Uniross CP75 Cordless Phone Compatible Battery 3.7V 500mAh

Uniross CP75 — 3.7V Li-Polymer Replacement Battery (CP75)

This is a 3.7V, 500mAh Li-Polymer replacement battery for the Uniross CP75 cordless phone handset. It fits directly into the handset battery compartment and restores power to the wireless telephone. Install this when the original cell no longer holds a charge or causes the handset to shut off during calls.

• CP75 handset fit: The CP75 battery slot accepts a specific cell footprint — 41.90 x 29.24 x 5.07mm. This replacement matches those dimensions exactly and uses the same connector orientation, so the handset BMS recognises the cell and allows normal charge cycles.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on a Li-Polymer test rig. The BMS accepted charge at the standard 4.2V cutoff and held voltage flat across light RF transmit loads typical of DECT handset use.
• First charge after installation: Li-Polymer cells in DECT handsets can sit in storage for months before sale. Place the handset in the base immediately after fitting and leave it for a full uninterrupted charge cycle before making calls — this lets the BMS calibrate its state-of-charge readings accurately.

Range dropping on the CP75 after a battery swap

DECT handsets ramp transmit power based on distance from the base station. When a fresh Li-Polymer cell has not completed its first full charge cycle, terminal voltage sags under the RF transmit load. The handset interprets that voltage drop as a weak signal and reduces output power, which cuts usable range. Run two or three full charge cycles and range returns to normal once the cell stabilises at rated capacity.

Handset loses pairing with base after battery removal

Some DECT phones store pairing data in volatile memory backed by the handset battery. Removing the old cell completely clears that memory, and the handset comes back up as unregistered. The fix is straightforward: press and hold the registration button on the base station, then initiate pairing from the handset menu. Consult the handset label for the default PIN — most Uniross units use 0000.