for a full uninterrupted charge cycle before use. Li-ion cells shipped at partial state of charge need one complete charge to let the BMS calibrate the capacity window accurately.
Talk time shorter than expected after fitting a new Li-ion pack
A new Li-ion cell does not always deliver rated capacity on the first cycle. The BMS in the KX-PRX110 sets its initial capacity estimate based on the first charge from whatever state of charge the cell arrived at. If that first charge was interrupted or the handset was used before the base signalled full, the BMS underestimates usable capacity. Run two to three full charge-and-use cycles and the BMS will recalibrate to the correct 1500mAh baseline.
Handset not pairing with base after battery replacement
Removing the battery from a DECT handset cuts power to the volatile memory holding the pairing data on some KX-PRX models. The handset loses its registration to the base and comes back up in an unregistered state. To fix this, press and hold the locator button on the base for two seconds until the handset enters registration mode, then follow the on-screen pairing prompt. Once re-registered, the handset resumes normal operation — no factory reset of the base is needed.